bug: fix custom content-type overidden by json method (#1833)

* bug: fix custom content-type overided for json method

* fix format

---------

Co-authored-by: hulin <hulin2021@gmail.com>

Author: hulin32

src/async_impl/request.rs

@@ -440,8 +440,10 @@ impl RequestBuilder {
         if let Ok(ref mut req) = self.request {
             match serde_json::to_vec(json) {
                 Ok(body) => {
-                    req.headers_mut()
-                        .insert(CONTENT_TYPE, HeaderValue::from_static("application/json"));
+                    if !req.headers().contains_key(CONTENT_TYPE) {
+                        req.headers_mut()
+                            .insert(CONTENT_TYPE, HeaderValue::from_static("application/json"));
+                    }
                     *req.body_mut() = Some(body.into());
                 }
                 Err(err) => error = Some(crate::error::builder(err)),

src/blocking/request.rs

@@ -494,8 +494,10 @@ impl RequestBuilder {
         if let Ok(ref mut req) = self.request {
             match serde_json::to_vec(json) {
                 Ok(body) => {
-                    req.headers_mut()
-                        .insert(CONTENT_TYPE, HeaderValue::from_static("application/json"));
+                    if !req.headers().contains_key(CONTENT_TYPE) {
+                        req.headers_mut()
+                            .insert(CONTENT_TYPE, HeaderValue::from_static("application/json"));
+                    }
                     *req.body_mut() = Some(body.into());
                 }
                 Err(err) => error = Some(crate::error::builder(err)),

tests/blocking.rs

@@ -1,4 +1,8 @@
 mod support;
+
+use http::header::CONTENT_TYPE;
+use http::HeaderValue;
+use std::collections::HashMap;
 use support::*;
 
 #[test]
@@ -328,3 +332,33 @@ fn test_body_from_bytes() {
 
     assert_eq!(request.body().unwrap().as_bytes(), Some(body.as_bytes()));
 }
+
+#[test]
+#[cfg(feature = "json")]
+fn blocking_add_json_default_content_type_if_not_set_manually() {
+    let mut map = HashMap::new();
+    map.insert("body", "json");
+    let content_type = HeaderValue::from_static("application/vnd.api+json");
+    let req = reqwest::blocking::Client::new()
+        .post("https://google.com/")
+        .header(CONTENT_TYPE, &content_type)
+        .json(&map)
+        .build()
+        .expect("request is not valid");
+
+    assert_eq!(content_type, req.headers().get(CONTENT_TYPE).unwrap());
+}
+
+#[test]
+#[cfg(feature = "json")]
+fn blocking_update_json_content_type_if_set_manually() {
+    let mut map = HashMap::new();
+    map.insert("body", "json");
+    let req = reqwest::blocking::Client::new()
+        .post("https://google.com/")
+        .json(&map)
+        .build()
+        .expect("request is not valid");
+
+    assert_eq!("application/json", req.headers().get(CONTENT_TYPE).unwrap());
+}

tests/client.rs

@@ -1,6 +1,10 @@
 #![cfg(not(target_arch = "wasm32"))]
 mod support;
+
 use futures_util::stream::StreamExt;
+use http::header::CONTENT_TYPE;
+use http::HeaderValue;
+use std::collections::HashMap;
 use support::*;
 
 use reqwest::Client;
@@ -372,3 +376,33 @@ async fn test_allowed_methods() {
 
     assert!(resp.is_err());
 }
+
+#[test]
+#[cfg(feature = "json")]
+fn add_json_default_content_type_if_not_set_manually() {
+    let mut map = HashMap::new();
+    map.insert("body", "json");
+    let content_type = HeaderValue::from_static("application/vnd.api+json");
+    let req = Client::new()
+        .post("https://google.com/")
+        .header(CONTENT_TYPE, &content_type)
+        .json(&map)
+        .build()
+        .expect("request is not valid");
+
+    assert_eq!(content_type, req.headers().get(CONTENT_TYPE).unwrap());
+}
+
+#[test]
+#[cfg(feature = "json")]
+fn update_json_content_type_if_set_manually() {
+    let mut map = HashMap::new();
+    map.insert("body", "json");
+    let req = Client::new()
+        .post("https://google.com/")
+        .json(&map)
+        .build()
+        .expect("request is not valid");
+
+    assert_eq!("application/json", req.headers().get(CONTENT_TYPE).unwrap());
+}