support defaultValue for input types

examples/simple-usage/recipe-resolver.ts

@@ -44,7 +44,7 @@ export class RecipeResolver implements ResolverInterface<Recipe> {
   @FieldResolver()
   ratingsCount(
     @Root() recipe: Recipe,
-    @Arg("minRate", type => Int, { nullable: true }) minRate: number = 0.0,
+    @Arg("minRate", type => Int, { nullable: true, defaultValue: 0.0 }) minRate: number,
   ): number {
     return recipe.ratings.filter(rating => rating >= minRate).length;
   }

examples/simple-usage/schema.gql

@@ -26,7 +26,7 @@ type Recipe {
   description: String
   ratings: [Int!]!
   creationDate: DateTime!
-  ratingsCount(minRate: Int): Int!
+  ratingsCount(minRate: Int = 0): Int!
   averageRating: Float
 }
 

src/decorators/types.ts

@@ -21,6 +21,7 @@ export type SubscriptionTopicFunc = (
 
 export interface DecoratorTypeOptions {
   nullable?: boolean;
+  defaultValue?: any;
 }
 export interface TypeOptions extends DecoratorTypeOptions {
   array?: boolean;

src/helpers/types.ts

@@ -44,7 +44,7 @@ export function wrapWithTypeOptions<T extends GraphQLType>(
   if (typeOptions.array) {
     gqlType = new GraphQLList(new GraphQLNonNull(gqlType));
   }
-  if (!typeOptions.nullable) {
+  if (!typeOptions.nullable && typeOptions.defaultValue === undefined) {
     gqlType = new GraphQLNonNull(gqlType);
   }
   return gqlType as T;

src/schema/schema-generator.ts

@@ -287,6 +287,7 @@ export abstract class SchemaGenerator {
                 fieldsMap[field.schemaName] = {
                   description: field.description,
                   type: this.getGraphQLInputType(field.name, field.getType(), field.typeOptions),
+                  defaultValue: field.typeOptions.defaultValue,
                 };
                 return fieldsMap;
               },
@@ -410,6 +411,7 @@ export abstract class SchemaGenerator {
         args[param.name] = {
           description: param.description,
           type: this.getGraphQLInputType(param.name, param.getType(), param.typeOptions),
+          defaultValue: param.typeOptions.defaultValue,
         };
       } else if (param.kind === "args") {
         const argumentType = getMetadataStorage().argumentTypes.find(
@@ -437,6 +439,7 @@ export abstract class SchemaGenerator {
       args[field.schemaName] = {
         description: field.description,
         type: this.getGraphQLInputType(field.name, field.getType(), field.typeOptions),
+        defaultValue: field.typeOptions.defaultValue,
       };
     });
   }

tests/functional/resolvers.ts

@@ -104,6 +104,7 @@ describe("Resolvers", () => {
           @Arg("stringArrayArg", type => String) stringArrayArg: string[],
           @Arg("explicitArrayArg", type => [String]) explicitArrayArg: any,
           @Arg("nullableStringArg", { nullable: true }) nullableStringArg?: string,
+          @Arg("defaultStringArg", { defaultValue: "bob" }) defaultStringArg?: string,
         ): any {
           return "argMethodField";
         }
@@ -270,7 +271,7 @@ describe("Resolvers", () => {
         const argMethodFieldInnerType = argMethodFieldType.ofType as IntrospectionNamedTypeRef;
 
         expect(argMethodField.name).toEqual("argMethodField");
-        expect(argMethodField.args).toHaveLength(8);
+        expect(argMethodField.args).toHaveLength(9);
         expect(argMethodFieldType.kind).toEqual(TypeKind.NON_NULL);
         expect(argMethodFieldInnerType.kind).toEqual(TypeKind.SCALAR);
         expect(argMethodFieldInnerType.name).toEqual("String");
@@ -375,6 +376,15 @@ describe("Resolvers", () => {
         expect(inputArgInnerType.kind).toEqual(TypeKind.INPUT_OBJECT);
         expect(inputArgInnerType.name).toEqual("SampleInput");
       });
+
+      it("should generate nullable string arg type with defaultValue for object field method", async () => {
+        const inputArg = argMethodField.args.find(arg => arg.name === "defaultStringArg")!;
+        const nullableDefaultValueStringArgType = inputArg.type as IntrospectionNamedTypeRef;
+
+        expect(inputArg.defaultValue).toBe('"bob"');
+        expect(nullableDefaultValueStringArgType.kind).toEqual(TypeKind.SCALAR);
+        expect(nullableDefaultValueStringArgType.name).toEqual("String");
+      });
     });
 
     describe("Args object", () => {