Why graphql

What is GraphQL?

GraphQL is a query language for APIs and a runtime for fulfilling those queries with your existing data. GraphQL provides a complete and understandable description of the data in your API, gives clients the power to ask for exactly what they need and nothing more, makes it easier to evolve APIs over time, and enables powerful developer tools.

Why use GraphQL?

I often encounter such a situation …

“Hey , Hu bro there is xx field missing in your xx api…”

“Hey, there is too many field in your api, i just need xx and xx field, please modify it…”

“Hey, i have to request three api in this page, would you please combine those in one API?…”

“Em…..”

“Hey, Hu bro the Api doc has not been updated…What paramater do i need to pass?”

What i want to say is the above problem solved by GraphQL.

What is apollo Graphql?

GraphQL is just a query language. And in order to use it easily, we need to use a platform that will do all the heavy lifting for us. One such platform is provided by Apollo.

Main process?

Describe your data

type Project {
  name: String
  tagline: String
  contributors: [User]
}

Ask for what u What

{
  project(name: "GraphQL") {
    tagline
  }
}

Get predictable results

{
  "project": {
    "tagline": "A query language for APIs"
  }
}

How to use?

  1. Build a schema

    const userSchema = gql`
        type Query {
            getUser(id: ID): User
            getUsers: [User]
        }

        type Mutation {
            createUser(userInfo: CreateUserInput): User
        }
        
        input CreateUserInput {
            name: String
            age: Int
            address: String
        }
        
        type User {
            id: ID
            name: String
            age: Int
            address: String
            number: String
        }
    `;

  2. Write query resolvers

    Briefly, Query for get request, Mutation for update request.

    const userResolvers = {
        Query: {
            getUser: async (parent, args, context, info) => await userLoader.getUser(args.id),
            getUsers: async (parent, args, context, info) => await userLoader.getUsers()
        },
        Mutation: {
            createUser: async (_, args, { dataSources }) => {
                return await userLoader.createUser(args.userInfo)
            }
        }
    };

  3. Intergrating with your node middleare

    const apolloServer = new ApolloServer({
        typeDefs: schema,
        resolvers,
    });
    apolloServer.applyMiddleware({ app: app, path: '/graphql' });
    const port = process.env.PORT || 3333
    const server = app.listen(port, () => console.info(`Listening to http://localhost:${port}/graphql 🚀`));

The entire code can be viewed here

Q&A

How to Modularizing your GraphQL?)

Error Handling

Security

Intergration testing