Merge pull request #5375 from rmosolgo/improve-scalar-coercion-result-errors

Improve scalar result coercion execution errors

Author: rmosolgo

lib/graphql/execution/interpreter/runtime.rb

@@ -675,6 +675,8 @@ def continue_field(value, owner_type, field, current_type, ast_node, next_select
           when "SCALAR", "ENUM"
             r = begin
               current_type.coerce_result(value, context)
+            rescue GraphQL::ExecutionError => ex_err
+              return continue_value(ex_err, field, is_non_null, ast_node, result_name, selection_result)
             rescue StandardError => err
               query.handle_or_reraise(err)
             end

spec/graphql/schema/scalar_spec.rb

@@ -119,18 +119,28 @@ class CustomScalar < GraphQL::Schema::Scalar
         def self.coerce_input(val, ctx)
           raise GraphQL::CoercionError, "#{val.inspect} can't be Custom value"
         end
+
+        def self.coerce_result(val, ctx)
+          raise GraphQL::CoercionError, "#{val.inspect} can't be Custom value"
+        end
       end
 
       class Query < GraphQL::Schema::Object
         field :f1, String do
           argument :arg, CustomScalar
         end
+
+        field :f2, CustomScalar
+
+        def f2
+          "bad"
+        end
       end
 
       query(Query)
     end
 
-    it "makes a nice validation error" do
+    it "makes a nice validation error for input coercion" do
       result = CoercionErrorSchema.execute("{ f1(arg: \"a\") }")
       expected_error = {
         "message" => "\"a\" can't be Custom value",
@@ -143,8 +153,17 @@ class Query < GraphQL::Schema::Object
       }
       assert_equal [expected_error], result["errors"]
     end
-  end
 
+    it "makes a nice validation error for reuslt coercion" do
+      result = CoercionErrorSchema.execute("{ f2 }")
+      expected_error = {
+        "message" => "\"bad\" can't be Custom value",
+        "locations" => [{"line"=>1, "column"=>3}],
+        "path" => ["f2"],
+      }
+      assert_equal [expected_error], result["errors"]
+    end
+  end
 
   describe "validate_input with good input" do
     let(:result) { GraphQL::Types::Int.validate_input(150, GraphQL::Query::NullContext.instance) }