Handle mutlipart/form-data

Author: David Koblas

README.md

@@ -36,6 +36,24 @@ h := handler.New(&handler.Config{
 })
 ```
 
+### Using Multipart Form Uploads
+
+This handler supports th
+[GraphQL multipart request specification](https://github.com/jaydenseric/graphql-multipart-request-spec).
+All file uploads will be made available as the following Scalar that you can add to your GraphQL schemas
+
+```go
+var UploadScalar = graphql.NewScalar(graphql.ScalarConfig{
+	Name: "Upload",
+	ParseValue: func(value interface{}) interface{} {
+		if v, ok := value.(*handler.MultipartFile); ok {
+			return v
+		}
+		return nil
+	},
+})
+```
+
 ### Details
 
 The handler will accept requests with
@@ -70,6 +88,9 @@ depending on the provided `Content-Type` header.
   * **`application/graphql`**: The POST body will be parsed as GraphQL
     query string, which provides the `query` parameter.
 
+  * **`multipart/form-data`**: The POST body will be parsed as GraphQL
+    query string, which provides the `operations` parameter.
+    [GraphQL multipart request specification](https://github.com/jaydenseric/graphql-multipart-request-spec)
 
 ### Examples
 - [golang-graphql-playground](https://github.com/graphql-go/playground)

handler.go

@@ -3,8 +3,10 @@ package handler
 import (
 	"encoding/json"
 	"io/ioutil"
+	"mime/multipart"
 	"net/http"
 	"net/url"
+	"strconv"
 	"strings"
 
 	"github.com/graphql-go/graphql"
@@ -13,17 +15,24 @@ import (
 )
 
 const (
-	ContentTypeJSON           = "application/json"
-	ContentTypeGraphQL        = "application/graphql"
-	ContentTypeFormURLEncoded = "application/x-www-form-urlencoded"
+	ContentTypeJSON              = "application/json"
+	ContentTypeGraphQL           = "application/graphql"
+	ContentTypeFormURLEncoded    = "application/x-www-form-urlencoded"
+	ContentTypeMultipartFormData = "multipart/form-data"
 )
 
+type MultipartFile struct {
+	File   multipart.File
+	Header *multipart.FileHeader
+}
+
 type Handler struct {
 	Schema       *graphql.Schema
 	pretty       bool
 	graphiql     bool
 	playground   bool
 	rootObjectFn RootObjectFn
+	maxMemory    int64
 }
 type RequestOptions struct {
 	Query         string                 `json:"query" url:"query" schema:"query"`
@@ -57,7 +66,7 @@ func getFromForm(values url.Values) *RequestOptions {
 }
 
 // RequestOptions Parses a http.Request into GraphQL request options struct
-func NewRequestOptions(r *http.Request) *RequestOptions {
+func NewRequestOptions(r *http.Request, maxMemory int64) *RequestOptions {
 	if reqOpt := getFromForm(r.URL.Query()); reqOpt != nil {
 		return reqOpt
 	}
@@ -95,6 +104,89 @@ func NewRequestOptions(r *http.Request) *RequestOptions {
 
 		return &RequestOptions{}
 
+	case ContentTypeMultipartFormData:
+		if err := r.ParseMultipartForm(maxMemory); err != nil {
+			// fmt.Printf("Parse Multipart Failed %v", err)
+			return &RequestOptions{}
+		}
+
+		// @TODO handle array case...
+
+		operationsParam := r.FormValue("operations")
+		var opts RequestOptions
+		if err := json.Unmarshal([]byte(operationsParam), &opts); err != nil {
+			// fmt.Printf("Parse Operations Failed %v", err)
+			return &RequestOptions{}
+		}
+
+		mapParam := r.FormValue("map")
+		mapValues := make(map[string]([]string))
+		if len(mapParam) != 0 {
+			if err := json.Unmarshal([]byte(mapParam), &mapValues); err != nil {
+				// fmt.Printf("Parse map Failed %v", err)
+				return &RequestOptions{}
+			}
+		}
+
+		variables := opts
+
+		for key, value := range mapValues {
+			for _, v := range value {
+				if file, header, err := r.FormFile(key); err == nil {
+
+					// Now set the path in ther variables
+					var node interface{} = variables
+
+					parts := strings.Split(v, ".")
+					last := parts[len(parts)-1]
+
+					for _, vv := range parts[:len(parts)-1] {
+						// fmt.Printf("Doing vv=%s type=%T parts=%v\n", vv, node, parts)
+						switch node.(type) {
+						case RequestOptions:
+							if vv == "variables" {
+								node = opts.Variables
+							} else {
+								// panic("Invalid top level tag")
+								return &RequestOptions{}
+							}
+						case map[string]interface{}:
+							node = node.(map[string]interface{})[vv]
+						case []interface{}:
+							if idx, err := strconv.ParseInt(vv, 10, 64); err == nil {
+								node = node.([]interface{})[idx]
+							} else {
+								// panic("Unable to lookup index")
+								return &RequestOptions{}
+							}
+						default:
+							// panic(fmt.Errorf("Unknown type %T", node))
+							return &RequestOptions{}
+						}
+					}
+
+					data := &MultipartFile{File: file, Header: header}
+
+					switch node.(type) {
+					case map[string]interface{}:
+						node.(map[string]interface{})[last] = data
+					case []interface{}:
+						if idx, err := strconv.ParseInt(last, 10, 64); err == nil {
+							node.([]interface{})[idx] = data
+						} else {
+							// panic("Unable to lookup index")
+							return &RequestOptions{}
+						}
+					default:
+						// panic(fmt.Errorf("Unknown last type %T", node))
+						return &RequestOptions{}
+					}
+				}
+			}
+		}
+
+		return &opts
+
 	case ContentTypeJSON:
 		fallthrough
 	default:
@@ -119,7 +211,7 @@ func NewRequestOptions(r *http.Request) *RequestOptions {
 // user-provided context.
 func (h *Handler) ContextHandler(ctx context.Context, w http.ResponseWriter, r *http.Request) {
 	// get query
-	opts := NewRequestOptions(r)
+	opts := NewRequestOptions(r, h.maxMemory)
 
 	// execute graphql query
 	params := graphql.Params{
@@ -182,14 +274,15 @@ type Config struct {
 	GraphiQL     bool
 	Playground   bool
 	RootObjectFn RootObjectFn
+	MaxMemory    int64
 }
 
 func NewConfig() *Config {
 	return &Config{
-		Schema:     nil,
-		Pretty:     true,
-		GraphiQL:   true,
-		Playground: false,
+		Schema:    nil,
+		Pretty:    true,
+		GraphiQL:  true,
+		MaxMemory: 0,
 	}
 }
 
@@ -201,11 +294,17 @@ func New(p *Config) *Handler {
 		panic("undefined GraphQL schema")
 	}
 
+	maxMemory := p.MaxMemory
+	if maxMemory == 0 {
+		maxMemory = 32 << 20 // 32MB
+	}
+
 	return &Handler{
 		Schema:       p.Schema,
 		pretty:       p.Pretty,
 		graphiql:     p.GraphiQL,
 		playground:   p.Playground,
 		rootObjectFn: p.RootObjectFn,
+		maxMemory:    maxMemory,
 	}
 }