Fix ShouldBindBodyWith method

README.md

@@ -1989,9 +1989,9 @@ func SomeHandler(c *gin.Context) {
 }
 ```
 
-* `c.ShouldBindBodyWith` stores body into the context before binding. This has
-a slight impact to performance, so you should not use this method if you are
-enough to call binding at once.
+* `c.ShouldBindBodyWith` stores body into the context before binding, and it
+does not consume the request body. This has a slight impact to performance,
+so you should not use this method if you are enough to call binding at once.
 * This feature is only needed for some formats -- `JSON`, `XML`, `MsgPack`,
 `ProtoBuf`. For other formats, `Query`, `Form`, `FormPost`, `FormMultipart`,
 can be called by `c.ShouldBind()` multiple times without any damage to

context.go

@@ -5,6 +5,7 @@
 package gin
 
 import (
+	"bytes"
 	"errors"
 	"fmt"
 	"io"
@@ -706,7 +707,7 @@ func (c *Context) ShouldBindWith(obj interface{}, b binding.Binding) error {
 // ShouldBindBodyWith is similar with ShouldBindWith, but it stores the request
 // body into the context, and reuse when it is called again.
 //
-// NOTE: This method reads the body before binding. So you should use
+// NOTE: This method copies the body before binding. So you should use
 // ShouldBindWith for better performance if you need to call only once.
 func (c *Context) ShouldBindBodyWith(obj interface{}, bb binding.BindingBody) (err error) {
 	var body []byte
@@ -720,6 +721,8 @@ func (c *Context) ShouldBindBodyWith(obj interface{}, bb binding.BindingBody) (e
 		if err != nil {
 			return err
 		}
+		c.Request.Body.Close()
+		c.Request.Body = ioutil.NopCloser(bytes.NewBuffer(body))
 		c.Set(BodyBytesKey, body)
 	}
 	return bb.BindBody(body, obj)

context_test.go

@@ -1761,6 +1761,21 @@ func TestContextShouldBindBodyWith(t *testing.T) {
 			assert.NoError(t, c.ShouldBindBodyWith(&objB, tt.bindingB))
 			assert.Equal(t, typeB{"BAR"}, objB)
 		}
+		// not affect the request body
+		{
+			// After it binds, other bind methods can bind without EOF error.
+			w := httptest.NewRecorder()
+			c, _ := CreateTestContext(w)
+			c.Request, _ = http.NewRequest(
+				"POST", "http://example.com", bytes.NewBufferString(tt.bodyA),
+			)
+			objA := typeA{}
+			assert.NoError(t, c.ShouldBindBodyWith(&objA, tt.bindingA))
+			assert.Equal(t, typeA{"FOO"}, objA)
+			anotherOjbA := typeA{}
+			assert.NoError(t, c.ShouldBindWith(&anotherOjbA, tt.bindingA))
+			assert.Equal(t, typeA{"FOO"}, anotherOjbA)
+		}
 	}
 }