Introspection handler

lib/shopify_custom_data_graphql.rb

@@ -24,6 +24,46 @@ def span(span_name)
       result
     end
   end
+
+  class << self
+    def handle_introspection(query)
+      return unless query.query?
+
+      introspection_nodes = map_root_introspection_nodes(query, query.schema.query, query.selected_operation.selections)
+      return if introspection_nodes.all? { _1.nil? || _1.name == "__typename" }
+
+      errors = if introspection_nodes.any?(&:nil?)
+        introspection_nodes.reject! { _1.nil? || _1.name == "__typename" }
+        [
+          GraphQL::StaticValidation::Error.new(
+            "Cannot combine root fields with introspection fields.",
+            nodes: introspection_nodes,
+          ),
+        ]
+      end
+
+      yield(errors)
+      nil
+    end
+
+    private
+
+    def map_root_introspection_nodes(query, parent_type, selections, nodes: [])
+      selections.each do |node|
+        case node
+        when GraphQL::Language::Nodes::Field
+          field = query.get_field(parent_type, node.name)
+          nodes << (field&.introspection? ? node : nil)
+        when GraphQL::Language::Nodes::InlineFragment
+          map_root_introspection_nodes(query, parent_type, node.selections, nodes: nodes)
+        when GraphQL::Language::Nodes::FragmentSpread
+          fragment_selections = query.fragments[node.name].selections
+          map_root_introspection_nodes(query, parent_type, fragment_selections, nodes: nodes)
+        end
+      end
+      nodes
+    end
+  end
 end
 
 require_relative "shopify_custom_data_graphql/metafield_type_resolver"

lib/shopify_custom_data_graphql/client.rb

@@ -145,16 +145,22 @@ def perform_query(query_str, operation_name, tracer, &block)
       query = tracer.span("parse") do
         GraphQL::Query.new(schema, query: query_str, operation_name: operation_name)
       end
+
       errors = tracer.span("validate") do
         schema.static_validator.validate(query)[:errors]
       end
-      raise ValidationError.new(errors: errors.map(&:to_h)) if errors.any?
 
-      if introspection_query?(query)
-        result = tracer.span("introspection") { query.result.to_h }
-        return PreparedQuery::Result.new(query: query_str, tracer: tracer, result: result)
+      ShopifyCustomDataGraphQL.handle_introspection(query) do |introspection_errors|
+        if introspection_errors
+          errors.concat(introspection_errors)
+        else
+          result = tracer.span("introspection") { query.result.to_h }
+          return PreparedQuery::Result.new(query: query_str, tracer: tracer, result: result)
+        end
       end
 
+      raise ValidationError.new(errors: errors.map(&:to_h)) if errors.any?
+
       prepared_query = tracer.span("transform_request") do
         RequestTransformer.new(query).perform
       end
@@ -164,34 +170,6 @@ def perform_query(query_str, operation_name, tracer, &block)
       prepared_query.perform(tracer, &block)
     end
 
-    def introspection_query?(query)
-      return false unless query.query?
-
-      root_field_names = collect_root_field_names(query, query.selected_operation.selections)
-      return false if root_field_names.none? { INTROSPECTION_FIELDS.include?(_1) }
-
-      # hard limitation... data and introspections resolve from different places
-      unless root_field_names.all? { INTROSPECTION_FIELDS.include?(_1) }
-        raise ValidationError, "Custom data schemas cannot combine data fields with introspection fields."
-      end
-
-      true
-    end
-
-    def collect_root_field_names(query, selections, names = [])
-      selections.each do |node|
-        case node
-        when GraphQL::Language::Nodes::Field
-          names << node.name
-        when GraphQL::Language::Nodes::InlineFragment
-          collect_root_field_names(query, node.selections, names)
-        when GraphQL::Language::Nodes::FragmentSpread
-          collect_root_field_names(query, query.fragments[node.name].selections, names)
-        end
-      end
-      names
-    end
-
     def schema_file_name(handle, app_context_id = nil)
       file_name = "#{handle}_#{@admin.api_version}_cli#{@admin.api_client_id}"
       file_name << "_app#{app_context_id}" if app_context_id

test/shopify_custom_data_graphql/handle_introspection_test.rb

@@ -0,0 +1,92 @@
+# frozen_string_literal: true
+
+require "test_helper"
+
+describe "handle_introspection" do
+  def test_no_action_for_only_root_fields
+    called = false
+    query = GraphQL::Query.new(shop_schema, %|{ product }|)
+    ShopifyCustomDataGraphQL.handle_introspection(query) do
+      called = true
+    end
+
+    assert_equal false, called
+  end
+
+  def test_no_action_for_root_fields_with_typename
+    called = false
+    query = GraphQL::Query.new(shop_schema, %|{ product __typename }|)
+    ShopifyCustomDataGraphQL.handle_introspection(query) do
+      called = true
+    end
+
+    assert_equal false, called
+  end
+
+  def test_action_with_no_errors_for_only_introspection
+    called = false
+    query = GraphQL::Query.new(shop_schema, %|{ __schema }|)
+    ShopifyCustomDataGraphQL.handle_introspection(query) do |errors|
+      called = true
+      assert errors.nil?
+    end
+
+    assert called, "expected to be called"
+  end
+
+  def test_action_with_no_errors_for_introspection_and_typename
+    called = false
+    query = GraphQL::Query.new(shop_schema, %|{ __schema __typename }|)
+    ShopifyCustomDataGraphQL.handle_introspection(query) do |errors|
+      called = true
+      assert errors.nil?
+    end
+
+    assert called, "expected to be called"
+  end
+
+  def test_action_with_errors_for_introspection_and_root_field
+    called = false
+    query = GraphQL::Query.new(shop_schema, %|{ product __schema __typename }|)
+    ShopifyCustomDataGraphQL.handle_introspection(query) do |errors|
+      called = true
+      assert errors
+      assert_equal 1, errors.first.nodes.length
+      assert_equal "Cannot combine root fields with introspection fields.", errors.first.to_h["message"]
+    end
+
+    assert called, "expected to be called"
+  end
+
+  def test_action_with_errors_for_introspection_and_root_field_across_inline_fragment
+    called = false
+    query = GraphQL::Query.new(shop_schema, %|{ product ...on QueryRoot { __schema } }|)
+    ShopifyCustomDataGraphQL.handle_introspection(query) do |errors|
+      called = true
+      assert_equal 1, errors.length
+    end
+
+    assert called, "expected to be called"
+  end
+
+  def test_action_with_errors_for_introspection_and_root_field_across_fragment_spread
+    called = false
+    query = GraphQL::Query.new(shop_schema, %|{ product ...Boom } fragment Boom on QueryRoot { __schema }|)
+    ShopifyCustomDataGraphQL.handle_introspection(query) do |errors|
+      called = true
+      assert_equal 1, errors.length
+    end
+
+    assert called, "expected to be called"
+  end
+
+  def test_gracefully_ignores_invalid_field_names
+    called = false
+    query = GraphQL::Query.new(shop_schema, %|{ sfoo }|)
+    ShopifyCustomDataGraphQL.handle_introspection(query) do
+      called = true
+    end
+
+    assert_equal false, called
+  end
+end