docs: query analysis use case (#17766)

Co-authored-by: Harrison Chase <hw.chase.17@gmail.com>

libs/langchain/langchain/chains/query_constructor/base.py

@@ -137,15 +137,18 @@ def fix_filter_directive(
         if allowed_operators and filter.operator not in allowed_operators:
             return None
         args = [
-            fix_filter_directive(
-                arg,
-                allowed_comparators=allowed_comparators,
-                allowed_operators=allowed_operators,
-                allowed_attributes=allowed_attributes,
+            cast(
+                FilterDirective,
+                fix_filter_directive(
+                    arg,
+                    allowed_comparators=allowed_comparators,
+                    allowed_operators=allowed_operators,
+                    allowed_attributes=allowed_attributes,
+                ),
             )
             for arg in filter.arguments
+            if arg is not None
         ]
-        args = [arg for arg in args if arg is not None]
         if not args:
             return None
         elif len(args) == 1 and filter.operator in (Operator.AND, Operator.OR):

libs/langchain/langchain/chains/query_constructor/ir.py

@@ -103,6 +103,13 @@ class Comparison(FilterDirective):
     attribute: str
     value: Any
 
+    def __init__(
+        self, comparator: Comparator, attribute: str, value: Any, **kwargs: Any
+    ) -> None:
+        super().__init__(
+            comparator=comparator, attribute=attribute, value=value, **kwargs
+        )
+
 
 class Operation(FilterDirective):
     """A logical operation over other directives."""
@@ -110,6 +117,11 @@ class Operation(FilterDirective):
     operator: Operator
     arguments: List[FilterDirective]
 
+    def __init__(
+        self, operator: Operator, arguments: List[FilterDirective], **kwargs: Any
+    ):
+        super().__init__(operator=operator, arguments=arguments, **kwargs)
+
 
 class StructuredQuery(Expr):
     """A structured query."""
@@ -120,3 +132,12 @@ class StructuredQuery(Expr):
     """Filtering expression."""
     limit: Optional[int]
     """Limit on the number of results."""
+
+    def __init__(
+        self,
+        query: str,
+        filter: Optional[FilterDirective],
+        limit: Optional[int] = None,
+        **kwargs: Any,
+    ):
+        super().__init__(query=query, filter=filter, limit=limit, **kwargs)

libs/langchain/langchain/retrievers/self_query/supabase.py

@@ -68,14 +68,14 @@ class SupabaseVectorTranslator(Visitor):
             return self.visit_operation(
                 Operation(
                     operator=Operator.AND,
-                    arguments=(
+                    arguments=[
                         Comparison(
                             comparator=comparison.comparator,
                             attribute=comparison.attribute,
                             value=value,
                         )
                         for value in comparison.value
-                    ),
+                    ],
                 )
             )