435 lines
17 KiB
Python
435 lines
17 KiB
Python
from collections import namedtuple
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import sqlparse
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from django.db import DatabaseError
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from django.db.backends.base.introspection import BaseDatabaseIntrospection
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from django.db.backends.base.introspection import FieldInfo as BaseFieldInfo
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from django.db.backends.base.introspection import TableInfo
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from django.db.models import Index
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from django.utils.regex_helper import _lazy_re_compile
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FieldInfo = namedtuple(
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"FieldInfo", BaseFieldInfo._fields + ("pk", "has_json_constraint")
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)
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field_size_re = _lazy_re_compile(r"^\s*(?:var)?char\s*\(\s*(\d+)\s*\)\s*$")
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def get_field_size(name):
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"""Extract the size number from a "varchar(11)" type name"""
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m = field_size_re.search(name)
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return int(m[1]) if m else None
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# This light wrapper "fakes" a dictionary interface, because some SQLite data
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# types include variables in them -- e.g. "varchar(30)" -- and can't be matched
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# as a simple dictionary lookup.
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class FlexibleFieldLookupDict:
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# Maps SQL types to Django Field types. Some of the SQL types have multiple
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# entries here because SQLite allows for anything and doesn't normalize the
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# field type; it uses whatever was given.
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base_data_types_reverse = {
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"bool": "BooleanField",
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"boolean": "BooleanField",
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"smallint": "SmallIntegerField",
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"smallint unsigned": "PositiveSmallIntegerField",
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"smallinteger": "SmallIntegerField",
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"int": "IntegerField",
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"integer": "IntegerField",
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"bigint": "BigIntegerField",
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"integer unsigned": "PositiveIntegerField",
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"bigint unsigned": "PositiveBigIntegerField",
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"decimal": "DecimalField",
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"real": "FloatField",
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"text": "TextField",
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"char": "CharField",
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"varchar": "CharField",
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"blob": "BinaryField",
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"date": "DateField",
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"datetime": "DateTimeField",
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"time": "TimeField",
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}
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def __getitem__(self, key):
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key = key.lower().split("(", 1)[0].strip()
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return self.base_data_types_reverse[key]
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class DatabaseIntrospection(BaseDatabaseIntrospection):
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data_types_reverse = FlexibleFieldLookupDict()
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def get_field_type(self, data_type, description):
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field_type = super().get_field_type(data_type, description)
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if description.pk and field_type in {
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"BigIntegerField",
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"IntegerField",
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"SmallIntegerField",
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}:
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# No support for BigAutoField or SmallAutoField as SQLite treats
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# all integer primary keys as signed 64-bit integers.
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return "AutoField"
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if description.has_json_constraint:
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return "JSONField"
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return field_type
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def get_table_list(self, cursor):
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"""Return a list of table and view names in the current database."""
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# Skip the sqlite_sequence system table used for autoincrement key
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# generation.
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cursor.execute(
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"""
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SELECT name, type FROM sqlite_master
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WHERE type in ('table', 'view') AND NOT name='sqlite_sequence'
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ORDER BY name"""
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)
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return [TableInfo(row[0], row[1][0]) for row in cursor.fetchall()]
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def get_table_description(self, cursor, table_name):
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"""
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Return a description of the table with the DB-API cursor.description
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interface.
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"""
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cursor.execute(
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"PRAGMA table_info(%s)" % self.connection.ops.quote_name(table_name)
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)
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table_info = cursor.fetchall()
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if not table_info:
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raise DatabaseError(f"Table {table_name} does not exist (empty pragma).")
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collations = self._get_column_collations(cursor, table_name)
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json_columns = set()
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if self.connection.features.can_introspect_json_field:
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for line in table_info:
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column = line[1]
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json_constraint_sql = '%%json_valid("%s")%%' % column
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has_json_constraint = cursor.execute(
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"""
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SELECT sql
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FROM sqlite_master
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WHERE
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type = 'table' AND
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name = %s AND
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sql LIKE %s
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""",
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[table_name, json_constraint_sql],
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).fetchone()
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if has_json_constraint:
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json_columns.add(column)
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return [
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FieldInfo(
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name,
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data_type,
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get_field_size(data_type),
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None,
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None,
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None,
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not notnull,
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default,
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collations.get(name),
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pk == 1,
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name in json_columns,
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)
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for cid, name, data_type, notnull, default, pk in table_info
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]
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def get_sequences(self, cursor, table_name, table_fields=()):
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pk_col = self.get_primary_key_column(cursor, table_name)
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return [{"table": table_name, "column": pk_col}]
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def get_relations(self, cursor, table_name):
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"""
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Return a dictionary of {column_name: (ref_column_name, ref_table_name)}
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representing all foreign keys in the given table.
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"""
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cursor.execute(
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"PRAGMA foreign_key_list(%s)" % self.connection.ops.quote_name(table_name)
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)
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return {
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column_name: (ref_column_name, ref_table_name)
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for (
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_,
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_,
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ref_table_name,
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column_name,
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ref_column_name,
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*_,
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) in cursor.fetchall()
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}
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def get_primary_key_columns(self, cursor, table_name):
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cursor.execute(
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"PRAGMA table_info(%s)" % self.connection.ops.quote_name(table_name)
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)
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return [name for _, name, *_, pk in cursor.fetchall() if pk]
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def _parse_column_or_constraint_definition(self, tokens, columns):
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token = None
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is_constraint_definition = None
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field_name = None
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constraint_name = None
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unique = False
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unique_columns = []
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check = False
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check_columns = []
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braces_deep = 0
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for token in tokens:
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if token.match(sqlparse.tokens.Punctuation, "("):
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braces_deep += 1
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elif token.match(sqlparse.tokens.Punctuation, ")"):
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braces_deep -= 1
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if braces_deep < 0:
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# End of columns and constraints for table definition.
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break
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elif braces_deep == 0 and token.match(sqlparse.tokens.Punctuation, ","):
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# End of current column or constraint definition.
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break
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# Detect column or constraint definition by first token.
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if is_constraint_definition is None:
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is_constraint_definition = token.match(
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sqlparse.tokens.Keyword, "CONSTRAINT"
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)
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if is_constraint_definition:
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continue
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if is_constraint_definition:
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# Detect constraint name by second token.
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if constraint_name is None:
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if token.ttype in (sqlparse.tokens.Name, sqlparse.tokens.Keyword):
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constraint_name = token.value
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elif token.ttype == sqlparse.tokens.Literal.String.Symbol:
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constraint_name = token.value[1:-1]
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# Start constraint columns parsing after UNIQUE keyword.
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if token.match(sqlparse.tokens.Keyword, "UNIQUE"):
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unique = True
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unique_braces_deep = braces_deep
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elif unique:
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if unique_braces_deep == braces_deep:
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if unique_columns:
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# Stop constraint parsing.
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unique = False
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continue
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if token.ttype in (sqlparse.tokens.Name, sqlparse.tokens.Keyword):
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unique_columns.append(token.value)
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elif token.ttype == sqlparse.tokens.Literal.String.Symbol:
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unique_columns.append(token.value[1:-1])
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else:
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# Detect field name by first token.
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if field_name is None:
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if token.ttype in (sqlparse.tokens.Name, sqlparse.tokens.Keyword):
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field_name = token.value
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elif token.ttype == sqlparse.tokens.Literal.String.Symbol:
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field_name = token.value[1:-1]
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if token.match(sqlparse.tokens.Keyword, "UNIQUE"):
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unique_columns = [field_name]
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# Start constraint columns parsing after CHECK keyword.
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if token.match(sqlparse.tokens.Keyword, "CHECK"):
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check = True
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check_braces_deep = braces_deep
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elif check:
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if check_braces_deep == braces_deep:
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if check_columns:
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# Stop constraint parsing.
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check = False
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continue
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if token.ttype in (sqlparse.tokens.Name, sqlparse.tokens.Keyword):
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if token.value in columns:
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check_columns.append(token.value)
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elif token.ttype == sqlparse.tokens.Literal.String.Symbol:
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if token.value[1:-1] in columns:
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check_columns.append(token.value[1:-1])
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unique_constraint = (
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{
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"unique": True,
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"columns": unique_columns,
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"primary_key": False,
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"foreign_key": None,
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"check": False,
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"index": False,
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}
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if unique_columns
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else None
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)
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check_constraint = (
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{
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"check": True,
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"columns": check_columns,
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"primary_key": False,
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"unique": False,
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"foreign_key": None,
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"index": False,
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}
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if check_columns
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else None
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)
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return constraint_name, unique_constraint, check_constraint, token
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def _parse_table_constraints(self, sql, columns):
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# Check constraint parsing is based of SQLite syntax diagram.
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# https://www.sqlite.org/syntaxdiagrams.html#table-constraint
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statement = sqlparse.parse(sql)[0]
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constraints = {}
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unnamed_constrains_index = 0
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tokens = (token for token in statement.flatten() if not token.is_whitespace)
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# Go to columns and constraint definition
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for token in tokens:
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if token.match(sqlparse.tokens.Punctuation, "("):
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break
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# Parse columns and constraint definition
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while True:
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(
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constraint_name,
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unique,
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check,
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end_token,
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) = self._parse_column_or_constraint_definition(tokens, columns)
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if unique:
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if constraint_name:
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constraints[constraint_name] = unique
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else:
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unnamed_constrains_index += 1
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constraints[
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"__unnamed_constraint_%s__" % unnamed_constrains_index
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] = unique
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if check:
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if constraint_name:
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constraints[constraint_name] = check
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else:
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unnamed_constrains_index += 1
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constraints[
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"__unnamed_constraint_%s__" % unnamed_constrains_index
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] = check
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if end_token.match(sqlparse.tokens.Punctuation, ")"):
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break
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return constraints
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def get_constraints(self, cursor, table_name):
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"""
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Retrieve any constraints or keys (unique, pk, fk, check, index) across
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one or more columns.
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"""
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constraints = {}
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# Find inline check constraints.
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try:
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table_schema = cursor.execute(
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"SELECT sql FROM sqlite_master WHERE type='table' and name=%s"
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% (self.connection.ops.quote_name(table_name),)
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).fetchone()[0]
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except TypeError:
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# table_name is a view.
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pass
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else:
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columns = {
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info.name for info in self.get_table_description(cursor, table_name)
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}
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constraints.update(self._parse_table_constraints(table_schema, columns))
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# Get the index info
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cursor.execute(
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"PRAGMA index_list(%s)" % self.connection.ops.quote_name(table_name)
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)
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for row in cursor.fetchall():
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# SQLite 3.8.9+ has 5 columns, however older versions only give 3
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# columns. Discard last 2 columns if there.
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number, index, unique = row[:3]
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cursor.execute(
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"SELECT sql FROM sqlite_master "
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"WHERE type='index' AND name=%s" % self.connection.ops.quote_name(index)
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)
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# There's at most one row.
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(sql,) = cursor.fetchone() or (None,)
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# Inline constraints are already detected in
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# _parse_table_constraints(). The reasons to avoid fetching inline
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# constraints from `PRAGMA index_list` are:
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# - Inline constraints can have a different name and information
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# than what `PRAGMA index_list` gives.
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# - Not all inline constraints may appear in `PRAGMA index_list`.
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if not sql:
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# An inline constraint
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continue
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# Get the index info for that index
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cursor.execute(
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"PRAGMA index_info(%s)" % self.connection.ops.quote_name(index)
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)
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for index_rank, column_rank, column in cursor.fetchall():
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if index not in constraints:
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constraints[index] = {
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"columns": [],
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"primary_key": False,
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"unique": bool(unique),
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"foreign_key": None,
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"check": False,
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"index": True,
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}
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constraints[index]["columns"].append(column)
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# Add type and column orders for indexes
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if constraints[index]["index"]:
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# SQLite doesn't support any index type other than b-tree
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constraints[index]["type"] = Index.suffix
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orders = self._get_index_columns_orders(sql)
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if orders is not None:
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constraints[index]["orders"] = orders
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# Get the PK
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pk_columns = self.get_primary_key_columns(cursor, table_name)
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if pk_columns:
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# SQLite doesn't actually give a name to the PK constraint,
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# so we invent one. This is fine, as the SQLite backend never
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# deletes PK constraints by name, as you can't delete constraints
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# in SQLite; we remake the table with a new PK instead.
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constraints["__primary__"] = {
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"columns": pk_columns,
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"primary_key": True,
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"unique": False, # It's not actually a unique constraint.
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"foreign_key": None,
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"check": False,
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"index": False,
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}
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relations = enumerate(self.get_relations(cursor, table_name).items())
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constraints.update(
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{
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f"fk_{index}": {
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"columns": [column_name],
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"primary_key": False,
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"unique": False,
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"foreign_key": (ref_table_name, ref_column_name),
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"check": False,
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"index": False,
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}
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for index, (column_name, (ref_column_name, ref_table_name)) in relations
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}
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)
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return constraints
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def _get_index_columns_orders(self, sql):
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tokens = sqlparse.parse(sql)[0]
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for token in tokens:
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if isinstance(token, sqlparse.sql.Parenthesis):
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columns = str(token).strip("()").split(", ")
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return ["DESC" if info.endswith("DESC") else "ASC" for info in columns]
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return None
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def _get_column_collations(self, cursor, table_name):
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row = cursor.execute(
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"""
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SELECT sql
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FROM sqlite_master
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WHERE type = 'table' AND name = %s
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""",
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[table_name],
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).fetchone()
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if not row:
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return {}
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sql = row[0]
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columns = str(sqlparse.parse(sql)[0][-1]).strip("()").split(", ")
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collations = {}
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for column in columns:
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tokens = column[1:].split()
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column_name = tokens[0].strip('"')
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for index, token in enumerate(tokens):
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if token == "COLLATE":
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collation = tokens[index + 1]
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break
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else:
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collation = None
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collations[column_name] = collation
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return collations
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