Merge 7ced578 into fc25dbd

examples/modify-context/main.go

@@ -0,0 +1,75 @@
+package main
+
+import (
+	"context"
+	"encoding/json"
+	"fmt"
+	"log"
+
+	"github.com/graphql-go/graphql"
+)
+
+type User struct {
+	ID int `json:"id"`
+}
+
+var UserType = graphql.NewObject(graphql.ObjectConfig{
+	Name: "User",
+	Fields: graphql.Fields{
+		"id": &graphql.Field{
+			Type: graphql.Int,
+			Resolve: func(p graphql.ResolveParams) (interface{}, error) {
+				rootValue := p.Info.RootValue.(map[string]interface{})
+				if rootValue["data-from-parent"] == "ok" &&
+					rootValue["data-before-execution"] == "ok" {
+					user := p.Source.(User)
+					return user.ID, nil
+				}
+				return nil, nil
+			},
+		},
+	},
+})
+
+func main() {
+	schema, err := graphql.NewSchema(graphql.SchemaConfig{
+		Query: graphql.NewObject(graphql.ObjectConfig{
+			Name: "Query",
+			Fields: graphql.Fields{
+				"users": &graphql.Field{
+					Type: graphql.NewList(UserType),
+					Resolve: func(p graphql.ResolveParams) (interface{}, error) {
+						rootValue := p.Info.RootValue.(map[string]interface{})
+						rootValue["data-from-parent"] = "ok"
+						result := []User{
+							User{ID: 1},
+						}
+						return result, nil
+
+					},
+				},
+			},
+		}),
+	})
+	if err != nil {
+		log.Fatal(err)
+	}
+	ctx := context.WithValue(context.Background(), "currentUser", User{ID: 100})
+	// Instead of trying to modify context within a resolve function, use:
+	// `graphql.Params.RootObject` is a mutable optional variable and available on
+	// each resolve function via: `graphql.ResolveParams.Info.RootValue`.
+	rootObject := map[string]interface{}{
+		"data-before-execution": "ok",
+	}
+	result := graphql.Do(graphql.Params{
+		Context:       ctx,
+		RequestString: "{ users { id } }",
+		RootObject:    rootObject,
+		Schema:        schema,
+	})
+	b, err := json.Marshal(result)
+	if err != nil {
+		log.Fatal(err)
+	}
+	fmt.Printf("%s\n", string(b)) // {"data":{"users":[{"id":1}]}}
+}