feat(enhancement): add SetContentType helper method

Author: jeevatkm

Diff for: multipart_test.go

@@ -353,8 +353,8 @@ func TestMultipartLargeFile(t *testing.T) {
 		c := dcnl()
 		resp, err := c.R().
 			SetFile("file", filepath.Join(getTestDataPath(), "test-img.png")).
-			SetMultipartBoundary("custom-boundary-"+strconv.FormatInt(time.Now().Unix(), 10)).
-			SetHeader("Content-Type", "image/png").
+			SetMultipartBoundary("custom-boundary-" + strconv.FormatInt(time.Now().Unix(), 10)).
+			SetContentType("image/png").
 			Post(ts.URL + "/upload")
 		assertNil(t, err)
 		assertNotNil(t, resp)
@@ -365,8 +365,8 @@ func TestMultipartLargeFile(t *testing.T) {
 		c := dcnl()
 		_, err := c.R().
 			SetFile("file", filepath.Join(getTestDataPath(), "test-img.png")).
-			SetMultipartBoundary(`"custom-boundary-"`+strconv.FormatInt(time.Now().Unix(), 10)).
-			SetHeader("Content-Type", "image/png").
+			SetMultipartBoundary(`"custom-boundary-"` + strconv.FormatInt(time.Now().Unix(), 10)).
+			SetContentType("image/png").
 			Post(ts.URL + "/upload")
 		assertNotNil(t, err)
 		assertEqual(t, "mime: invalid boundary character", err.Error())
@@ -616,8 +616,8 @@ func TestMultipartRequest_createMultipart(t *testing.T) {
 
 		req1 := c.R().
 			SetFile("file", filepath.Join(getTestDataPath(), "test-img.png")).
-			SetMultipartBoundary("custom-boundary-"+strconv.FormatInt(time.Now().Unix(), 10)).
-			SetHeader("Content-Type", "image/png")
+			SetMultipartBoundary("custom-boundary-" + strconv.FormatInt(time.Now().Unix(), 10)).
+			SetContentType("image/png")
 
 		mw := multipart.NewWriter(new(bytes.Buffer))
 		err := createMultipart(mw, req1)
@@ -638,7 +638,7 @@ func TestMultipartRequest_createMultipart(t *testing.T) {
 
 		req1 := c.R().
 			SetFile("file", filepath.Join(getTestDataPath(), "test-img.png")).
-			SetHeader("Content-Type", "image/png")
+			SetContentType("image/png")
 
 		mw := multipart.NewWriter(new(bytes.Buffer))
 		err := createMultipart(mw, req1)

Diff for: request.go

@@ -158,6 +158,14 @@ func (r *Request) WithContext(ctx context.Context) *Request {
 	return rr
 }
 
+// SetContentType method is a convenient way to set the header Content-Type in the request
+//
+//	client.R().SetContentType("application/json")
+func (r *Request) SetContentType(ct string) *Request {
+	r.SetHeader(hdrContentTypeKey, ct)
+	return r
+}
+
 // SetHeader method sets a single header field and its value in the current request.
 //
 // For Example: To set `Content-Type` and `Accept` as `application/json`.

Diff for: request_test.go

@@ -1594,7 +1594,7 @@ func TestRequestFileUploadAsReader(t *testing.T) {
 
 	resp, err := dcnldr().
 		SetBody(file).
-		SetHeader("Content-Type", "image/png").
+		SetContentType("image/png").
 		Post(ts.URL + "/upload")
 
 	assertError(t, err)
@@ -1606,7 +1606,7 @@ func TestRequestFileUploadAsReader(t *testing.T) {
 
 	resp, err = dcnldr().
 		SetBody(file).
-		SetHeader("Content-Type", "image/png").
+		SetContentType("image/png").
 		SetContentLength(true).
 		Post(ts.URL + "/upload")