Handle missing variables like a validation error in query analysis

Author: rmosolgo

lib/graphql/query.rb

@@ -73,7 +73,10 @@ def result
     # If more than one operation is present, it must be named at runtime.
     # @return [GraphQL::Language::Nodes::OperationDefinition, nil]
     def selected_operation
-      @selected_operation ||= find_operation(@operations, @operation_name)
+      @selected_operation ||= begin
+        perform_validation
+        @selected_operation
+      end
     end
 
     # Determine the values for variables of this query, using default values
@@ -118,9 +121,18 @@ def arguments_for(irep_node, definition)
     private
 
     def perform_validation
+      @selected_operation = find_operation(@operations, @operation_name)
       validation_result = schema.static_validator.validate(self)
       @validation_errors = validation_result[:errors]
       @internal_representation = validation_result[:irep]
+      if @validation_errors.none?
+        # Accessing variables will raise errors if there are any :S
+        variables
+      end
+      nil
+    rescue GraphQL::Query::OperationNameMissingError, GraphQL::Query::VariableValidationError => err
+      @validation_errors = [err.to_h]
+      @internal_representation = nil
       nil
     end
 

spec/graphql/analysis/analyze_query_spec.rb

@@ -26,7 +26,8 @@ def call(memo, visit_type, irep_node)
     let(:type_collector) { TypeCollector.new }
     let(:analyzers) { [type_collector, node_counter] }
     let(:reduce_result) { GraphQL::Analysis.analyze_query(query, analyzers) }
-    let(:query) { GraphQL::Query.new(DummySchema, query_string) }
+    let(:variables) { {} }
+    let(:query) { GraphQL::Query.new(DummySchema, query_string, variables: variables) }
     let(:query_string) {%|
       {
         cheese(id: 1) {
@@ -46,5 +47,33 @@ def call(memo, visit_type, irep_node)
       }
       assert_equal expected_node_counts, node_counts
     end
+
+    describe "when a variable is missing" do
+      let(:query_string) {%|
+        query something($cheeseId: Int!){
+          cheese(id: $cheeseId) {
+            id
+            flavor
+          }
+        }
+      |}
+      let(:variable_accessor) { -> (memo, visit_type, irep_node) { query.variables["cheeseId"] } }
+
+      before do
+        @previous_query_analyzers = DummySchema.query_analyzers.dup
+        DummySchema.query_analyzers.clear
+        DummySchema.query_analyzers << variable_accessor
+      end
+
+      after do
+        DummySchema.query_analyzers.clear
+        DummySchema.query_analyzers.push(*@previous_query_analyzers)
+      end
+
+      it "returns an error" do
+        error = query.result["errors"].first
+        assert_equal "Variable cheeseId of type Int! was provided invalid value", error["message"]
+      end
+    end
   end
 end