Remove new types from IM cache on generate error

Previously they would hang around until database restart - corrupting the schema and preventing schema correction

query/graphql/schema/generate.go

@@ -71,9 +71,36 @@ func (g *Generator) FromSDL(schema string) ([]*gql.Object, *ast.Document, error)
 	return types, doc, err
 }
 
+func (g *Generator) FromAST(document *ast.Document) ([]*gql.Object, error) {
+	typeMapBeforeMutation := g.manager.schema.TypeMap()
+	typesBeforeMutation := make(map[string]interface{}, len(typeMapBeforeMutation))
+
+	for typeName := range typeMapBeforeMutation {
+		typesBeforeMutation[typeName] = struct{}{}
+	}
+
+	result, err := g.fromAST(document)
+
+	if err != nil {
+		// If there is an error we should drop any new objects as they may be partial, poluting the in memory cache
+		// This is quite a simple check at the moment (on type name) - this should be expanded when we allow schema mutation/deletion
+		// There is no guarantee that `typeMapBeforeMutation` will still be the object returned by `schema.TypeMap()`, so we should re-fetch it
+		typeMapAfterMutation := g.manager.schema.TypeMap()
+		for typeName := range typeMapAfterMutation {
+			if _, typeExistedBeforeMutation := typesBeforeMutation[typeName]; !typeExistedBeforeMutation {
+				delete(typeMapAfterMutation, typeName)
+			}
+		}
+
+		return nil, err
+	}
+
+	return result, nil
+}
+
 // FromAST generates the query type definitions from a
 // parsed GraphQL Schema Definition Language AST document
-func (g *Generator) FromAST(document *ast.Document) ([]*gql.Object, error) {
+func (g *Generator) fromAST(document *ast.Document) ([]*gql.Object, error) {
 	// build base types
 	defs, err := g.buildTypesFromAST(document)
 	if err != nil {

query/graphql/schema/generate_test.go

@@ -74,6 +74,23 @@ func Test_Generator_buildTypesFromAST_SingleScalarField(t *testing.T) {
 		}, "")
 }
 
+func Test_Generator_CleansUpInvalidTypes_GivenInvalidFieldType(t *testing.T) {
+	g := newTestGenerator()
+
+	runTestConfigForbuildTypesFromASTSuite(t, g,
+		`
+		type MyObject {
+			myField: string,
+			myOtherField: String
+		}
+		`,
+		[]*gql.Object{},
+		"No type found for given name: string")
+
+	_, exists := g.manager.schema.TypeMap()["MyObject"]
+	assert.False(t, exists, "Invalid object was not cleaned from type map")
+}
+
 func Test_Generator_buildTypesFromAST_SingleNonNullScalarField(t *testing.T) {
 	g := newTestGenerator()