Python lookups.Lookup方法代码示例

# 需要导入模块: from django.db.models import lookups [as 别名]
# 或者: from django.db.models.lookups import Lookup [as 别名]
def _process_filter(self, field_attname, lookup, value, check_only=False):
        # Get the field
        field = self._get_filterable_field(field_attname)

        if field is None:
            raise FilterFieldError(
                'Cannot filter search results with field "' + field_attname + '". Please add index.FilterField(\''
                + field_attname + '\') to ' + self.queryset.model.__name__ + '.search_fields.',
                field_name=field_attname
            )

        # Process the lookup
        if not check_only:
            result = self._process_lookup(field, lookup, value)

        if result is None:
            raise FilterError(
                'Could not apply filter on search results: "' + field_attname + '__'
                + lookup + ' = ' + str(value) + '". Lookup "' + lookup + '"" not recognised.'
            )

        return result 

# 需要导入模块: from django.db.models import lookups [as 别名]
# 或者: from django.db.models.lookups import Lookup [as 别名]
def get_lookup(self, lookup_name):
        from django.db.models.lookups import Lookup
        found = self._get_lookup(lookup_name)
        if found is None and hasattr(self, 'output_field'):
            return self.output_field.get_lookup(lookup_name)
        if found is not None and not issubclass(found, Lookup):
            return None
        return found 

# 需要导入模块: from django.db.models import lookups [as 别名]
# 或者: from django.db.models.lookups import Lookup [as 别名]
def _get_filters_from_where_node(self, where_node, check_only=False):
        # Check if this is a leaf node
        if isinstance(where_node, Lookup):
            field_attname = where_node.lhs.target.attname
            lookup = where_node.lookup_name
            value = where_node.rhs

            # Ignore pointer fields that show up in specific page type queries
            if field_attname.endswith('_ptr_id'):
                return

            # Process the filter
            return self._process_filter(field_attname, lookup, value, check_only=check_only)

        elif isinstance(where_node, SubqueryConstraint):
            raise FilterError('Could not apply filter on search results: Subqueries are not allowed.')

        elif isinstance(where_node, WhereNode):
            # Get child filters
            connector = where_node.connector
            child_filters = [self._get_filters_from_where_node(child) for child in where_node.children]

            if not check_only:
                child_filters = [child_filter for child_filter in child_filters if child_filter]
                return self._connect_filters(child_filters, connector, where_node.negated)

        else:
            raise FilterError('Could not apply filter on search results: Unknown where node: ' + str(type(where_node))) 

# 需要导入模块: from django.db.models import lookups [as 别名]
# 或者: from django.db.models.lookups import Lookup [as 别名]
def rewrite_cols(self, annotation, col_cnt):
        # We must make sure the inner query has the referred columns in it.
        # If we are aggregating over an annotation, then Django uses Ref()
        # instances to note this. However, if we are annotating over a column
        # of a related model, then it might be that column isn't part of the
        # SELECT clause of the inner query, and we must manually make sure
        # the column is selected. An example case is:
        #    .aggregate(Sum('author__awards'))
        # Resolving this expression results in a join to author, but there
        # is no guarantee the awards column of author is in the select clause
        # of the query. Thus we must manually add the column to the inner
        # query.
        orig_exprs = annotation.get_source_expressions()
        new_exprs = []
        for expr in orig_exprs:
            # FIXME: These conditions are fairly arbitrary. Identify a better
            # method of having expressions decide which code path they should
            # take.
            if isinstance(expr, Ref):
                # Its already a Ref to subquery (see resolve_ref() for
                # details)
                new_exprs.append(expr)
            elif isinstance(expr, (WhereNode, Lookup)):
                # Decompose the subexpressions further. The code here is
                # copied from the else clause, but this condition must appear
                # before the contains_aggregate/is_summary condition below.
                new_expr, col_cnt = self.rewrite_cols(expr, col_cnt)
                new_exprs.append(new_expr)
            elif isinstance(expr, Col) or (expr.contains_aggregate and not expr.is_summary):
                # Reference to column. Make sure the referenced column
                # is selected.
                col_cnt += 1
                col_alias = '__col%d' % col_cnt
                self.annotations[col_alias] = expr
                self.append_annotation_mask([col_alias])
                new_exprs.append(Ref(col_alias, expr))
            else:
                # Some other expression not referencing database values
                # directly. Its subexpression might contain Cols.
                new_expr, col_cnt = self.rewrite_cols(expr, col_cnt)
                new_exprs.append(new_expr)
        annotation.set_source_expressions(new_exprs)
        return annotation, col_cnt