300 lines
12 KiB
Python
300 lines
12 KiB
Python
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import datetime
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import decimal
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import uuid
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from django.conf import settings
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from django.core.exceptions import FieldError
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from django.db import utils
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from django.db.backends.base.operations import BaseDatabaseOperations
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from django.db.models import aggregates, fields
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from django.db.models.expressions import Col
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from django.utils import timezone
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from django.utils.dateparse import parse_date, parse_datetime, parse_time
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from django.utils.duration import duration_microseconds
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class DatabaseOperations(BaseDatabaseOperations):
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cast_char_field_without_max_length = 'text'
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cast_data_types = {
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'DateField': 'TEXT',
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'DateTimeField': 'TEXT',
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}
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explain_prefix = 'EXPLAIN QUERY PLAN'
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def bulk_batch_size(self, fields, objs):
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"""
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SQLite has a compile-time default (SQLITE_LIMIT_VARIABLE_NUMBER) of
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999 variables per query.
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If there's only a single field to insert, the limit is 500
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(SQLITE_MAX_COMPOUND_SELECT).
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"""
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if len(fields) == 1:
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return 500
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elif len(fields) > 1:
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return self.connection.features.max_query_params // len(fields)
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else:
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return len(objs)
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def check_expression_support(self, expression):
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bad_fields = (fields.DateField, fields.DateTimeField, fields.TimeField)
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bad_aggregates = (aggregates.Sum, aggregates.Avg, aggregates.Variance, aggregates.StdDev)
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if isinstance(expression, bad_aggregates):
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for expr in expression.get_source_expressions():
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try:
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output_field = expr.output_field
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except FieldError:
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# Not every subexpression has an output_field which is fine
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# to ignore.
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pass
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else:
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if isinstance(output_field, bad_fields):
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raise utils.NotSupportedError(
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'You cannot use Sum, Avg, StdDev, and Variance '
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'aggregations on date/time fields in sqlite3 '
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'since date/time is saved as text.'
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)
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def date_extract_sql(self, lookup_type, field_name):
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"""
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Support EXTRACT with a user-defined function django_date_extract()
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that's registered in connect(). Use single quotes because this is a
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string and could otherwise cause a collision with a field name.
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"""
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return "django_date_extract('%s', %s)" % (lookup_type.lower(), field_name)
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def date_interval_sql(self, timedelta):
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return str(duration_microseconds(timedelta))
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def format_for_duration_arithmetic(self, sql):
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"""Do nothing since formatting is handled in the custom function."""
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return sql
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def date_trunc_sql(self, lookup_type, field_name):
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return "django_date_trunc('%s', %s)" % (lookup_type.lower(), field_name)
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def time_trunc_sql(self, lookup_type, field_name):
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return "django_time_trunc('%s', %s)" % (lookup_type.lower(), field_name)
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def _convert_tzname_to_sql(self, tzname):
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return "'%s'" % tzname if settings.USE_TZ else 'NULL'
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def datetime_cast_date_sql(self, field_name, tzname):
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return "django_datetime_cast_date(%s, %s)" % (
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field_name, self._convert_tzname_to_sql(tzname),
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)
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def datetime_cast_time_sql(self, field_name, tzname):
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return "django_datetime_cast_time(%s, %s)" % (
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field_name, self._convert_tzname_to_sql(tzname),
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)
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def datetime_extract_sql(self, lookup_type, field_name, tzname):
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return "django_datetime_extract('%s', %s, %s)" % (
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lookup_type.lower(), field_name, self._convert_tzname_to_sql(tzname),
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)
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def datetime_trunc_sql(self, lookup_type, field_name, tzname):
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return "django_datetime_trunc('%s', %s, %s)" % (
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lookup_type.lower(), field_name, self._convert_tzname_to_sql(tzname),
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)
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def time_extract_sql(self, lookup_type, field_name):
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return "django_time_extract('%s', %s)" % (lookup_type.lower(), field_name)
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def pk_default_value(self):
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return "NULL"
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def _quote_params_for_last_executed_query(self, params):
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"""
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Only for last_executed_query! Don't use this to execute SQL queries!
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"""
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# This function is limited both by SQLITE_LIMIT_VARIABLE_NUMBER (the
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# number of parameters, default = 999) and SQLITE_MAX_COLUMN (the
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# number of return values, default = 2000). Since Python's sqlite3
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# module doesn't expose the get_limit() C API, assume the default
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# limits are in effect and split the work in batches if needed.
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BATCH_SIZE = 999
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if len(params) > BATCH_SIZE:
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results = ()
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for index in range(0, len(params), BATCH_SIZE):
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chunk = params[index:index + BATCH_SIZE]
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results += self._quote_params_for_last_executed_query(chunk)
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return results
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sql = 'SELECT ' + ', '.join(['QUOTE(?)'] * len(params))
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# Bypass Django's wrappers and use the underlying sqlite3 connection
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# to avoid logging this query - it would trigger infinite recursion.
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cursor = self.connection.connection.cursor()
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# Native sqlite3 cursors cannot be used as context managers.
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try:
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return cursor.execute(sql, params).fetchone()
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finally:
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cursor.close()
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def last_executed_query(self, cursor, sql, params):
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# Python substitutes parameters in Modules/_sqlite/cursor.c with:
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# pysqlite_statement_bind_parameters(self->statement, parameters, allow_8bit_chars);
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# Unfortunately there is no way to reach self->statement from Python,
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# so we quote and substitute parameters manually.
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if params:
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if isinstance(params, (list, tuple)):
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params = self._quote_params_for_last_executed_query(params)
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else:
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values = tuple(params.values())
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values = self._quote_params_for_last_executed_query(values)
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params = dict(zip(params, values))
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return sql % params
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# For consistency with SQLiteCursorWrapper.execute(), just return sql
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# when there are no parameters. See #13648 and #17158.
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else:
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return sql
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def quote_name(self, name):
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if name.startswith('"') and name.endswith('"'):
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return name # Quoting once is enough.
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return '"%s"' % name
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def no_limit_value(self):
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return -1
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def sql_flush(self, style, tables, sequences, allow_cascade=False):
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sql = ['%s %s %s;' % (
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style.SQL_KEYWORD('DELETE'),
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style.SQL_KEYWORD('FROM'),
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style.SQL_FIELD(self.quote_name(table))
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) for table in tables]
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# Note: No requirement for reset of auto-incremented indices (cf. other
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# sql_flush() implementations). Just return SQL at this point
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return sql
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def execute_sql_flush(self, using, sql_list):
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# To prevent possible violation of foreign key constraints, deactivate
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# constraints outside of the transaction created in super().
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with self.connection.constraint_checks_disabled():
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super().execute_sql_flush(using, sql_list)
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def adapt_datetimefield_value(self, value):
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if value is None:
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return None
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# Expression values are adapted by the database.
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if hasattr(value, 'resolve_expression'):
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return value
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# SQLite doesn't support tz-aware datetimes
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if timezone.is_aware(value):
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if settings.USE_TZ:
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value = timezone.make_naive(value, self.connection.timezone)
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else:
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raise ValueError("SQLite backend does not support timezone-aware datetimes when USE_TZ is False.")
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return str(value)
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def adapt_timefield_value(self, value):
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if value is None:
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return None
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# Expression values are adapted by the database.
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if hasattr(value, 'resolve_expression'):
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return value
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# SQLite doesn't support tz-aware datetimes
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if timezone.is_aware(value):
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raise ValueError("SQLite backend does not support timezone-aware times.")
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return str(value)
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def get_db_converters(self, expression):
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converters = super().get_db_converters(expression)
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internal_type = expression.output_field.get_internal_type()
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if internal_type == 'DateTimeField':
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converters.append(self.convert_datetimefield_value)
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elif internal_type == 'DateField':
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converters.append(self.convert_datefield_value)
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elif internal_type == 'TimeField':
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converters.append(self.convert_timefield_value)
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elif internal_type == 'DecimalField':
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converters.append(self.get_decimalfield_converter(expression))
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elif internal_type == 'UUIDField':
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converters.append(self.convert_uuidfield_value)
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elif internal_type in ('NullBooleanField', 'BooleanField'):
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converters.append(self.convert_booleanfield_value)
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return converters
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def convert_datetimefield_value(self, value, expression, connection):
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if value is not None:
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if not isinstance(value, datetime.datetime):
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value = parse_datetime(value)
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if settings.USE_TZ and not timezone.is_aware(value):
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value = timezone.make_aware(value, self.connection.timezone)
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return value
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def convert_datefield_value(self, value, expression, connection):
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if value is not None:
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if not isinstance(value, datetime.date):
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value = parse_date(value)
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return value
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def convert_timefield_value(self, value, expression, connection):
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if value is not None:
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if not isinstance(value, datetime.time):
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value = parse_time(value)
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return value
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def get_decimalfield_converter(self, expression):
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# SQLite stores only 15 significant digits. Digits coming from
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# float inaccuracy must be removed.
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create_decimal = decimal.Context(prec=15).create_decimal_from_float
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if isinstance(expression, Col):
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quantize_value = decimal.Decimal(1).scaleb(-expression.output_field.decimal_places)
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def converter(value, expression, connection):
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if value is not None:
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return create_decimal(value).quantize(quantize_value, context=expression.output_field.context)
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else:
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def converter(value, expression, connection):
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if value is not None:
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return create_decimal(value)
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return converter
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def convert_uuidfield_value(self, value, expression, connection):
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if value is not None:
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value = uuid.UUID(value)
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return value
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def convert_booleanfield_value(self, value, expression, connection):
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return bool(value) if value in (1, 0) else value
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def bulk_insert_sql(self, fields, placeholder_rows):
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return " UNION ALL ".join(
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"SELECT %s" % ", ".join(row)
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for row in placeholder_rows
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)
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def combine_expression(self, connector, sub_expressions):
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# SQLite doesn't have a power function, so we fake it with a
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# user-defined function django_power that's registered in connect().
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if connector == '^':
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return 'django_power(%s)' % ','.join(sub_expressions)
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return super().combine_expression(connector, sub_expressions)
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def combine_duration_expression(self, connector, sub_expressions):
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if connector not in ['+', '-']:
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raise utils.DatabaseError('Invalid connector for timedelta: %s.' % connector)
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fn_params = ["'%s'" % connector] + sub_expressions
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if len(fn_params) > 3:
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raise ValueError('Too many params for timedelta operations.')
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return "django_format_dtdelta(%s)" % ', '.join(fn_params)
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def integer_field_range(self, internal_type):
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# SQLite doesn't enforce any integer constraints
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return (None, None)
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def subtract_temporals(self, internal_type, lhs, rhs):
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lhs_sql, lhs_params = lhs
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rhs_sql, rhs_params = rhs
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if internal_type == 'TimeField':
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return "django_time_diff(%s, %s)" % (lhs_sql, rhs_sql), lhs_params + rhs_params
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return "django_timestamp_diff(%s, %s)" % (lhs_sql, rhs_sql), lhs_params + rhs_params
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