Subscriptions

Subscription type definitions are similar to the type definitions of regular objects. However, instead of having a Resolver{FieldName} method as a resolver, you have a Subscribe{FieldName} method that returns a receive only channel of the result type.

You can define arguments for a subscription field similar to how you would for a regular field resolver as discussed here.

Example with Timer

package main
import (    "time"
    "github.com/shreyas44/groot"    "github.com/shreya44/handler")
type Query struct {    Hello string `json:"hello"`}
func (q Query) ResolveHello() (string, error) {    return "Hello World", nil}
type Notification struct {    Time int `json:"time"`}
type Subscription struct {    Notification Notification `json:"notification"`}
func (s Subscription) SubscribeNotification(ctx context.Context) (<-chan Notification, error) {    ch := make(chan Notification)    ticker := time.NewTicker(time.Second)
    go func() {        for {            select {            case <-ctx.Done():                ticker.Stop()                return            case <-ticker.C:                ch <- Notification{                    Time: int(time.Now().Unix()),                }            }        }    }()
    return ch, nil}
func main() {    schema, err := groot.NewSchema(groot.SchemaConfig{        Query:        groot.MustParseObject(Query{}),        Subscription: groot.MustParseObject(Subscription{}),    })
    if err != nil {        panic(err)    }
    h := handler.New(&handler.Config{        Schema:     &schema,        Pretty:     true,        GraphiQL:   false,        Playground: true,    })
    subscriptionHandler := handler.NewSubscriptionHandler(&schema)
    http.Handle("/graphql", h)    http.Handle("/subscriptions", subscriptionHandler)    log.Fatal(http.ListenAndServe(":8080", nil))}

The github.com/shreyas44/handler is a fork of the github.com/graphql-go/handler package with an additional NewSubscriptionHandler function to handle subscriptions.