Allow decoding same request multiple times

form.go

@@ -6,9 +6,11 @@
 package form
 
 import (
+	"bytes"
 	"encoding/json"
 	"encoding/xml"
 	"errors"
+	"io"
 	"io/ioutil"
 	"mime"
 	"net/http"
@@ -105,21 +107,18 @@ func parseContentType(r *http.Request) (string, error) {
 
 // JSON is a JSON decoder.
 func JSON(r *http.Request, v interface{}) error {
-	body, err := ioutil.ReadAll(r.Body)
-	if err != nil {
-		return err
-	}
-	return json.Unmarshal(body, v)
+	var buf bytes.Buffer
+	reader := io.TeeReader(r.Body, &buf)
+	r.Body = ioutil.NopCloser(&buf)
+	return json.NewDecoder(reader).Decode(v)
 }
 
 // XML is an XML decoder.
 func XML(r *http.Request, v interface{}) error {
-	body, err := ioutil.ReadAll(r.Body)
-	if err != nil {
-		return err
-	}
-
-	return xml.Unmarshal(body, v)
+	var buf bytes.Buffer
+	reader := io.TeeReader(r.Body, &buf)
+	r.Body = ioutil.NopCloser(&buf)
+	return xml.NewDecoder(reader).Decode(v)
 }
 
 // NewForm returns a post form decoder with the given schema decoder.

form_test.go

@@ -58,15 +58,17 @@ func TestJSON(t *testing.T) {
 		actual := login{}
 		r := httptest.NewRequest(http.MethodPost, "/", bytes.NewReader(test.body))
 		r.Header.Set("Content-Type", ContentTypeJSON)
-		err := Decode(r, &actual)
-		if test.shouldErr {
-			assert.NotNil(t, err)
-			continue
+		for i := 0; i < 3; i++ {
+			err := Decode(r, &actual)
+			if test.shouldErr {
+				assert.NotNil(t, err)
+				continue
+			}
+			assert.Nil(t, err)
+			expected := login{validated: true}
+			assert.Nil(t, json.Unmarshal(test.body, &expected))
+			assert.Equal(t, expected, actual)
 		}
-		assert.Nil(t, err)
-		expected := login{validated: true}
-		assert.Nil(t, json.Unmarshal(test.body, &expected))
-		assert.Equal(t, expected, actual)
 	}
 }
 
@@ -86,15 +88,17 @@ func TestXML(t *testing.T) {
 		actual := login{}
 		r := httptest.NewRequest(http.MethodPost, "/", bytes.NewReader(test.body))
 		r.Header.Set("Content-Type", ContentTypeXML)
-		err := Decode(r, &actual)
-		if test.shouldErr {
-			assert.NotNil(t, err)
-			continue
+		for i := 0; i < 3; i++ {
+			err := Decode(r, &actual)
+			if test.shouldErr {
+				assert.NotNil(t, err)
+				continue
+			}
+			assert.Nil(t, err)
+			expected := login{validated: true}
+			assert.Nil(t, xml.Unmarshal(test.body, &expected))
+			assert.Equal(t, expected, actual)
 		}
-		assert.Nil(t, err)
-		expected := login{validated: true}
-		assert.Nil(t, xml.Unmarshal(test.body, &expected))
-		assert.Equal(t, expected, actual)
 	}
 }