Simple NestJS GraphQL API
introduction
I've had the challenge to create an GrapQL API using Spring Boot and https://github.com/graphql-java-kickstart/graphql-spring-boot in 2019 which was quit complex and tricky by the time. Therefore i wanted to try to create a simple GraphQL API using NestJS which looked a lot more mature and easy.
I was able to create the following API in about 3 hours https://github.com/sijakubo/nestjs-graphql and haven't had any big problems whatsoever.
A great feature, nestjs provides is to generate the Schema based on the defined model by just defining the following within the module.ts
GraphQLModule.forRoot<ApolloDriverConfig>({
driver: ApolloDriver,
autoSchemaFile: 'schema.gql'
}),which helps you get started pretty fast.
Query
To define a simple query you just have to create an appropriate model and resolver like e.g.:
@ObjectType()
export class Cupcake {
@Field()
id: string;
@Field()
name: string;
@Field({ nullable: true })
stock?: number;
@Field(() => [Ingredient])
ingredients: Ingredient[];
}@Resolver(() => Cupcake)
export class CupcakeResolver {
@Query(() => Cupcake)
async cupcake(@Args('id', { type: () => String }) id: string) {
return this.cupcakeRepo.data.find(value => value.id === id);
}
}This would be enough to create your first GraphQL Query to fetch cupcakes by id
Mutation
Creating mutations is already quit simple.
Define the following to create the first mutation:
@InputType()
export class CreateCupcakeResource {
@Field({ nullable: false })
name: string;
@Field({ nullable: true })
stock?: number;
@Field(() => [CreateIngredientResource])
ingredients: Array<CreateIngredientResource>;
}@InputType()
export class CreateIngredientResource {
@Field({ nullable: false })
name: string;
}@Resolver(() => Cupcake)
export class CupcakeResolver {
@Mutation(() => Cupcake)
async createCupcake(@Args('cupcake') cupcake: CreateCupcakeResource) {
...
return createdCupcake;
}
}Subscriptions
A great way do distribute information in a 'real time' manner is by using subscriptions which is also quit easy to accomplish using NestJS. Here a client can subscribe to some sort of topic and will be informed when new informations are available
Add the transmission protocol to your module.ts (subscriptions-transport-ws or graphql-ws)
GraphQLModule.forRoot<ApolloDriverConfig>({
...
subscriptions: {
'subscriptions-transport-ws': true
},
}),define the topic on which the information will be published and push your information to the topic
const pubSub = new PubSub();
@Resolver(() => Rating)
export class RatingResolver {
private readonly topicRatingAdded = 'ratingAdded';
@Subscription(() => Rating)
async ratingAdded() {
return pubSub.asyncIterator(this.topicRatingAdded);
}
@Mutation(() => Rating)
async createRating(@Args('rating') rating: CreateRatingResource) {
...
await pubSub.publish(this.topicRatingAdded, { ratingAdded: createdRating });
...
}see also:
Standort Hannover
newcubator GmbH
Bödekerstraße 22
30161 Hannover
Standort Dortmund
newcubator GmbH
Westenhellweg 85-89
44137 Dortmund