205 lines
8.5 KiB
Python
205 lines
8.5 KiB
Python
from __future__ import unicode_literals
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import datetime
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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, ImproperlyConfigured
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from django.db import utils
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from django.db.backends import utils as backend_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.utils import six, timezone
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from django.utils.dateparse import parse_date, parse_time
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from django.utils.duration import duration_string
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from .utils import parse_datetime_with_timezone_support
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try:
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import pytz
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except ImportError:
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pytz = None
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class DatabaseOperations(BaseDatabaseOperations):
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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 is just single field to insert, then we can hit another
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limit, SQLITE_MAX_COMPOUND_SELECT which defaults to 500.
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"""
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limit = 999 if len(fields) > 1 else 500
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return (limit // len(fields)) if len(fields) > 0 else 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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try:
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output_field = expression.input_field.output_field
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if isinstance(output_field, bad_fields):
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raise NotImplementedError(
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'You cannot use Sum, Avg, StdDev and Variance aggregations '
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'on date/time fields in sqlite3 '
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'since date/time is saved as text.')
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except FieldError:
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# not every sub-expression has an output_field which is fine to
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# ignore
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pass
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def date_extract_sql(self, lookup_type, field_name):
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# sqlite doesn't support extract, so we fake it with the user-defined
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# function django_date_extract that's registered in connect(). Note that
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# single quotes are used because this is a string (and could otherwise
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# cause a collision with a field name).
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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 "'%s'" % duration_string(timedelta), []
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def format_for_duration_arithmetic(self, sql):
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"""Do nothing here, we will handle it 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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# sqlite doesn't support DATE_TRUNC, so we fake it with a user-defined
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# function django_date_trunc that's registered in connect(). Note that
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# single quotes are used because this is a string (and could otherwise
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# cause a collision with a field name).
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return "django_date_trunc('%s', %s)" % (lookup_type.lower(), field_name)
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def datetime_extract_sql(self, lookup_type, field_name, tzname):
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# Same comment as in date_extract_sql.
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if settings.USE_TZ:
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if pytz is None:
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raise ImproperlyConfigured("This query requires pytz, "
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"but it isn't installed.")
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return "django_datetime_extract('%s', %s, %%s)" % (
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lookup_type.lower(), field_name), [tzname]
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def datetime_trunc_sql(self, lookup_type, field_name, tzname):
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# Same comment as in date_trunc_sql.
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if settings.USE_TZ:
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if pytz is None:
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raise ImproperlyConfigured("This query requires pytz, "
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"but it isn't installed.")
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return "django_datetime_trunc('%s', %s, %%s)" % (
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lookup_type.lower(), field_name), [tzname]
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def drop_foreignkey_sql(self):
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return ""
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def pk_default_value(self):
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return "NULL"
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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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# NB: The generated SQL below is specific to SQLite
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# Note: The DELETE FROM... SQL generated below works for SQLite databases
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# because constraints don't exist
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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 value_to_db_datetime(self, value):
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if value is None:
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return None
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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 = value.astimezone(timezone.utc).replace(tzinfo=None)
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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 six.text_type(value)
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def value_to_db_time(self, value):
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if value is None:
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return None
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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 six.text_type(value)
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def get_db_converters(self, expression):
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converters = super(DatabaseOperations, self).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.convert_decimalfield_value)
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elif internal_type == 'UUIDField':
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converters.append(self.convert_uuidfield_value)
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return converters
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def convert_decimalfield_value(self, value, expression, connection, context):
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return backend_utils.typecast_decimal(expression.output_field.format_number(value))
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def convert_datefield_value(self, value, expression, connection, context):
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if value is not None and 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_datetimefield_value(self, value, expression, connection, context):
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if value is not None and not isinstance(value, datetime.datetime):
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value = parse_datetime_with_timezone_support(value)
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return value
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def convert_timefield_value(self, value, expression, connection, context):
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if value is not None and not isinstance(value, datetime.time):
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value = parse_time(value)
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return value
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def convert_uuidfield_value(self, value, expression, connection, context):
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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 bulk_insert_sql(self, fields, num_values):
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res = []
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res.append("SELECT %s" % ", ".join(
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"%%s AS %s" % self.quote_name(f.column) for f in fields
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))
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res.extend(["UNION ALL SELECT %s" % ", ".join(["%s"] * len(fields))] * (num_values - 1))
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return " ".join(res)
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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(DatabaseOperations, self).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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