Adding node_tree method in utilities to debug and compare DocumentNode instances (#449)

DSL: Set variable_definitions to None for Fragments by default instead of empty tuple

Author: leszekhanusz

gql/dsl.py

@@ -1068,10 +1068,26 @@ def executable_ast(self) -> FragmentDefinitionNode:
                 "Missing type condition. Please use .on(type_condition) method"
             )
 
+        fragment_variable_definitions = self.variable_definitions.get_ast_definitions()
+
+        if len(fragment_variable_definitions) == 0:
+            """Fragment variable definitions are obsolete and only supported on
+            graphql-core if the Parser is initialized with:
+            allow_legacy_fragment_variables=True.
+
+            We will not provide variable_definitions instead of providing an empty
+            tuple to be coherent with how it works by default on graphql-core.
+            """
+            variable_definition_kwargs = {}
+        else:
+            variable_definition_kwargs = {
+                "variable_definitions": fragment_variable_definitions
+            }
+
         return FragmentDefinitionNode(
             type_condition=NamedTypeNode(name=NameNode(value=self._type.name)),
             selection_set=self.selection_set,
-            variable_definitions=self.variable_definitions.get_ast_definitions(),
+            **variable_definition_kwargs,
             name=NameNode(value=self.name),
             directives=(),
         )

gql/utilities/__init__.py

@@ -1,12 +1,14 @@
 from .build_client_schema import build_client_schema
 from .get_introspection_query_ast import get_introspection_query_ast
+from .node_tree import node_tree
 from .parse_result import parse_result
 from .serialize_variable_values import serialize_value, serialize_variable_values
 from .update_schema_enum import update_schema_enum
 from .update_schema_scalars import update_schema_scalar, update_schema_scalars
 
 __all__ = [
     "build_client_schema",
+    "node_tree",
     "parse_result",
     "get_introspection_query_ast",
     "serialize_variable_values",

gql/utilities/node_tree.py

@@ -0,0 +1,89 @@
+from typing import Any, Iterable, List, Optional, Sized
+
+from graphql import Node
+
+
+def _node_tree_recursive(
+    obj: Any,
+    *,
+    indent: int = 0,
+    ignored_keys: List,
+):
+
+    assert ignored_keys is not None
+
+    results = []
+
+    if hasattr(obj, "__slots__"):
+
+        results.append("  " * indent + f"{type(obj).__name__}")
+
+        try:
+            keys = obj.keys
+        except AttributeError:
+            # If the object has no keys attribute, print its repr and return.
+            results.append("  " * (indent + 1) + repr(obj))
+        else:
+            for key in keys:
+                if key in ignored_keys:
+                    continue
+                attr_value = getattr(obj, key, None)
+                results.append("  " * (indent + 1) + f"{key}:")
+                if isinstance(attr_value, Iterable) and not isinstance(
+                    attr_value, (str, bytes)
+                ):
+                    if isinstance(attr_value, Sized) and len(attr_value) == 0:
+                        results.append(
+                            "  " * (indent + 2) + f"empty {type(attr_value).__name__}"
+                        )
+                    else:
+                        for item in attr_value:
+                            results.append(
+                                _node_tree_recursive(
+                                    item,
+                                    indent=indent + 2,
+                                    ignored_keys=ignored_keys,
+                                )
+                            )
+                else:
+                    results.append(
+                        _node_tree_recursive(
+                            attr_value,
+                            indent=indent + 2,
+                            ignored_keys=ignored_keys,
+                        )
+                    )
+    else:
+        results.append("  " * indent + repr(obj))
+
+    return "\n".join(results)
+
+
+def node_tree(
+    obj: Node,
+    *,
+    ignore_loc: bool = True,
+    ignore_block: bool = True,
+    ignored_keys: Optional[List] = None,
+):
+    """Method which returns a tree of Node elements as a String.
+
+    Useful to debug deep DocumentNode instances created by gql or dsl_gql.
+
+    WARNING: the output of this method is not guaranteed and may change without notice.
+    """
+
+    assert isinstance(obj, Node)
+
+    if ignored_keys is None:
+        ignored_keys = []
+
+    if ignore_loc:
+        # We are ignoring loc attributes by default
+        ignored_keys.append("loc")
+
+    if ignore_block:
+        # We are ignoring block attributes by default (in StringValueNode)
+        ignored_keys.append("block")
+
+    return _node_tree_recursive(obj, ignored_keys=ignored_keys)

tests/regressions/issue_447_dsl_missing_directives/test_dsl_directives.py

@@ -1,5 +1,6 @@
-from gql import Client
-from gql.dsl import DSLFragment, DSLQuery, DSLSchema, dsl_gql
+from gql import Client, gql
+from gql.dsl import DSLFragment, DSLQuery, DSLSchema, dsl_gql, print_ast
+from gql.utilities import node_tree
 
 schema_str = """
 type MonsterForm {
@@ -57,3 +58,17 @@ def test_issue_447():
     q = dsl_gql(sprite, copy_of, DSLQuery(query))
 
     client.validate(q)
+
+    # Creating a tree from the DocumentNode created by dsl_gql
+    dsl_tree = node_tree(q)
+
+    # Creating a tree from the DocumentNode created by gql
+    gql_tree = node_tree(gql(print_ast(q)))
+
+    print("=======")
+    print(dsl_tree)
+    print("+++++++")
+    print(gql_tree)
+    print("=======")
+
+    assert dsl_tree == gql_tree