Update GQLgen test client to work with multipart form data (#1418)

* Update GQLgen test client to work with multipart form data

Update the GQLgen to support multipart form data, like those present
within the fileupload examples.

- Add missing space between "unsupported encoding " and failing
  content-type header error

* Add WithFiles client option for fileupload GQLgen client tests

Add a `WithFiles` GQLgen client option to support the fileupload input
within tests, using the core Golang `os` package and File type, which
converts `os.File`s to their appropriate multipart form data within a
request.

- If there are no files this should just simply convert a
  `application/json` Content-Type to supported `multipart/form-data`

* Update fileupload test to use GQLgen test client

Update the fileupload test to use the GQLgen test client and `WithFiles`
option to remove the need for `createUploadRequest` helper with raw http
posts

- Fix setting the Content Type by using the appropriate `http` package
  function to dectect it

  + https://godoc.org/net/http#DetectContentType

* Update WithFiles option test with multipart Reader

* Update file upload tests `WithFiles` option

Update the file upload tests to use the GQL test client and its
`WithFiles` option to remove the need for a custom raw HTTP post request
builder `createUploadRequest`.

- Also update `WithFiles` option to group & map identical files; e.g.

  ```
    { "0": ["variables.req.0.file", "variables.req.1.file"] }
  ```

* Make sure `WithFiles` does not add duplicates to multipart form data

* Fix use of byte vs string in `WithFiles` tests

client/client.go

@@ -9,6 +9,7 @@ import (
 	"io/ioutil"
 	"net/http"
 	"net/http/httptest"
+	"regexp"
 
 	"github.com/mitchellh/mapstructure"
 )
@@ -120,15 +121,18 @@ func (p *Client) newRequest(query string, options ...Option) (*http.Request, err
 		option(bd)
 	}
 
-	switch bd.HTTP.Header.Get("Content-Type") {
-	case "application/json":
+	contentType := bd.HTTP.Header.Get("Content-Type")
+	switch {
+	case regexp.MustCompile(`multipart/form-data; ?boundary=.*`).MatchString(contentType):
+		break
+	case "application/json" == contentType:
 		requestBody, err := json.Marshal(bd)
 		if err != nil {
 			return nil, fmt.Errorf("encode: %w", err)
 		}
 		bd.HTTP.Body = ioutil.NopCloser(bytes.NewBuffer(requestBody))
 	default:
-		panic("unsupported encoding" + bd.HTTP.Header.Get("Content-Type"))
+		panic("unsupported encoding " + bd.HTTP.Header.Get("Content-Type"))
 	}
 
 	return bd.HTTP, nil

client/client_test.go

@@ -1,9 +1,12 @@
 package client_test
 
 import (
+	"bytes"
 	"encoding/json"
 	"io/ioutil"
+	"mime/multipart"
 	"net/http"
+	"net/textproto"
 	"testing"
 
 	"github.com/99designs/gqlgen/client"
@@ -39,6 +42,44 @@ func TestClient(t *testing.T) {
 	require.Equal(t, "bob", resp.Name)
 }
 
+func TestClientMultipartFormData(t *testing.T) {
+	h := http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		bodyBytes, err := ioutil.ReadAll(r.Body)
+		require.NoError(t, err)
+		require.Contains(t, string(bodyBytes), `Content-Disposition: form-data; name="operations"`)
+		require.Contains(t, string(bodyBytes), `{"query":"mutation ($input: Input!) {}","variables":{"file":{}}`)
+		require.Contains(t, string(bodyBytes), `Content-Disposition: form-data; name="map"`)
+		require.Contains(t, string(bodyBytes), `{"0":["variables.file"]}`)
+		require.Contains(t, string(bodyBytes), `Content-Disposition: form-data; name="0"; filename="example.txt"`)
+		require.Contains(t, string(bodyBytes), `Content-Type: text/plain`)
+		require.Contains(t, string(bodyBytes), `Hello World`)
+
+		w.Write([]byte(`{}`))
+	})
+
+	c := client.New(h)
+
+	var resp struct{}
+	c.MustPost("{ id }", &resp,
+		func(bd *client.Request) {
+			bodyBuf := &bytes.Buffer{}
+			bodyWriter := multipart.NewWriter(bodyBuf)
+			bodyWriter.WriteField("operations", `{"query":"mutation ($input: Input!) {}","variables":{"file":{}}`)
+			bodyWriter.WriteField("map", `{"0":["variables.file"]}`)
+
+			h := make(textproto.MIMEHeader)
+			h.Set("Content-Disposition", `form-data; name="0"; filename="example.txt"`)
+			h.Set("Content-Type", "text/plain")
+			ff, _ := bodyWriter.CreatePart(h)
+			ff.Write([]byte("Hello World"))
+			bodyWriter.Close()
+
+			bd.HTTP.Body = ioutil.NopCloser(bodyBuf)
+			bd.HTTP.Header.Set("Content-Type", bodyWriter.FormDataContentType())
+		},
+	)
+}
+
 func TestAddHeader(t *testing.T) {
 	h := http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
 		require.Equal(t, "ASDF", r.Header.Get("Test-Key"))

client/withfilesoption.go

@@ -0,0 +1,133 @@
+package client
+
+import (
+	"bytes"
+	"encoding/json"
+	"fmt"
+	"io/ioutil"
+	"mime/multipart"
+	"net/http"
+	"net/textproto"
+	"os"
+	"strings"
+)
+
+type fileFormDataMap struct {
+	mapKey string
+	file   *os.File
+}
+
+func findFiles(parentMapKey string, variables map[string]interface{}) []*fileFormDataMap {
+	files := []*fileFormDataMap{}
+	for key, value := range variables {
+		if v, ok := value.(map[string]interface{}); ok {
+			files = append(files, findFiles(parentMapKey+"."+key, v)...)
+		} else if v, ok := value.([]map[string]interface{}); ok {
+			for i, arr := range v {
+				files = append(files, findFiles(fmt.Sprintf(`%s.%s.%d`, parentMapKey, key, i), arr)...)
+			}
+		} else if v, ok := value.([]*os.File); ok {
+			for i, file := range v {
+				files = append(files, &fileFormDataMap{
+					mapKey: fmt.Sprintf(`%s.%s.%d`, parentMapKey, key, i),
+					file:   file,
+				})
+			}
+		} else if v, ok := value.(*os.File); ok {
+			files = append(files, &fileFormDataMap{
+				mapKey: parentMapKey + "." + key,
+				file:   v,
+			})
+		}
+	}
+
+	return files
+}
+
+// WithFiles encodes the outgoing request body as multipart form data for file variables
+func WithFiles() Option {
+	return func(bd *Request) {
+		bodyBuf := &bytes.Buffer{}
+		bodyWriter := multipart.NewWriter(bodyBuf)
+
+		//-b7955bd2e1d17b67ac157b9e9ddb6238888caefc6f3541920a1debad284d
+		// Content-Disposition: form-data; name="operations"
+		//
+		// {"query":"mutation ($input: Input!) {}","variables":{"input":{"file":{}}}
+		requestBody, _ := json.Marshal(bd)
+		bodyWriter.WriteField("operations", string(requestBody))
+
+		// --b7955bd2e1d17b67ac157b9e9ddb6238888caefc6f3541920a1debad284d
+		// Content-Disposition: form-data; name="map"
+		//
+		// `{ "0":["variables.input.file"] }`
+		// or
+		// `{ "0":["variables.input.files.0"], "1":["variables.input.files.1"] }`
+		// or
+		// `{ "0": ["variables.input.0.file"], "1": ["variables.input.1.file"] }`
+		// or
+		// `{ "0": ["variables.req.0.file", "variables.req.1.file"] }`
+		mapData := ""
+		filesData := findFiles("variables", bd.Variables)
+		filesGroup := [][]*fileFormDataMap{}
+		for _, fd := range filesData {
+			foundDuplicate := false
+			for j, fg := range filesGroup {
+				f1, _ := fd.file.Stat()
+				f2, _ := fg[0].file.Stat()
+				if os.SameFile(f1, f2) {
+					foundDuplicate = true
+					filesGroup[j] = append(filesGroup[j], fd)
+				}
+			}
+
+			if !foundDuplicate {
+				filesGroup = append(filesGroup, []*fileFormDataMap{fd})
+			}
+		}
+		if len(filesGroup) > 0 {
+			mapDataFiles := []string{}
+
+			for i, fileData := range filesGroup {
+				mapDataFiles = append(
+					mapDataFiles,
+					fmt.Sprintf(`"%d":[%s]`, i, strings.Join(collect(fileData, wrapMapKeyInQuotes), ",")),
+				)
+			}
+
+			mapData = `{` + strings.Join(mapDataFiles, ",") + `}`
+		}
+		bodyWriter.WriteField("map", mapData)
+
+		// --b7955bd2e1d17b67ac157b9e9ddb6238888caefc6f3541920a1debad284d
+		// Content-Disposition: form-data; name="0"; filename="tempFile"
+		// Content-Type: text/plain; charset=utf-8
+		// or
+		// Content-Type: application/octet-stream
+		//
+		for i, fileData := range filesGroup {
+			h := make(textproto.MIMEHeader)
+			h.Set("Content-Disposition", fmt.Sprintf(`form-data; name="%d"; filename="%s"`, i, fileData[0].file.Name()))
+			b, _ := ioutil.ReadFile(fileData[0].file.Name())
+			h.Set("Content-Type", http.DetectContentType(b))
+			ff, _ := bodyWriter.CreatePart(h)
+			ff.Write(b)
+		}
+		bodyWriter.Close()
+
+		bd.HTTP.Body = ioutil.NopCloser(bodyBuf)
+		bd.HTTP.Header.Set("Content-Type", bodyWriter.FormDataContentType())
+	}
+}
+
+func collect(strArr []*fileFormDataMap, f func(s *fileFormDataMap) string) []string {
+	result := make([]string, len(strArr))
+	for i, str := range strArr {
+		result[i] = f(str)
+	}
+	return result
+}
+
+func wrapMapKeyInQuotes(s *fileFormDataMap) string {
+	return fmt.Sprintf("\"%s\"", s.mapKey)
+}