examples: adds simple example for concurrent-resolvers

Author: chris-ramon

examples/concurrent-resolvers/main.go

@@ -0,0 +1,108 @@
+package main
+
+import (
+	"encoding/json"
+	"fmt"
+	"log"
+
+	"github.com/graphql-go/graphql"
+)
+
+type Foo struct {
+	Name string
+}
+
+var FieldFooType = graphql.NewObject(graphql.ObjectConfig{
+	Name: "Foo",
+	Fields: graphql.Fields{
+		"name": &graphql.Field{Type: graphql.String},
+	},
+})
+
+type Bar struct {
+	Name string
+}
+
+var FieldBarType = graphql.NewObject(graphql.ObjectConfig{
+	Name: "Bar",
+	Fields: graphql.Fields{
+		"name": &graphql.Field{Type: graphql.String},
+	},
+})
+
+// QueryType fields: `concurrentFieldFoo` and `concurrentFieldBar` are resolved
+// concurrently because they belong to the same field-level and their `Resolve`
+// function returns a function (thunk).
+var QueryType = graphql.NewObject(graphql.ObjectConfig{
+	Name: "Query",
+	Fields: graphql.Fields{
+		"concurrentFieldFoo": &graphql.Field{
+			Type: FieldFooType,
+			Resolve: func(p graphql.ResolveParams) (interface{}, error) {
+				var foo = Foo{Name: "Foo's name"}
+				return func() (interface{}, error) {
+					return &foo, nil
+				}, nil
+			},
+		},
+		"concurrentFieldBar": &graphql.Field{
+			Type: FieldBarType,
+			Resolve: func(p graphql.ResolveParams) (interface{}, error) {
+				type result struct {
+					data interface{}
+					err  error
+				}
+				ch := make(chan *result, 1)
+				go func() {
+					defer close(ch)
+					bar := &Bar{Name: "Bar's name"}
+					ch <- &result{data: bar, err: nil}
+				}()
+				return func() (interface{}, error) {
+					r := <-ch
+					return r.data, r.err
+				}, nil
+			},
+		},
+	},
+})
+
+func main() {
+	schema, err := graphql.NewSchema(graphql.SchemaConfig{
+		Query: QueryType,
+	})
+	if err != nil {
+		log.Fatal(err)
+	}
+	query := `
+		query {
+			concurrentFieldFoo {
+				name
+			}
+			concurrentFieldBar {
+				name
+			}
+		}
+	`
+	result := graphql.Do(graphql.Params{
+		RequestString: query,
+		Schema:        schema,
+	})
+	b, err := json.Marshal(result)
+	if err != nil {
+		log.Fatal(err)
+	}
+	fmt.Printf("%s", b)
+	/*
+		{
+		  "data": {
+		    "concurrentFieldBar": {
+		      "name": "Bar's name"
+		    },
+		    "concurrentFieldFoo": {
+		      "name": "Foo's name"
+		    }
+		  }
+		}
+	*/
+}