गोलंग पर एक ग्राफिकल बैकएंड बनाएं

func main() {
  schema, err := graphql.NewSchema(defineSchema()) //      
  if err != nil {
     log.Panic("Error when creating the graphQL schema", err)
  }

  h := handler.New(&handler.Config{
     Schema:     &schema,
     Pretty:     true,
     GraphiQL:   false,
     Playground: true,
  }) //      FormatErrorFn -    

  http.Handle("/graphql", h) //      playground    
  err = http.ListenAndServe(":8080", nil)
  if err != nil {
     log.Panic("Error when starting the http server", err)
  }
}

var User = graphql.NewObject(
  graphql.ObjectConfig{
     Name: "User",
     Fields: graphql.Fields{
        "_id": &graphql.Field{
           Type: ObjectID,
        },
        "firstName": &graphql.Field{
           Type: graphql.String,
        },
        "lastName": &graphql.Field{
           Type: graphql.String,
        },
        "email": &graphql.Field{
           Type: graphql.String,
        },
     },
  },
)

var UserInput = graphql.NewInputObject(
  graphql.InputObjectConfig{
     Name: "UserInput",
     Fields: graphql.InputObjectConfigFieldMap{
        "firstName": &graphql.InputObjectFieldConfig{
           Type: graphql.String,
        },
        "lastName": &graphql.InputObjectFieldConfig{
           Type: graphql.Int,
        },
        "email": &graphql.InputObjectFieldConfig{
           Type: graphql.String,
        },
     },
  },
)

func defineSchema() graphql.SchemaConfig {
  return graphql.SchemaConfig{
     Query: graphql.NewObject(graphql.ObjectConfig{
        Name: "Query",
        Fields: graphql.Fields{
           "users": &graphql.Field{
              Name:    "users",
              Type:    graphql.NewList(User),
              Resolve: usersResolver,
           },
        },
     }),
     Mutation: graphql.NewObject(graphql.ObjectConfig{
        Name: "Mutation",
        Fields: graphql.Fields{
           "addUser": &graphql.Field{
              Name:    "addUser",
              Type:    User,
              Resolve: addUserResolver,
              Args: graphql.FieldConfigArgument{
                 "input": &graphql.ArgumentConfig{
                    Type: UserInput,
                 },
              },
           },
        },
     })}
}

type InsertOneResult struct {
  InsertedID interface{}
}

func usersCollection() *mongo.Collection { // ,   users    
  ctx, _ := context.WithTimeout(context.Background(), 10*time.Second)
  client, err := mongo.NewClient(options.Client().ApplyURI("mongodb://mongo:27017"))
  if err != nil {
     log.Panic("Error when creating mongodb connection client", err)
  }
  collection := client.Database("testing").Collection("users")
  err = client.Connect(ctx)
  if err != nil {
     log.Panic("Error when connecting to mongodb", err)
  }

  return collection
}


//      
func usersResolver(_ graphql.ResolveParams) (interface{}, error) {
  ctx, _ := context.WithTimeout(context.Background(), 10*time.Second)
  collection := usersCollection()
  result, err := collection.Find(ctx, bson.D{})
  if err != nil {
     log.Print("Error when finding user", err)
     return nil, err
  }

  defer result.Close(ctx)

  var r []bson.M
  err = result.All(ctx, &r)
  if err != nil {
     log.Print("Error when reading users from cursor", err)
  }

  return r, nil
}


//     
func addUserResolver(p graphql.ResolveParams) (interface{}, error) {
  ctx, _ := context.WithTimeout(context.Background(), 10*time.Second)
  collection := usersCollection()
  //         ,   _id
  id, err := collection.InsertOne(ctx, p.Args["input"])
  if err != nil {
     log.Print("Error when inserting user", err)
     return nil, err
  }

  var result bson.M
  //       _id
  err = collection.FindOne(ctx, bson.M{"_id": id.InsertedID}).Decode(&result)
  if err != nil {
     log.Print("Error when finding the inserted user by its id", err)
     return nil, err
  }

  return result, nil
}