Modify Context

main.go

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}]}}}