Method check

django/db/models/query_utils.py:171–201

Do a database query to check if the expressions of the Q instance matches against the expressions.

(self, against, using=DEFAULT_DB_ALIAS)

                yield child

    def check(self, against, using=DEFAULT_DB_ALIAS):
        """
        Do a database query to check if the expressions of the Q instance
        matches against the expressions.
        """
        # Avoid circular imports.
        from django.db.models import Value
        from django.db.models.sql import Query
        from django.db.models.sql.constants import SINGLE

        query = Query(None)
        for name, value in against.items():
            if not hasattr(value, "resolve_expression"):
                value = Value(value)
            query.add_annotation(value, name, select=False)
        query.add_annotation(Value(1), "_check")
        connection = connections[using]
        # This will raise a FieldError if a field is missing in "against".
        query.add_q(self)
        compiler = query.get_compiler(using=using)
        context_manager = (
            transaction.atomic(using=using)
            if connection.in_atomic_block
            else nullcontext()
        )
        try:
            with context_manager:
                return compiler.execute_sql(SINGLE) is not None
        except DatabaseError as e:
            logger.warning("Got a database error calling check() on %r: %s", self, e)
            return True

    def deconstruct(self):
        path = "%s.%s" % (self.__class__.__module__, self.__class__.__name__)