Unable to add header for post method in dio in Flutter

I'm using **dio: ^3.0.4**. Any one please help me to find the solution for adding header. here my code:

FormData formData =
new FormData.fromMap({"files": await MultipartFile.fromFile(filePath.path, filename: 'photo')
});

----

Response response = await dio.post("***********",
data: formData,
onSendProgress: (int sent, int total) {
print("$sent $total");
},
options: Options(
headers: {
"authorization": "*************"
},
followRedirects: false,
validateStatus: (status) {
return status <= 500;
}
),
);

When i print the header.

> print(response.headers);

**Result:**

> flutter: content-type: text/html; charset=UTF-8 connection: close
> cache-control: no-cache, private transfer-encoding: chunked date: Thu,
> 07 Nov 2019 14:29:02 GMT server: Apache/2.4.18

There are some similar questions do not have answer <br>
But the following work for me <br>
Please use the following code snippet to set headers attribute

Dio dio = new Dio();
dio.options.headers["Authorization"] = "Bearer ${token}";
response = await dio.post(url, data: data);

Dio library key working perfectly fine in my case if we pass **small case** key value

For example,



Dio dio = new Dio();
dio.options.headers['content-Type'] = 'application/json';
dio.options.headers["authorization"] = "token ${token}";
response = await dio.post(url, data: data);

make sure you write key in **small case**, that's work for me.

This work for me after try differents ways to pass the argument to headers

Dio dio = new Dio();
dio.options.contentType = ContentType("application","x-www-form-urlencoded");
dio.options.headers[HttpHeaders.authorizationHeader] ="Basic $clientCredentials";

That's probably bug because I was not able to set it with lowercase `content-type`.

`Content-Type` works.

```dart
options.headers = {'Content-Type': 'application/json', ...request.headers};
```

Feel free to refer to

[To see links please register here]

```dart
dio.options.contentType = ContentType("application","x-www-form-urlencoded") as String;
```

In case of you use di in your projects and the dioclient is a singleton, this is how authorization is added to the call.

final response = await _dioClient.get(Endpoints.getDashboard,
queryParameters{'shopId':int.parse(shopId)},
options: Options(
headers: {
"authorization": "Bearer <your token>",
},
),
);

I'm using it like this:


_dio = Dio();
_dio.options.baseUrl = _baseUrl;
_dio.options.connectTimeout = 5000; //5s
_dio.options.receiveTimeout = 3000;
_dio.options.contentType = 'application/json';
_dio.options.headers['Content-Type'] = 'application/json';
_dio.options.headers["Authorization"] = "Bearer 284|NRx1PaEY2HbwHi2XMzGdxg9UJ5rGXkNMcYyNXkqH";
_dio.options.followRedirects = false;
_dio.options.validateStatus = (status) {
return status! < 500;
};