/usr/lib/python3/dist-packages/sqlalchemy/dialects/sqlite/base.py is in python3-sqlalchemy 1.0.15+ds1-1.
This file is owned by root:root, with mode 0o644.
The actual contents of the file can be viewed below.
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 184 185 186 187 188 189 190 191 192 193 194 195 196 197 198 199 200 201 202 203 204 205 206 207 208 209 210 211 212 213 214 215 216 217 218 219 220 221 222 223 224 225 226 227 228 229 230 231 232 233 234 235 236 237 238 239 240 241 242 243 244 245 246 247 248 249 250 251 252 253 254 255 256 257 258 259 260 261 262 263 264 265 266 267 268 269 270 271 272 273 274 275 276 277 278 279 280 281 282 283 284 285 286 287 288 289 290 291 292 293 294 295 296 297 298 299 300 301 302 303 304 305 306 307 308 309 310 311 312 313 314 315 316 317 318 319 320 321 322 323 324 325 326 327 328 329 330 331 332 333 334 335 336 337 338 339 340 341 342 343 344 345 346 347 348 349 350 351 352 353 354 355 356 357 358 359 360 361 362 363 364 365 366 367 368 369 370 371 372 373 374 375 376 377 378 379 380 381 382 383 384 385 386 387 388 389 390 391 392 393 394 395 396 397 398 399 400 401 402 403 404 405 406 407 408 409 410 411 412 413 414 415 416 417 418 419 420 421 422 423 424 425 426 427 428 429 430 431 432 433 434 435 436 437 438 439 440 441 442 443 444 445 446 447 448 449 450 451 452 453 454 455 456 457 458 459 460 461 462 463 464 465 466 467 468 469 470 471 472 473 474 475 476 477 478 479 480 481 482 483 484 485 486 487 488 489 490 491 492 493 494 495 496 497 498 499 500 501 502 503 504 505 506 507 508 509 510 511 512 513 514 515 516 517 518 519 520 521 522 523 524 525 526 527 528 529 530 531 532 533 534 535 536 537 538 539 540 541 542 543 544 545 546 547 548 549 550 551 552 553 554 555 556 557 558 559 560 561 562 563 564 565 566 567 568 569 570 571 572 573 574 575 576 577 578 579 580 581 582 583 584 585 586 587 588 589 590 591 592 593 594 595 596 597 598 599 600 601 602 603 604 605 606 607 608 609 610 611 612 613 614 615 616 617 618 619 620 621 622 623 624 625 626 627 628 629 630 631 632 633 634 635 636 637 638 639 640 641 642 643 644 645 646 647 648 649 650 651 652 653 654 655 656 657 658 659 660 661 662 663 664 665 666 667 668 669 670 671 672 673 674 675 676 677 678 679 680 681 682 683 684 685 686 687 688 689 690 691 692 693 694 695 696 697 698 699 700 701 702 703 704 705 706 707 708 709 710 711 712 713 714 715 716 717 718 719 720 721 722 723 724 725 726 727 728 729 730 731 732 733 734 735 736 737 738 739 740 741 742 743 744 745 746 747 748 749 750 751 752 753 754 755 756 757 758 759 760 761 762 763 764 765 766 767 768 769 770 771 772 773 774 775 776 777 778 779 780 781 782 783 784 785 786 787 788 789 790 791 792 793 794 795 796 797 798 799 800 801 802 803 804 805 806 807 808 809 810 811 812 813 814 815 816 817 818 819 820 821 822 823 824 825 826 827 828 829 830 831 832 833 834 835 836 837 838 839 840 841 842 843 844 845 846 847 848 849 850 851 852 853 854 855 856 857 858 859 860 861 862 863 864 865 866 867 868 869 870 871 872 873 874 875 876 877 878 879 880 881 882 883 884 885 886 887 888 889 890 891 892 893 894 895 896 897 898 899 900 901 902 903 904 905 906 907 908 909 910 911 912 913 914 915 916 917 918 919 920 921 922 923 924 925 926 927 928 929 930 931 932 933 934 935 936 937 938 939 940 941 942 943 944 945 946 947 948 949 950 951 952 953 954 955 956 957 958 959 960 961 962 963 964 965 966 967 968 969 970 971 972 973 974 975 976 977 978 979 980 981 982 983 984 985 986 987 988 989 990 991 992 993 994 995 996 997 998 999 1000 1001 1002 1003 1004 1005 1006 1007 1008 1009 1010 1011 1012 1013 1014 1015 1016 1017 1018 1019 1020 1021 1022 1023 1024 1025 1026 1027 1028 1029 1030 1031 1032 1033 1034 1035 1036 1037 1038 1039 1040 1041 1042 1043 1044 1045 1046 1047 1048 1049 1050 1051 1052 1053 1054 1055 1056 1057 1058 1059 1060 1061 1062 1063 1064 1065 1066 1067 1068 1069 1070 1071 1072 1073 1074 1075 1076 1077 1078 1079 1080 1081 1082 1083 1084 1085 1086 1087 1088 1089 1090 1091 1092 1093 1094 1095 1096 1097 1098 1099 1100 1101 1102 1103 1104 1105 1106 1107 1108 1109 1110 1111 1112 1113 1114 1115 1116 1117 1118 1119 1120 1121 1122 1123 1124 1125 1126 1127 1128 1129 1130 1131 1132 1133 1134 1135 1136 1137 1138 1139 1140 1141 1142 1143 1144 1145 1146 1147 1148 1149 1150 1151 1152 1153 1154 1155 1156 1157 1158 1159 1160 1161 1162 1163 1164 1165 1166 1167 1168 1169 1170 1171 1172 1173 1174 1175 1176 1177 1178 1179 1180 1181 1182 1183 1184 1185 1186 1187 1188 1189 1190 1191 1192 1193 1194 1195 1196 1197 1198 1199 1200 1201 1202 1203 1204 1205 1206 1207 1208 1209 1210 1211 1212 1213 1214 1215 1216 1217 1218 1219 1220 1221 1222 1223 1224 1225 1226 1227 1228 1229 1230 1231 1232 1233 1234 1235 1236 1237 1238 1239 1240 1241 1242 1243 1244 1245 1246 1247 1248 1249 1250 1251 1252 1253 1254 1255 1256 1257 1258 1259 1260 1261 1262 1263 1264 1265 1266 1267 1268 1269 1270 1271 1272 1273 1274 1275 1276 1277 1278 1279 1280 1281 1282 1283 1284 1285 1286 1287 1288 1289 1290 1291 1292 1293 1294 1295 1296 1297 1298 1299 1300 1301 1302 1303 1304 1305 1306 1307 1308 1309 1310 1311 1312 1313 1314 1315 1316 1317 1318 1319 1320 1321 1322 1323 1324 1325 1326 1327 1328 1329 1330 1331 1332 1333 1334 1335 1336 1337 1338 1339 1340 1341 1342 1343 1344 1345 1346 1347 1348 1349 1350 1351 1352 1353 1354 1355 1356 1357 1358 1359 1360 1361 1362 1363 1364 1365 1366 1367 1368 1369 1370 1371 1372 1373 1374 1375 1376 1377 1378 1379 1380 1381 1382 1383 1384 1385 1386 1387 1388 1389 1390 1391 1392 1393 1394 1395 1396 1397 1398 1399 1400 1401 1402 1403 1404 1405 1406 1407 1408 1409 1410 1411 1412 1413 1414 1415 1416 1417 1418 1419 1420 1421 1422 1423 1424 1425 1426 1427 1428 1429 1430 1431 1432 1433 1434 1435 1436 1437 1438 1439 1440 1441 1442 1443 1444 1445 1446 1447 1448 1449 1450 1451 1452 1453 1454 1455 1456 1457 1458 1459 1460 1461 1462 1463 1464 1465 1466 1467 1468 1469 1470 1471 1472 1473 1474 1475 1476 1477 1478 1479 1480 1481 1482 1483 1484 1485 1486 1487 1488 | # sqlite/base.py
# Copyright (C) 2005-2016 the SQLAlchemy authors and contributors
# <see AUTHORS file>
#
# This module is part of SQLAlchemy and is released under
# the MIT License: http://www.opensource.org/licenses/mit-license.php
"""
.. dialect:: sqlite
:name: SQLite
.. _sqlite_datetime:
Date and Time Types
-------------------
SQLite does not have built-in DATE, TIME, or DATETIME types, and pysqlite does
not provide out of the box functionality for translating values between Python
`datetime` objects and a SQLite-supported format. SQLAlchemy's own
:class:`~sqlalchemy.types.DateTime` and related types provide date formatting
and parsing functionality when SQlite is used. The implementation classes are
:class:`~.sqlite.DATETIME`, :class:`~.sqlite.DATE` and :class:`~.sqlite.TIME`.
These types represent dates and times as ISO formatted strings, which also
nicely support ordering. There's no reliance on typical "libc" internals for
these functions so historical dates are fully supported.
Ensuring Text affinity
^^^^^^^^^^^^^^^^^^^^^^
The DDL rendered for these types is the standard ``DATE``, ``TIME``
and ``DATETIME`` indicators. However, custom storage formats can also be
applied to these types. When the
storage format is detected as containing no alpha characters, the DDL for
these types is rendered as ``DATE_CHAR``, ``TIME_CHAR``, and ``DATETIME_CHAR``,
so that the column continues to have textual affinity.
.. seealso::
`Type Affinity <http://www.sqlite.org/datatype3.html#affinity>`_ - in the SQLite documentation
.. _sqlite_autoincrement:
SQLite Auto Incrementing Behavior
----------------------------------
Background on SQLite's autoincrement is at: http://sqlite.org/autoinc.html
Key concepts:
* SQLite has an implicit "auto increment" feature that takes place for any
non-composite primary-key column that is specifically created using
"INTEGER PRIMARY KEY" for the type + primary key.
* SQLite also has an explicit "AUTOINCREMENT" keyword, that is **not**
equivalent to the implicit autoincrement feature; this keyword is not
recommended for general use. SQLAlchemy does not render this keyword
unless a special SQLite-specific directive is used (see below). However,
it still requires that the column's type is named "INTEGER".
Using the AUTOINCREMENT Keyword
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
To specifically render the AUTOINCREMENT keyword on the primary key column
when rendering DDL, add the flag ``sqlite_autoincrement=True`` to the Table
construct::
Table('sometable', metadata,
Column('id', Integer, primary_key=True),
sqlite_autoincrement=True)
Allowing autoincrement behavior SQLAlchemy types other than Integer/INTEGER
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
SQLite's typing model is based on naming conventions. Among
other things, this means that any type name which contains the
substring ``"INT"`` will be determined to be of "integer affinity". A
type named ``"BIGINT"``, ``"SPECIAL_INT"`` or even ``"XYZINTQPR"``, will be considered by
SQLite to be of "integer" affinity. However, **the SQLite
autoincrement feature, whether implicitly or explicitly enabled,
requires that the name of the column's type
is exactly the string "INTEGER"**. Therefore, if an
application uses a type like :class:`.BigInteger` for a primary key, on
SQLite this type will need to be rendered as the name ``"INTEGER"`` when
emitting the initial ``CREATE TABLE`` statement in order for the autoincrement
behavior to be available.
One approach to achieve this is to use :class:`.Integer` on SQLite
only using :meth:`.TypeEngine.with_variant`::
table = Table(
"my_table", metadata,
Column("id", BigInteger().with_variant(Integer, "sqlite"), primary_key=True)
)
Another is to use a subclass of :class:`.BigInteger` that overrides its DDL name
to be ``INTEGER`` when compiled against SQLite::
from sqlalchemy import BigInteger
from sqlalchemy.ext.compiler import compiles
class SLBigInteger(BigInteger):
pass
@compiles(SLBigInteger, 'sqlite')
def bi_c(element, compiler, **kw):
return "INTEGER"
@compiles(SLBigInteger)
def bi_c(element, compiler, **kw):
return compiler.visit_BIGINT(element, **kw)
table = Table(
"my_table", metadata,
Column("id", SLBigInteger(), primary_key=True)
)
.. seealso::
:meth:`.TypeEngine.with_variant`
:ref:`sqlalchemy.ext.compiler_toplevel`
`Datatypes In SQLite Version 3 <http://sqlite.org/datatype3.html>`_
.. _sqlite_concurrency:
Database Locking Behavior / Concurrency
---------------------------------------
SQLite is not designed for a high level of write concurrency. The database
itself, being a file, is locked completely during write operations within
transactions, meaning exactly one "connection" (in reality a file handle)
has exclusive access to the database during this period - all other
"connections" will be blocked during this time.
The Python DBAPI specification also calls for a connection model that is
always in a transaction; there is no ``connection.begin()`` method,
only ``connection.commit()`` and ``connection.rollback()``, upon which a
new transaction is to be begun immediately. This may seem to imply
that the SQLite driver would in theory allow only a single filehandle on a
particular database file at any time; however, there are several
factors both within SQlite itself as well as within the pysqlite driver
which loosen this restriction significantly.
However, no matter what locking modes are used, SQLite will still always
lock the database file once a transaction is started and DML (e.g. INSERT,
UPDATE, DELETE) has at least been emitted, and this will block
other transactions at least at the point that they also attempt to emit DML.
By default, the length of time on this block is very short before it times out
with an error.
This behavior becomes more critical when used in conjunction with the
SQLAlchemy ORM. SQLAlchemy's :class:`.Session` object by default runs
within a transaction, and with its autoflush model, may emit DML preceding
any SELECT statement. This may lead to a SQLite database that locks
more quickly than is expected. The locking mode of SQLite and the pysqlite
driver can be manipulated to some degree, however it should be noted that
achieving a high degree of write-concurrency with SQLite is a losing battle.
For more information on SQLite's lack of write concurrency by design, please
see
`Situations Where Another RDBMS May Work Better - High Concurrency
<http://www.sqlite.org/whentouse.html>`_ near the bottom of the page.
The following subsections introduce areas that are impacted by SQLite's
file-based architecture and additionally will usually require workarounds to
work when using the pysqlite driver.
.. _sqlite_isolation_level:
Transaction Isolation Level
----------------------------
SQLite supports "transaction isolation" in a non-standard way, along two
axes. One is that of the `PRAGMA read_uncommitted <http://www.sqlite.org/pragma.html#pragma_read_uncommitted>`_
instruction. This setting can essentially switch SQLite between its
default mode of ``SERIALIZABLE`` isolation, and a "dirty read" isolation
mode normally referred to as ``READ UNCOMMITTED``.
SQLAlchemy ties into this PRAGMA statement using the
:paramref:`.create_engine.isolation_level` parameter of :func:`.create_engine`.
Valid values for this parameter when used with SQLite are ``"SERIALIZABLE"``
and ``"READ UNCOMMITTED"`` corresponding to a value of 0 and 1, respectively.
SQLite defaults to ``SERIALIZABLE``, however its behavior is impacted by
the pysqlite driver's default behavior.
The other axis along which SQLite's transactional locking is impacted is
via the nature of the ``BEGIN`` statement used. The three varieties
are "deferred", "immediate", and "exclusive", as described at
`BEGIN TRANSACTION <http://sqlite.org/lang_transaction.html>`_. A straight
``BEGIN`` statement uses the "deferred" mode, where the the database file is
not locked until the first read or write operation, and read access remains
open to other transactions until the first write operation. But again,
it is critical to note that the pysqlite driver interferes with this behavior
by *not even emitting BEGIN* until the first write operation.
.. warning::
SQLite's transactional scope is impacted by unresolved
issues in the pysqlite driver, which defers BEGIN statements to a greater
degree than is often feasible. See the section :ref:`pysqlite_serializable`
for techniques to work around this behavior.
SAVEPOINT Support
----------------------------
SQLite supports SAVEPOINTs, which only function once a transaction is
begun. SQLAlchemy's SAVEPOINT support is available using the
:meth:`.Connection.begin_nested` method at the Core level, and
:meth:`.Session.begin_nested` at the ORM level. However, SAVEPOINTs
won't work at all with pysqlite unless workarounds are taken.
.. warning::
SQLite's SAVEPOINT feature is impacted by unresolved
issues in the pysqlite driver, which defers BEGIN statements to a greater
degree than is often feasible. See the section :ref:`pysqlite_serializable`
for techniques to work around this behavior.
Transactional DDL
----------------------------
The SQLite database supports transactional :term:`DDL` as well.
In this case, the pysqlite driver is not only failing to start transactions,
it also is ending any existing transction when DDL is detected, so again,
workarounds are required.
.. warning::
SQLite's transactional DDL is impacted by unresolved issues
in the pysqlite driver, which fails to emit BEGIN and additionally
forces a COMMIT to cancel any transaction when DDL is encountered.
See the section :ref:`pysqlite_serializable`
for techniques to work around this behavior.
.. _sqlite_foreign_keys:
Foreign Key Support
-------------------
SQLite supports FOREIGN KEY syntax when emitting CREATE statements for tables,
however by default these constraints have no effect on the operation of the
table.
Constraint checking on SQLite has three prerequisites:
* At least version 3.6.19 of SQLite must be in use
* The SQLite library must be compiled *without* the SQLITE_OMIT_FOREIGN_KEY
or SQLITE_OMIT_TRIGGER symbols enabled.
* The ``PRAGMA foreign_keys = ON`` statement must be emitted on all
connections before use.
SQLAlchemy allows for the ``PRAGMA`` statement to be emitted automatically for
new connections through the usage of events::
from sqlalchemy.engine import Engine
from sqlalchemy import event
@event.listens_for(Engine, "connect")
def set_sqlite_pragma(dbapi_connection, connection_record):
cursor = dbapi_connection.cursor()
cursor.execute("PRAGMA foreign_keys=ON")
cursor.close()
.. warning::
When SQLite foreign keys are enabled, it is **not possible**
to emit CREATE or DROP statements for tables that contain
mutually-dependent foreign key constraints;
to emit the DDL for these tables requires that ALTER TABLE be used to
create or drop these constraints separately, for which SQLite has
no support.
.. seealso::
`SQLite Foreign Key Support <http://www.sqlite.org/foreignkeys.html>`_
- on the SQLite web site.
:ref:`event_toplevel` - SQLAlchemy event API.
:ref:`use_alter` - more information on SQLAlchemy's facilities for handling
mutually-dependent foreign key constraints.
.. _sqlite_type_reflection:
Type Reflection
---------------
SQLite types are unlike those of most other database backends, in that
the string name of the type usually does not correspond to a "type" in a
one-to-one fashion. Instead, SQLite links per-column typing behavior
to one of five so-called "type affinities" based on a string matching
pattern for the type.
SQLAlchemy's reflection process, when inspecting types, uses a simple
lookup table to link the keywords returned to provided SQLAlchemy types.
This lookup table is present within the SQLite dialect as it is for all
other dialects. However, the SQLite dialect has a different "fallback"
routine for when a particular type name is not located in the lookup map;
it instead implements the SQLite "type affinity" scheme located at
http://www.sqlite.org/datatype3.html section 2.1.
The provided typemap will make direct associations from an exact string
name match for the following types:
:class:`~.types.BIGINT`, :class:`~.types.BLOB`,
:class:`~.types.BOOLEAN`, :class:`~.types.BOOLEAN`,
:class:`~.types.CHAR`, :class:`~.types.DATE`,
:class:`~.types.DATETIME`, :class:`~.types.FLOAT`,
:class:`~.types.DECIMAL`, :class:`~.types.FLOAT`,
:class:`~.types.INTEGER`, :class:`~.types.INTEGER`,
:class:`~.types.NUMERIC`, :class:`~.types.REAL`,
:class:`~.types.SMALLINT`, :class:`~.types.TEXT`,
:class:`~.types.TIME`, :class:`~.types.TIMESTAMP`,
:class:`~.types.VARCHAR`, :class:`~.types.NVARCHAR`,
:class:`~.types.NCHAR`
When a type name does not match one of the above types, the "type affinity"
lookup is used instead:
* :class:`~.types.INTEGER` is returned if the type name includes the
string ``INT``
* :class:`~.types.TEXT` is returned if the type name includes the
string ``CHAR``, ``CLOB`` or ``TEXT``
* :class:`~.types.NullType` is returned if the type name includes the
string ``BLOB``
* :class:`~.types.REAL` is returned if the type name includes the string
``REAL``, ``FLOA`` or ``DOUB``.
* Otherwise, the :class:`~.types.NUMERIC` type is used.
.. versionadded:: 0.9.3 Support for SQLite type affinity rules when reflecting
columns.
.. _sqlite_partial_index:
Partial Indexes
---------------
A partial index, e.g. one which uses a WHERE clause, can be specified
with the DDL system using the argument ``sqlite_where``::
tbl = Table('testtbl', m, Column('data', Integer))
idx = Index('test_idx1', tbl.c.data,
sqlite_where=and_(tbl.c.data > 5, tbl.c.data < 10))
The index will be rendered at create time as::
CREATE INDEX test_idx1 ON testtbl (data)
WHERE data > 5 AND data < 10
.. versionadded:: 0.9.9
Dotted Column Names
-------------------
Using table or column names that explicitly have periods in them is
**not recommended**. While this is generally a bad idea for relational
databases in general, as the dot is a syntactically significant character,
the SQLite driver up until version **3.10.0** of SQLite has a bug which
requires that SQLAlchemy filter out these dots in result sets.
.. note::
The following SQLite issue has been resolved as of version 3.10.0
of SQLite. SQLAlchemy as of **1.1** automatically disables its internal
workarounds based on detection of this version.
The bug, entirely outside of SQLAlchemy, can be illustrated thusly::
import sqlite3
conn = sqlite3.connect(":memory:")
cursor = conn.cursor()
cursor.execute("create table x (a integer, b integer)")
cursor.execute("insert into x (a, b) values (1, 1)")
cursor.execute("insert into x (a, b) values (2, 2)")
cursor.execute("select x.a, x.b from x")
assert [c[0] for c in cursor.description] == ['a', 'b']
cursor.execute('''
select x.a, x.b from x where a=1
union
select x.a, x.b from x where a=2
''')
assert [c[0] for c in cursor.description] == ['a', 'b'], \\
[c[0] for c in cursor.description]
The second assertion fails::
Traceback (most recent call last):
File "test.py", line 19, in <module>
[c[0] for c in cursor.description]
AssertionError: ['x.a', 'x.b']
Where above, the driver incorrectly reports the names of the columns
including the name of the table, which is entirely inconsistent vs.
when the UNION is not present.
SQLAlchemy relies upon column names being predictable in how they match
to the original statement, so the SQLAlchemy dialect has no choice but
to filter these out::
from sqlalchemy import create_engine
eng = create_engine("sqlite://")
conn = eng.connect()
conn.execute("create table x (a integer, b integer)")
conn.execute("insert into x (a, b) values (1, 1)")
conn.execute("insert into x (a, b) values (2, 2)")
result = conn.execute("select x.a, x.b from x")
assert result.keys() == ["a", "b"]
result = conn.execute('''
select x.a, x.b from x where a=1
union
select x.a, x.b from x where a=2
''')
assert result.keys() == ["a", "b"]
Note that above, even though SQLAlchemy filters out the dots, *both
names are still addressable*::
>>> row = result.first()
>>> row["a"]
1
>>> row["x.a"]
1
>>> row["b"]
1
>>> row["x.b"]
1
Therefore, the workaround applied by SQLAlchemy only impacts
:meth:`.ResultProxy.keys` and :meth:`.RowProxy.keys()` in the public API.
In the very specific case where
an application is forced to use column names that contain dots, and the
functionality of :meth:`.ResultProxy.keys` and :meth:`.RowProxy.keys()`
is required to return these dotted names unmodified, the ``sqlite_raw_colnames``
execution option may be provided, either on a per-:class:`.Connection` basis::
result = conn.execution_options(sqlite_raw_colnames=True).execute('''
select x.a, x.b from x where a=1
union
select x.a, x.b from x where a=2
''')
assert result.keys() == ["x.a", "x.b"]
or on a per-:class:`.Engine` basis::
engine = create_engine("sqlite://", execution_options={"sqlite_raw_colnames": True})
When using the per-:class:`.Engine` execution option, note that
**Core and ORM queries that use UNION may not function properly**.
"""
import datetime
import re
from ... import processors
from ... import sql, exc
from ... import types as sqltypes, schema as sa_schema
from ... import util
from ...engine import default, reflection
from ...sql import compiler
from ...types import (BLOB, BOOLEAN, CHAR, DECIMAL, FLOAT,
INTEGER, REAL, NUMERIC, SMALLINT, TEXT,
TIMESTAMP, VARCHAR)
class _DateTimeMixin(object):
_reg = None
_storage_format = None
def __init__(self, storage_format=None, regexp=None, **kw):
super(_DateTimeMixin, self).__init__(**kw)
if regexp is not None:
self._reg = re.compile(regexp)
if storage_format is not None:
self._storage_format = storage_format
@property
def format_is_text_affinity(self):
"""return True if the storage format will automatically imply
a TEXT affinity.
If the storage format contains no non-numeric characters,
it will imply a NUMERIC storage format on SQLite; in this case,
the type will generate its DDL as DATE_CHAR, DATETIME_CHAR,
TIME_CHAR.
.. versionadded:: 1.0.0
"""
spec = self._storage_format % {
"year": 0, "month": 0, "day": 0, "hour": 0,
"minute": 0, "second": 0, "microsecond": 0
}
return bool(re.search(r'[^0-9]', spec))
def adapt(self, cls, **kw):
if issubclass(cls, _DateTimeMixin):
if self._storage_format:
kw["storage_format"] = self._storage_format
if self._reg:
kw["regexp"] = self._reg
return super(_DateTimeMixin, self).adapt(cls, **kw)
def literal_processor(self, dialect):
bp = self.bind_processor(dialect)
def process(value):
return "'%s'" % bp(value)
return process
class DATETIME(_DateTimeMixin, sqltypes.DateTime):
"""Represent a Python datetime object in SQLite using a string.
The default string storage format is::
"%(year)04d-%(month)02d-%(day)02d %(hour)02d:%(min)02d:\
%(second)02d.%(microsecond)06d"
e.g.::
2011-03-15 12:05:57.10558
The storage format can be customized to some degree using the
``storage_format`` and ``regexp`` parameters, such as::
import re
from sqlalchemy.dialects.sqlite import DATETIME
dt = DATETIME(
storage_format="%(year)04d/%(month)02d/%(day)02d %(hour)02d:\
%(min)02d:%(second)02d",
regexp=r"(\d+)/(\d+)/(\d+) (\d+)-(\d+)-(\d+)"
)
:param storage_format: format string which will be applied to the dict
with keys year, month, day, hour, minute, second, and microsecond.
:param regexp: regular expression which will be applied to incoming result
rows. If the regexp contains named groups, the resulting match dict is
applied to the Python datetime() constructor as keyword arguments.
Otherwise, if positional groups are used, the datetime() constructor
is called with positional arguments via
``*map(int, match_obj.groups(0))``.
"""
_storage_format = (
"%(year)04d-%(month)02d-%(day)02d "
"%(hour)02d:%(minute)02d:%(second)02d.%(microsecond)06d"
)
def __init__(self, *args, **kwargs):
truncate_microseconds = kwargs.pop('truncate_microseconds', False)
super(DATETIME, self).__init__(*args, **kwargs)
if truncate_microseconds:
assert 'storage_format' not in kwargs, "You can specify only "\
"one of truncate_microseconds or storage_format."
assert 'regexp' not in kwargs, "You can specify only one of "\
"truncate_microseconds or regexp."
self._storage_format = (
"%(year)04d-%(month)02d-%(day)02d "
"%(hour)02d:%(minute)02d:%(second)02d"
)
def bind_processor(self, dialect):
datetime_datetime = datetime.datetime
datetime_date = datetime.date
format = self._storage_format
def process(value):
if value is None:
return None
elif isinstance(value, datetime_datetime):
return format % {
'year': value.year,
'month': value.month,
'day': value.day,
'hour': value.hour,
'minute': value.minute,
'second': value.second,
'microsecond': value.microsecond,
}
elif isinstance(value, datetime_date):
return format % {
'year': value.year,
'month': value.month,
'day': value.day,
'hour': 0,
'minute': 0,
'second': 0,
'microsecond': 0,
}
else:
raise TypeError("SQLite DateTime type only accepts Python "
"datetime and date objects as input.")
return process
def result_processor(self, dialect, coltype):
if self._reg:
return processors.str_to_datetime_processor_factory(
self._reg, datetime.datetime)
else:
return processors.str_to_datetime
class DATE(_DateTimeMixin, sqltypes.Date):
"""Represent a Python date object in SQLite using a string.
The default string storage format is::
"%(year)04d-%(month)02d-%(day)02d"
e.g.::
2011-03-15
The storage format can be customized to some degree using the
``storage_format`` and ``regexp`` parameters, such as::
import re
from sqlalchemy.dialects.sqlite import DATE
d = DATE(
storage_format="%(month)02d/%(day)02d/%(year)04d",
regexp=re.compile("(?P<month>\d+)/(?P<day>\d+)/(?P<year>\d+)")
)
:param storage_format: format string which will be applied to the
dict with keys year, month, and day.
:param regexp: regular expression which will be applied to
incoming result rows. If the regexp contains named groups, the
resulting match dict is applied to the Python date() constructor
as keyword arguments. Otherwise, if positional groups are used, the
date() constructor is called with positional arguments via
``*map(int, match_obj.groups(0))``.
"""
_storage_format = "%(year)04d-%(month)02d-%(day)02d"
def bind_processor(self, dialect):
datetime_date = datetime.date
format = self._storage_format
def process(value):
if value is None:
return None
elif isinstance(value, datetime_date):
return format % {
'year': value.year,
'month': value.month,
'day': value.day,
}
else:
raise TypeError("SQLite Date type only accepts Python "
"date objects as input.")
return process
def result_processor(self, dialect, coltype):
if self._reg:
return processors.str_to_datetime_processor_factory(
self._reg, datetime.date)
else:
return processors.str_to_date
class TIME(_DateTimeMixin, sqltypes.Time):
"""Represent a Python time object in SQLite using a string.
The default string storage format is::
"%(hour)02d:%(minute)02d:%(second)02d.%(microsecond)06d"
e.g.::
12:05:57.10558
The storage format can be customized to some degree using the
``storage_format`` and ``regexp`` parameters, such as::
import re
from sqlalchemy.dialects.sqlite import TIME
t = TIME(
storage_format="%(hour)02d-%(minute)02d-%(second)02d-\
%(microsecond)06d",
regexp=re.compile("(\d+)-(\d+)-(\d+)-(?:-(\d+))?")
)
:param storage_format: format string which will be applied to the dict
with keys hour, minute, second, and microsecond.
:param regexp: regular expression which will be applied to incoming result
rows. If the regexp contains named groups, the resulting match dict is
applied to the Python time() constructor as keyword arguments. Otherwise,
if positional groups are used, the time() constructor is called with
positional arguments via ``*map(int, match_obj.groups(0))``.
"""
_storage_format = "%(hour)02d:%(minute)02d:%(second)02d.%(microsecond)06d"
def __init__(self, *args, **kwargs):
truncate_microseconds = kwargs.pop('truncate_microseconds', False)
super(TIME, self).__init__(*args, **kwargs)
if truncate_microseconds:
assert 'storage_format' not in kwargs, "You can specify only "\
"one of truncate_microseconds or storage_format."
assert 'regexp' not in kwargs, "You can specify only one of "\
"truncate_microseconds or regexp."
self._storage_format = "%(hour)02d:%(minute)02d:%(second)02d"
def bind_processor(self, dialect):
datetime_time = datetime.time
format = self._storage_format
def process(value):
if value is None:
return None
elif isinstance(value, datetime_time):
return format % {
'hour': value.hour,
'minute': value.minute,
'second': value.second,
'microsecond': value.microsecond,
}
else:
raise TypeError("SQLite Time type only accepts Python "
"time objects as input.")
return process
def result_processor(self, dialect, coltype):
if self._reg:
return processors.str_to_datetime_processor_factory(
self._reg, datetime.time)
else:
return processors.str_to_time
colspecs = {
sqltypes.Date: DATE,
sqltypes.DateTime: DATETIME,
sqltypes.Time: TIME,
}
ischema_names = {
'BIGINT': sqltypes.BIGINT,
'BLOB': sqltypes.BLOB,
'BOOL': sqltypes.BOOLEAN,
'BOOLEAN': sqltypes.BOOLEAN,
'CHAR': sqltypes.CHAR,
'DATE': sqltypes.DATE,
'DATE_CHAR': sqltypes.DATE,
'DATETIME': sqltypes.DATETIME,
'DATETIME_CHAR': sqltypes.DATETIME,
'DOUBLE': sqltypes.FLOAT,
'DECIMAL': sqltypes.DECIMAL,
'FLOAT': sqltypes.FLOAT,
'INT': sqltypes.INTEGER,
'INTEGER': sqltypes.INTEGER,
'NUMERIC': sqltypes.NUMERIC,
'REAL': sqltypes.REAL,
'SMALLINT': sqltypes.SMALLINT,
'TEXT': sqltypes.TEXT,
'TIME': sqltypes.TIME,
'TIME_CHAR': sqltypes.TIME,
'TIMESTAMP': sqltypes.TIMESTAMP,
'VARCHAR': sqltypes.VARCHAR,
'NVARCHAR': sqltypes.NVARCHAR,
'NCHAR': sqltypes.NCHAR,
}
class SQLiteCompiler(compiler.SQLCompiler):
extract_map = util.update_copy(
compiler.SQLCompiler.extract_map,
{
'month': '%m',
'day': '%d',
'year': '%Y',
'second': '%S',
'hour': '%H',
'doy': '%j',
'minute': '%M',
'epoch': '%s',
'dow': '%w',
'week': '%W',
})
def visit_now_func(self, fn, **kw):
return "CURRENT_TIMESTAMP"
def visit_localtimestamp_func(self, func, **kw):
return 'DATETIME(CURRENT_TIMESTAMP, "localtime")'
def visit_true(self, expr, **kw):
return '1'
def visit_false(self, expr, **kw):
return '0'
def visit_char_length_func(self, fn, **kw):
return "length%s" % self.function_argspec(fn)
def visit_cast(self, cast, **kwargs):
if self.dialect.supports_cast:
return super(SQLiteCompiler, self).visit_cast(cast, **kwargs)
else:
return self.process(cast.clause, **kwargs)
def visit_extract(self, extract, **kw):
try:
return "CAST(STRFTIME('%s', %s) AS INTEGER)" % (
self.extract_map[extract.field],
self.process(extract.expr, **kw)
)
except KeyError:
raise exc.CompileError(
"%s is not a valid extract argument." % extract.field)
def limit_clause(self, select, **kw):
text = ""
if select._limit_clause is not None:
text += "\n LIMIT " + self.process(select._limit_clause, **kw)
if select._offset_clause is not None:
if select._limit_clause is None:
text += "\n LIMIT " + self.process(sql.literal(-1))
text += " OFFSET " + self.process(select._offset_clause, **kw)
else:
text += " OFFSET " + self.process(sql.literal(0), **kw)
return text
def for_update_clause(self, select, **kw):
# sqlite has no "FOR UPDATE" AFAICT
return ''
class SQLiteDDLCompiler(compiler.DDLCompiler):
def get_column_specification(self, column, **kwargs):
coltype = self.dialect.type_compiler.process(
column.type, type_expression=column)
colspec = self.preparer.format_column(column) + " " + coltype
default = self.get_column_default_string(column)
if default is not None:
colspec += " DEFAULT " + default
if not column.nullable:
colspec += " NOT NULL"
if (column.primary_key and
column.table.dialect_options['sqlite']['autoincrement'] and
len(column.table.primary_key.columns) == 1 and
issubclass(column.type._type_affinity, sqltypes.Integer) and
not column.foreign_keys):
colspec += " PRIMARY KEY AUTOINCREMENT"
return colspec
def visit_primary_key_constraint(self, constraint):
# for columns with sqlite_autoincrement=True,
# the PRIMARY KEY constraint can only be inline
# with the column itself.
if len(constraint.columns) == 1:
c = list(constraint)[0]
if (c.primary_key and
c.table.dialect_options['sqlite']['autoincrement'] and
issubclass(c.type._type_affinity, sqltypes.Integer) and
not c.foreign_keys):
return None
return super(SQLiteDDLCompiler, self).visit_primary_key_constraint(
constraint)
def visit_foreign_key_constraint(self, constraint):
local_table = constraint.elements[0].parent.table
remote_table = constraint.elements[0].column.table
if local_table.schema != remote_table.schema:
return None
else:
return super(
SQLiteDDLCompiler,
self).visit_foreign_key_constraint(constraint)
def define_constraint_remote_table(self, constraint, table, preparer):
"""Format the remote table clause of a CREATE CONSTRAINT clause."""
return preparer.format_table(table, use_schema=False)
def visit_create_index(self, create):
index = create.element
text = super(SQLiteDDLCompiler, self).visit_create_index(
create, include_table_schema=False)
whereclause = index.dialect_options["sqlite"]["where"]
if whereclause is not None:
where_compiled = self.sql_compiler.process(
whereclause, include_table=False,
literal_binds=True)
text += " WHERE " + where_compiled
return text
class SQLiteTypeCompiler(compiler.GenericTypeCompiler):
def visit_large_binary(self, type_, **kw):
return self.visit_BLOB(type_)
def visit_DATETIME(self, type_, **kw):
if not isinstance(type_, _DateTimeMixin) or \
type_.format_is_text_affinity:
return super(SQLiteTypeCompiler, self).visit_DATETIME(type_)
else:
return "DATETIME_CHAR"
def visit_DATE(self, type_, **kw):
if not isinstance(type_, _DateTimeMixin) or \
type_.format_is_text_affinity:
return super(SQLiteTypeCompiler, self).visit_DATE(type_)
else:
return "DATE_CHAR"
def visit_TIME(self, type_, **kw):
if not isinstance(type_, _DateTimeMixin) or \
type_.format_is_text_affinity:
return super(SQLiteTypeCompiler, self).visit_TIME(type_)
else:
return "TIME_CHAR"
class SQLiteIdentifierPreparer(compiler.IdentifierPreparer):
reserved_words = set([
'add', 'after', 'all', 'alter', 'analyze', 'and', 'as', 'asc',
'attach', 'autoincrement', 'before', 'begin', 'between', 'by',
'cascade', 'case', 'cast', 'check', 'collate', 'column', 'commit',
'conflict', 'constraint', 'create', 'cross', 'current_date',
'current_time', 'current_timestamp', 'database', 'default',
'deferrable', 'deferred', 'delete', 'desc', 'detach', 'distinct',
'drop', 'each', 'else', 'end', 'escape', 'except', 'exclusive',
'explain', 'false', 'fail', 'for', 'foreign', 'from', 'full', 'glob',
'group', 'having', 'if', 'ignore', 'immediate', 'in', 'index',
'indexed', 'initially', 'inner', 'insert', 'instead', 'intersect',
'into', 'is', 'isnull', 'join', 'key', 'left', 'like', 'limit',
'match', 'natural', 'not', 'notnull', 'null', 'of', 'offset', 'on',
'or', 'order', 'outer', 'plan', 'pragma', 'primary', 'query',
'raise', 'references', 'reindex', 'rename', 'replace', 'restrict',
'right', 'rollback', 'row', 'select', 'set', 'table', 'temp',
'temporary', 'then', 'to', 'transaction', 'trigger', 'true', 'union',
'unique', 'update', 'using', 'vacuum', 'values', 'view', 'virtual',
'when', 'where',
])
def format_index(self, index, use_schema=True, name=None):
"""Prepare a quoted index and schema name."""
if name is None:
name = index.name
result = self.quote(name, index.quote)
if (not self.omit_schema and
use_schema and
getattr(index.table, "schema", None)):
result = self.quote_schema(
index.table.schema, index.table.quote_schema) + "." + result
return result
class SQLiteExecutionContext(default.DefaultExecutionContext):
@util.memoized_property
def _preserve_raw_colnames(self):
return self.execution_options.get("sqlite_raw_colnames", False)
def _translate_colname(self, colname):
# TODO: detect SQLite version 3.10.0 or greater;
# see [ticket:3633]
# adjust for dotted column names. SQLite
# in the case of UNION may store col names as
# "tablename.colname", or if using an attached database,
# "database.tablename.colname", in cursor.description
if not self._preserve_raw_colnames and "." in colname:
return colname.split(".")[-1], colname
else:
return colname, None
class SQLiteDialect(default.DefaultDialect):
name = 'sqlite'
supports_alter = False
supports_unicode_statements = True
supports_unicode_binds = True
supports_default_values = True
supports_empty_insert = False
supports_cast = True
supports_multivalues_insert = True
# TODO: detect version 3.7.16 or greater;
# see [ticket:3634]
supports_right_nested_joins = False
default_paramstyle = 'qmark'
execution_ctx_cls = SQLiteExecutionContext
statement_compiler = SQLiteCompiler
ddl_compiler = SQLiteDDLCompiler
type_compiler = SQLiteTypeCompiler
preparer = SQLiteIdentifierPreparer
ischema_names = ischema_names
colspecs = colspecs
isolation_level = None
supports_cast = True
supports_default_values = True
construct_arguments = [
(sa_schema.Table, {
"autoincrement": False
}),
(sa_schema.Index, {
"where": None,
}),
]
_broken_fk_pragma_quotes = False
def __init__(self, isolation_level=None, native_datetime=False, **kwargs):
default.DefaultDialect.__init__(self, **kwargs)
self.isolation_level = isolation_level
# this flag used by pysqlite dialect, and perhaps others in the
# future, to indicate the driver is handling date/timestamp
# conversions (and perhaps datetime/time as well on some hypothetical
# driver ?)
self.native_datetime = native_datetime
if self.dbapi is not None:
self.supports_default_values = (
self.dbapi.sqlite_version_info >= (3, 3, 8))
self.supports_cast = (
self.dbapi.sqlite_version_info >= (3, 2, 3))
self.supports_multivalues_insert = (
# http://www.sqlite.org/releaselog/3_7_11.html
self.dbapi.sqlite_version_info >= (3, 7, 11))
# see http://www.sqlalchemy.org/trac/ticket/2568
# as well as http://www.sqlite.org/src/info/600482d161
self._broken_fk_pragma_quotes = (
self.dbapi.sqlite_version_info < (3, 6, 14))
_isolation_lookup = {
'READ UNCOMMITTED': 1,
'SERIALIZABLE': 0,
}
def set_isolation_level(self, connection, level):
try:
isolation_level = self._isolation_lookup[level.replace('_', ' ')]
except KeyError:
raise exc.ArgumentError(
"Invalid value '%s' for isolation_level. "
"Valid isolation levels for %s are %s" %
(level, self.name, ", ".join(self._isolation_lookup))
)
cursor = connection.cursor()
cursor.execute("PRAGMA read_uncommitted = %d" % isolation_level)
cursor.close()
def get_isolation_level(self, connection):
cursor = connection.cursor()
cursor.execute('PRAGMA read_uncommitted')
res = cursor.fetchone()
if res:
value = res[0]
else:
# http://www.sqlite.org/changes.html#version_3_3_3
# "Optional READ UNCOMMITTED isolation (instead of the
# default isolation level of SERIALIZABLE) and
# table level locking when database connections
# share a common cache.""
# pre-SQLite 3.3.0 default to 0
value = 0
cursor.close()
if value == 0:
return "SERIALIZABLE"
elif value == 1:
return "READ UNCOMMITTED"
else:
assert False, "Unknown isolation level %s" % value
def on_connect(self):
if self.isolation_level is not None:
def connect(conn):
self.set_isolation_level(conn, self.isolation_level)
return connect
else:
return None
@reflection.cache
def get_table_names(self, connection, schema=None, **kw):
if schema is not None:
qschema = self.identifier_preparer.quote_identifier(schema)
master = '%s.sqlite_master' % qschema
else:
master = "sqlite_master"
s = ("SELECT name FROM %s "
"WHERE type='table' ORDER BY name") % (master,)
rs = connection.execute(s)
return [row[0] for row in rs]
@reflection.cache
def get_temp_table_names(self, connection, **kw):
s = "SELECT name FROM sqlite_temp_master "\
"WHERE type='table' ORDER BY name "
rs = connection.execute(s)
return [row[0] for row in rs]
@reflection.cache
def get_temp_view_names(self, connection, **kw):
s = "SELECT name FROM sqlite_temp_master "\
"WHERE type='view' ORDER BY name "
rs = connection.execute(s)
return [row[0] for row in rs]
def has_table(self, connection, table_name, schema=None):
info = self._get_table_pragma(
connection, "table_info", table_name, schema=schema)
return bool(info)
@reflection.cache
def get_view_names(self, connection, schema=None, **kw):
if schema is not None:
qschema = self.identifier_preparer.quote_identifier(schema)
master = '%s.sqlite_master' % qschema
else:
master = "sqlite_master"
s = ("SELECT name FROM %s "
"WHERE type='view' ORDER BY name") % (master,)
rs = connection.execute(s)
return [row[0] for row in rs]
@reflection.cache
def get_view_definition(self, connection, view_name, schema=None, **kw):
if schema is not None:
qschema = self.identifier_preparer.quote_identifier(schema)
master = '%s.sqlite_master' % qschema
s = ("SELECT sql FROM %s WHERE name = '%s'"
"AND type='view'") % (master, view_name)
rs = connection.execute(s)
else:
try:
s = ("SELECT sql FROM "
" (SELECT * FROM sqlite_master UNION ALL "
" SELECT * FROM sqlite_temp_master) "
"WHERE name = '%s' "
"AND type='view'") % view_name
rs = connection.execute(s)
except exc.DBAPIError:
s = ("SELECT sql FROM sqlite_master WHERE name = '%s' "
"AND type='view'") % view_name
rs = connection.execute(s)
result = rs.fetchall()
if result:
return result[0].sql
@reflection.cache
def get_columns(self, connection, table_name, schema=None, **kw):
info = self._get_table_pragma(
connection, "table_info", table_name, schema=schema)
columns = []
for row in info:
(name, type_, nullable, default, primary_key) = (
row[1], row[2].upper(), not row[3], row[4], row[5])
columns.append(self._get_column_info(name, type_, nullable,
default, primary_key))
return columns
def _get_column_info(self, name, type_, nullable, default, primary_key):
coltype = self._resolve_type_affinity(type_)
if default is not None:
default = util.text_type(default)
return {
'name': name,
'type': coltype,
'nullable': nullable,
'default': default,
'autoincrement': default is None,
'primary_key': primary_key,
}
def _resolve_type_affinity(self, type_):
"""Return a data type from a reflected column, using affinity tules.
SQLite's goal for universal compatibility introduces some complexity
during reflection, as a column's defined type might not actually be a
type that SQLite understands - or indeed, my not be defined *at all*.
Internally, SQLite handles this with a 'data type affinity' for each
column definition, mapping to one of 'TEXT', 'NUMERIC', 'INTEGER',
'REAL', or 'NONE' (raw bits). The algorithm that determines this is
listed in http://www.sqlite.org/datatype3.html section 2.1.
This method allows SQLAlchemy to support that algorithm, while still
providing access to smarter reflection utilities by regcognizing
column definitions that SQLite only supports through affinity (like
DATE and DOUBLE).
"""
match = re.match(r'([\w ]+)(\(.*?\))?', type_)
if match:
coltype = match.group(1)
args = match.group(2)
else:
coltype = ''
args = ''
if coltype in self.ischema_names:
coltype = self.ischema_names[coltype]
elif 'INT' in coltype:
coltype = sqltypes.INTEGER
elif 'CHAR' in coltype or 'CLOB' in coltype or 'TEXT' in coltype:
coltype = sqltypes.TEXT
elif 'BLOB' in coltype or not coltype:
coltype = sqltypes.NullType
elif 'REAL' in coltype or 'FLOA' in coltype or 'DOUB' in coltype:
coltype = sqltypes.REAL
else:
coltype = sqltypes.NUMERIC
if args is not None:
args = re.findall(r'(\d+)', args)
try:
coltype = coltype(*[int(a) for a in args])
except TypeError:
util.warn(
"Could not instantiate type %s with "
"reflected arguments %s; using no arguments." %
(coltype, args))
coltype = coltype()
else:
coltype = coltype()
return coltype
@reflection.cache
def get_pk_constraint(self, connection, table_name, schema=None, **kw):
cols = self.get_columns(connection, table_name, schema, **kw)
pkeys = []
for col in cols:
if col['primary_key']:
pkeys.append(col['name'])
return {'constrained_columns': pkeys, 'name': None}
@reflection.cache
def get_foreign_keys(self, connection, table_name, schema=None, **kw):
# sqlite makes this *extremely difficult*.
# First, use the pragma to get the actual FKs.
pragma_fks = self._get_table_pragma(
connection, "foreign_key_list",
table_name, schema=schema
)
fks = {}
for row in pragma_fks:
(numerical_id, rtbl, lcol, rcol) = (
row[0], row[2], row[3], row[4])
if rcol is None:
rcol = lcol
if self._broken_fk_pragma_quotes:
rtbl = re.sub(r'^[\"\[`\']|[\"\]`\']$', '', rtbl)
if numerical_id in fks:
fk = fks[numerical_id]
else:
fk = fks[numerical_id] = {
'name': None,
'constrained_columns': [],
'referred_schema': None,
'referred_table': rtbl,
'referred_columns': [],
}
fks[numerical_id] = fk
fk['constrained_columns'].append(lcol)
fk['referred_columns'].append(rcol)
def fk_sig(constrained_columns, referred_table, referred_columns):
return tuple(constrained_columns) + (referred_table,) + \
tuple(referred_columns)
# then, parse the actual SQL and attempt to find DDL that matches
# the names as well. SQLite saves the DDL in whatever format
# it was typed in as, so need to be liberal here.
keys_by_signature = dict(
(
fk_sig(
fk['constrained_columns'],
fk['referred_table'], fk['referred_columns']),
fk
) for fk in fks.values()
)
table_data = self._get_table_sql(connection, table_name, schema=schema)
if table_data is None:
# system tables, etc.
return []
def parse_fks():
FK_PATTERN = (
'(?:CONSTRAINT (\w+) +)?'
'FOREIGN KEY *\( *(.+?) *\) +'
'REFERENCES +(?:(?:"(.+?)")|([a-z0-9_]+)) *\((.+?)\)'
)
for match in re.finditer(FK_PATTERN, table_data, re.I):
(
constraint_name, constrained_columns,
referred_quoted_name, referred_name,
referred_columns) = match.group(1, 2, 3, 4, 5)
constrained_columns = list(
self._find_cols_in_sig(constrained_columns))
if not referred_columns:
referred_columns = constrained_columns
else:
referred_columns = list(
self._find_cols_in_sig(referred_columns))
referred_name = referred_quoted_name or referred_name
yield (
constraint_name, constrained_columns,
referred_name, referred_columns)
fkeys = []
for (
constraint_name, constrained_columns,
referred_name, referred_columns) in parse_fks():
sig = fk_sig(
constrained_columns, referred_name, referred_columns)
if sig not in keys_by_signature:
util.warn(
"WARNING: SQL-parsed foreign key constraint "
"'%s' could not be located in PRAGMA "
"foreign_keys for table %s" % (
sig,
table_name
))
continue
key = keys_by_signature.pop(sig)
key['name'] = constraint_name
fkeys.append(key)
# assume the remainders are the unnamed, inline constraints, just
# use them as is as it's extremely difficult to parse inline
# constraints
fkeys.extend(keys_by_signature.values())
return fkeys
def _find_cols_in_sig(self, sig):
for match in re.finditer(r'(?:"(.+?)")|([a-z0-9_]+)', sig, re.I):
yield match.group(1) or match.group(2)
@reflection.cache
def get_unique_constraints(self, connection, table_name,
schema=None, **kw):
auto_index_by_sig = {}
for idx in self.get_indexes(
connection, table_name, schema=schema,
include_auto_indexes=True, **kw):
if not idx['name'].startswith("sqlite_autoindex"):
continue
sig = tuple(idx['column_names'])
auto_index_by_sig[sig] = idx
table_data = self._get_table_sql(
connection, table_name, schema=schema, **kw)
if not table_data:
return []
unique_constraints = []
def parse_uqs():
UNIQUE_PATTERN = '(?:CONSTRAINT "?(.+?)"? +)?UNIQUE *\((.+?)\)'
INLINE_UNIQUE_PATTERN = (
'(?:(".+?")|([a-z0-9]+)) '
'+[a-z0-9_ ]+? +UNIQUE')
for match in re.finditer(UNIQUE_PATTERN, table_data, re.I):
name, cols = match.group(1, 2)
yield name, list(self._find_cols_in_sig(cols))
# we need to match inlines as well, as we seek to differentiate
# a UNIQUE constraint from a UNIQUE INDEX, even though these
# are kind of the same thing :)
for match in re.finditer(INLINE_UNIQUE_PATTERN, table_data, re.I):
cols = list(
self._find_cols_in_sig(match.group(1) or match.group(2)))
yield None, cols
for name, cols in parse_uqs():
sig = tuple(cols)
if sig in auto_index_by_sig:
auto_index_by_sig.pop(sig)
parsed_constraint = {
'name': name,
'column_names': cols
}
unique_constraints.append(parsed_constraint)
# NOTE: auto_index_by_sig might not be empty here,
# the PRIMARY KEY may have an entry.
return unique_constraints
@reflection.cache
def get_indexes(self, connection, table_name, schema=None, **kw):
pragma_indexes = self._get_table_pragma(
connection, "index_list", table_name, schema=schema)
indexes = []
include_auto_indexes = kw.pop('include_auto_indexes', False)
for row in pragma_indexes:
# ignore implicit primary key index.
# http://www.mail-archive.com/sqlite-users@sqlite.org/msg30517.html
if (not include_auto_indexes and
row[1].startswith('sqlite_autoindex')):
continue
indexes.append(dict(name=row[1], column_names=[], unique=row[2]))
# loop thru unique indexes to get the column names.
for idx in indexes:
pragma_index = self._get_table_pragma(
connection, "index_info", idx['name'])
for row in pragma_index:
idx['column_names'].append(row[2])
return indexes
@reflection.cache
def _get_table_sql(self, connection, table_name, schema=None, **kw):
try:
s = ("SELECT sql FROM "
" (SELECT * FROM sqlite_master UNION ALL "
" SELECT * FROM sqlite_temp_master) "
"WHERE name = '%s' "
"AND type = 'table'") % table_name
rs = connection.execute(s)
except exc.DBAPIError:
s = ("SELECT sql FROM sqlite_master WHERE name = '%s' "
"AND type = 'table'") % table_name
rs = connection.execute(s)
return rs.scalar()
def _get_table_pragma(self, connection, pragma, table_name, schema=None):
quote = self.identifier_preparer.quote_identifier
if schema is not None:
statement = "PRAGMA %s." % quote(schema)
else:
statement = "PRAGMA "
qtable = quote(table_name)
statement = "%s%s(%s)" % (statement, pragma, qtable)
cursor = connection.execute(statement)
if not cursor._soft_closed:
# work around SQLite issue whereby cursor.description
# is blank when PRAGMA returns no rows:
# http://www.sqlite.org/cvstrac/tktview?tn=1884
result = cursor.fetchall()
else:
result = []
return result
|