examples_test.go

package graphql_test

import (
	"context"
	"encoding/json"
	"fmt"
	"os"
	"strings"
	"text/template"

	"github.com/graph-gophers/graphql-go"
	"github.com/graph-gophers/graphql-go/example/starwars"
)

type Resolver struct {
	post *Post
}

func (r *Resolver) Post() *Post {
	return r.post
}

type Post struct {
	id    graphql.ID
	title string
}

func (p *Post) ID() graphql.ID {
	return p.id
}

func (p *Post) Title() string {
	return p.title
}

func ExampleID() {
	schemaString := `
		schema {
			query: Query
		}

		type Query {
			post: Post!
		}

		type Post {
			id: ID!
			title: String!
		}
	`

	resolver := &Resolver{
		post: &Post{
			id:    graphql.ID("5"),
			title: "title",
		},
	}

	schema := graphql.MustParseSchema(schemaString, resolver)

	query := `
		query {
			post {
				id
				title
			}
		}
	`

	res := schema.Exec(context.Background(), query, "", nil)

	enc := json.NewEncoder(os.Stdout)
	enc.SetIndent("", "  ")
	err := enc.Encode(res)
	if err != nil {
		panic(err)
	}
	// output:
	// {
	//   "data": {
	//     "post": {
	//       "id": "5",
	//       "title": "title"
	//     }
	//   }
	// }
}

func ExampleMaxDepth() {
	schema := graphql.MustParseSchema(starwars.Schema, &starwars.Resolver{}, graphql.MaxDepth(3))

	// this query has a depth of 4
	query := `
	  query {
	    hero(episode:EMPIRE) { # level 1
	      name                 # level 2
	      friends { 
	        name               # level 3
	        friends { 
	          id               # level 4 - this would exceed the max depth
	        }
	      }
	    }
	  }`

	res := schema.Exec(context.Background(), query, "", nil)

	enc := json.NewEncoder(os.Stdout)
	enc.SetIndent("", "  ")
	err := enc.Encode(res)
	if err != nil {
		panic(err)
	}
	// output:
	// {
	//   "errors": [
	//     {
	//       "message": "Field \"id\" has depth 4 that exceeds max depth 3",
	//       "locations": [
	//         {
	//           "line": 8,
	//           "column": 12
	//         }
	//       ]
	//     }
	//   ]
	// }
}

func ExampleMaxQueryLength() {
	schema := graphql.MustParseSchema(starwars.Schema, &starwars.Resolver{}, graphql.MaxQueryLength(50))

	// this query has a length of 53
	query := `{
	  hero(episode:EMPIRE) {
	    id
	    name
	  }
	}`

	res := schema.Exec(context.Background(), query, "", nil)

	enc := json.NewEncoder(os.Stdout)
	enc.SetIndent("", "  ")
	err := enc.Encode(res)
	if err != nil {
		panic(err)
	}
	// output:
	// {
	//   "errors": [
	//     {
	//       "message": "query length 53 exceeds the maximum allowed query length of 50 bytes"
	//     }
	//   ]
	// }
}

func ExampleRestrictIntrospection() {
	allowKey := struct{}{}
	// only allow introspection if the function below returns true
	filter := func(ctx context.Context) bool {
		allow, found := ctx.Value(allowKey).(bool)
		return found && allow
	}
	schema := graphql.MustParseSchema(starwars.Schema, &starwars.Resolver{}, graphql.RestrictIntrospection(filter))

	query := `{
		__type(name: "Episode") {
			enumValues {
				name
			}
		}
	}`

	cases := []struct {
		name string
		ctx  context.Context
	}{
		{
			name: "Empty context",
			ctx:  context.Background(),
		},
		{
			name: "Introspection forbidden",
			ctx:  context.WithValue(context.Background(), allowKey, false),
		},
		{
			name: "Introspection allowed",
			ctx:  context.WithValue(context.Background(), allowKey, true),
		},
	}
	for _, c := range cases {
		fmt.Println(c.name, "result:")
		res := schema.Exec(c.ctx, query, "", nil)

		enc := json.NewEncoder(os.Stdout)
		enc.SetIndent("", "  ")
		err := enc.Encode(res)
		if err != nil {
			panic(err)
		}
	}
	// output:
	// Empty context result:
	// {
	//   "data": {}
	// }
	// Introspection forbidden result:
	// {
	//   "data": {}
	// }
	// Introspection allowed result:
	// {
	//   "data": {
	//     "__type": {
	//       "enumValues": [
	//         {
	//           "name": "NEWHOPE"
	//         },
	//         {
	//           "name": "EMPIRE"
	//         },
	//         {
	//           "name": "JEDI"
	//         }
	//       ]
	//     }
	//   }
	// }
}

func ExampleSchema_AST() {
	schema := graphql.MustParseSchema(starwars.Schema, nil)
	ast := schema.AST()

	for _, e := range ast.Enums {
		fmt.Printf("Enum %q has the following options:\n", e.Name)
		for _, o := range e.EnumValuesDefinition {
			fmt.Printf("  - %s\n", o.EnumValue)
		}
	}
	// output:
	// Enum "Episode" has the following options:
	//   - NEWHOPE
	//   - EMPIRE
	//   - JEDI
	// Enum "LengthUnit" has the following options:
	//   - METER
	//   - FOOT
}

func ExampleSchema_AST_generateEnum() {
	s := `
		type Query {
			currentSeason: Season!
		}

		"""
		Season represents a season of the year.
		"""
		enum Season {
			SPRING
			SUMMER
			AUTUMN
			WINTER
		}
	`

	gocode := `
{{ $enum := . }}
// {{ $enum.Desc }}
type {{ $enum.Name }} int

const (
	{{ range $i, $e :=  $enum.EnumValuesDefinition }}{{ if ne $i 0 }}{{ printf "\n\t" }}{{ end }}
		{{- $e.EnumValue | toVar }}{{ if eq $i 0 }} {{ $enum.Name }} = iota{{ end }}
	{{- end }}
)

var {{ $enum.Name | toLower }}Items = [...]string{
{{- range $i, $e :=  $enum.EnumValuesDefinition }}{{ if ne $i 0 }}{{ printf ", " }}{{ end }}
	{{- $e.EnumValue | quote }}
{{- end -}}
}

func (s {{ $enum.Name }}) String() string { return {{ $enum.Name | toLower }}Items[s] }

func (s *{{ $enum.Name }}) Deserialize(str string) {
	var found bool
	for i, v := range {{ $enum.Name | toLower }}Items {
		if v == str {
			found = true
			(*s) = {{ $enum.Name }}(i)
		}
	}
	if !found {
		panic("invalid value for enum {{ $enum.Name }}: " + str)
	}
}

func ({{ $enum.Name }}) ImplementsGraphQLType(name string) bool {
	return name == {{ $enum.Name | quote }}
}

func (s *{{ $enum.Name }}) UnmarshalGraphQL(input interface{}) error {
	var err error
	switch input := input.(type) {
	case string:
		s.Deserialize(input)
	default:
		err = fmt.Errorf("wrong type for {{ $enum.Name }}: %T", input)
	}
	return err
}
`

	funcs := template.FuncMap{
		"quote": func(s string) string {
			return `"` + s + `"`
		},
		"toLower": strings.ToLower,
		"toVar": func(s string) string {
			if len(s) == 0 {
				return s
			}
			return strings.ToUpper(s[:1]) + strings.ToLower(s[1:])
		},
	}

	tpl, err := template.New("enum").Funcs(funcs).Parse(gocode)
	if err != nil {
		panic(err)
	}

	opts := []graphql.SchemaOpt{
		graphql.UseStringDescriptions(),
	}
	schema := graphql.MustParseSchema(s, nil, opts...)
	ast := schema.AST()
	seasons := ast.Enums[0]

	err = tpl.Execute(os.Stdout, seasons)
	if err != nil {
		panic(err)
	}
	// output:
	// // Season represents a season of the year.
	// type Season int
	//
	// const (
	//	Spring Season = iota
	//	Summer
	//	Autumn
	//	Winter
	// )
	//
	// var seasonItems = [...]string{"SPRING", "SUMMER", "AUTUMN", "WINTER"}
	//
	// func (s Season) String() string { return seasonItems[s] }
	//
	// func (s *Season) Deserialize(str string) {
	// 	var found bool
	// 	for i, v := range seasonItems {
	// 		if v == str {
	// 			found = true
	// 			(*s) = Season(i)
	// 		}
	// 	}
	// 	if !found {
	// 		panic("invalid value for enum Season: " + str)
	// 	}
	// }
	//
	// func (Season) ImplementsGraphQLType(name string) bool {
	// 	return name == "Season"
	// }
	//
	// func (s *Season) UnmarshalGraphQL(input interface{}) error {
	// 	var err error
	// 	switch input := input.(type) {
	// 	case string:
	// 		s.Deserialize(input)
	// 	default:
	// 		err = fmt.Errorf("wrong type for Season: %T", input)
	// 	}
	// 	return err
	// }
}

func ExampleUseStringDescriptions() {
	s := `
	schema {
		query: Query
	}

	type Query {
		post(id: Int!): Post
	}

	"""
	Post represents a blog post.
	"""
	type Post {
		"Unique identifier of the post."
		id: ID!

		# The title field has no description.
		title: String!

		"""
		Tags of the post.
		"""
		# tags can be empty
		tags: [String!]!
	}
	`

	opts := []graphql.SchemaOpt{
		graphql.UseStringDescriptions(),
	}
	schema := graphql.MustParseSchema(s, nil, opts...)
	ast := schema.AST()

	post := ast.Objects[1]
	fmt.Printf("Field descriptions of the %q type:\n", post.TypeName())
	for _, f := range post.Fields {
		fmt.Printf("  field: %q, description: %q\n", f.Name, f.Desc)
	}
	// output:
	// Field descriptions of the "Post" type:
	//   field: "id", description: "Unique identifier of the post."
	//   field: "title", description: ""
	//   field: "tags", description: "Tags of the post."
}

// ExampleFieldTag demonstrates the use of the graphql field tag.
func Example_resolverFieldTag() {
	type resolver struct {
		Hello           string
		HelloUnderscore string `graphql:"_hello"`
		HelloLower      string `graphql:"hello"`
		HelloTitle      string `graphql:"Hello"`
		HelloUpper      string `graphql:"HELLO"`
	}

	sdl := `
	type Query {
		_hello: String!
		hello: String!
		Hello: String!
		HELLO: String!
	}`

	r := &resolver{
		Hello:           "This field is not used during query execution!",
		HelloLower:      "Hello, graphql!",
		HelloTitle:      "Hello, GraphQL!",
		HelloUnderscore: "Hello, _!",
		HelloUpper:      "Hello, GRAPHQL!",
	}

	query := `
	{
		_hello
		hello
		Hello
		HELLO
	}
	`

	schema := graphql.MustParseSchema(sdl, r, graphql.UseFieldResolvers())
	res := schema.Exec(context.Background(), query, "", nil)

	enc := json.NewEncoder(os.Stdout)
	enc.SetIndent("", "  ")
	err := enc.Encode(res)
	if err != nil {
		panic(err)
	}

	// output:
	// {
	//   "data": {
	//     "_hello": "Hello, _!",
	//     "hello": "Hello, graphql!",
	//     "Hello": "Hello, GraphQL!",
	//     "HELLO": "Hello, GRAPHQL!"
	//   }
	// }
}