MultipartFile Upload: Converting object to an encodable object failed: Instance of 'FormData'

[lllleow]

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Issue Info

Info	Value
Platform Name	Flutter
Platform Version	1.17.2
Dio Version	3.0.9
Android Studio / Xcode Version	VSCode / Xcode 11
Repro rate	100%

Issue Description and Steps

Hello, i am trying to upload an image to a server. I've used the guides provided in the documentation to get the process started.

The error message that i am receiving is:
DioError [DioErrorType.DEFAULT]: Converting object to an encodable object failed: Instance of 'FormData'

My code is:

[stale]

This issue has been automatically marked as stale because it has not had recent activity. It will be closed if no further activity occurs. If this is still an issue, please make sure it is up to date and if so, add a comment that this is still an issue to keep it open. Thank you for your contributions.

[yangtao2016]

我也碰到了相同的问题：Converting object to an encodable object failed: Instance of 'FormData

[stale]

This issue has been automatically marked as stale because it has not had recent activity. It will be closed if no further activity occurs. If this is still an issue, please make sure it is up to date and if so, add a comment that this is still an issue to keep it open. Thank you for your contributions.

[ejrgeek]

I'm having the same error:

Code:

MultipartFile file = await MultipartFile.fromFile(image.path);
responseDio = await dio.request(
    endpointUpdateImageProfile,
    options: Options(
    method: "POST",
        headers: {
            'Content-Type': 'multipart/form-data',
            'Authorization': 'token $token',
        },
    ),
    data: {'profile': file},
);

Error:

ERRO: DioError [DioErrorType.DEFAULT]: Converting object to an encodable object failed: Instance of 'MultipartFile'
I/flutter ( 6127): #0      _JsonStringifier.writeObject  (dart:convert/json.dart:687:7))
I/flutter ( 6127): #1      _JsonStringifier.writeMap  (dart:convert/json.dart:768:7))
I/flutter ( 6127): #2      _JsonStringifier.writeJsonValue  (dart:convert/json.dart:723:21))
I/flutter ( 6127): #3      _JsonStringifier.writeObject  (dart:convert/json.dart:678:9))
I/flutter ( 6127): #4      _JsonStringStringifier.printOn  (dart:convert/json.dart:876:17))
I/flutter ( 6127): #5      _JsonStringStringifier.stringify  (dart:convert/json.dart:861:5))
I/flutter ( 6127): #6      JsonEncoder.convert  (dart:convert/json.dart:261:30))
I/flutter ( 6127): #7      JsonCodec.encode  (dart:convert/json.dart:171:45))
I/flutter ( 6127): #8      DefaultTransformer.transformRequest 
package:dio/src/transformer.dart:62
I/flutter ( 6127): #9      DioMixin._transformData 
package:dio/src/dio.dart:1014
I/flutter ( 6127): #10     DioMixin._dispatchRequest 
package:dio/src/dio.dart:921
I/flutter ( 6127): #11     DioMixin._request._interceptorWrapper.<anonymous closure>.<anonymous closure>.<anonymous closure> 
package:dio/src/dio.dart:849
I/flutter ( 6127): #12     DioM

[chuongdevJC]

Did anyone resolve this issue pls ?

[Jagrajsinghji]

Try adding MediaType

MultipartFile mFile = await MultipartFile.fromFile(
      photo.path, filename: fileName,
      contentType: MediaType("image", fileName.split(".").last),);

The MediaType class is defined in http_parser, so make sure you use ths package

[pedrolacerda81]

Try adding MediaType

MultipartFile mFile = await MultipartFile.fromFile(
      photo.path, filename: fileName,
      contentType: MediaType("image", fileName.split(".").last),);

The MediaType class is defined in http_parser, so make sure you use ths package

@Jagrajsinghji added and still same error

[kateile]

same error. Any solution

[ahmedalrifai]

Any solution am having the same issue?

[MarcoGolin]

same error. Any solution? =(

[Jagrajsinghji]

Could anyone of you share you code snippet?

[MarcoGolin]

Could anyone of you share you code snippet?

solved, I wasn't using the FormData correctly, trying to send as Json

[abdelrahmanelmarakby]

Could anyone of you share you code snippet?

solved, I wasn't using the FormData correctly, trying to send as Json

tell us how did you solved this

[secret3579]

Could anyone of you share you code snippet?

solved, I wasn't using the FormData correctly, trying to send as Json

Please give your code example for this issue?

[tikkwi]

hope this help

     final file = await dio.MultipartFile.fromFile(
        _image?.path ?? "",
        filename: _image?.name,
      );

      final body = dio.FormData.fromMap({
        "email": _emailController.text,
        "password": _passwordController.text,
        "name": _nameController.text,
        "phone": _phoneController.text,
        "file": file
      });

[icemanbsi]

I have similar problem and I think I know the answer. We are looking at the wrong place.
The issue is triggered by jsonEncode function which trying to encode FormData instance. Since the FormData cannot be encoded to json string, it will trigger this error.

So the next step is find out where you place your debug print or similar function which called the jsonEncode. It might be on your interpreter too.

[devmemory]

I have similar problem and I think I know the answer. We are looking at the wrong place. The issue is triggered by jsonEncode function which trying to encode FormData instance. Since the FormData cannot be encoded to json string, it will trigger this error.

So the next step is find out where you place your debug print or similar function which called the jsonEncode. It might be on your interpreter too.

Thanks for icemanbsi. I could figure out why I faced this error.
According to what is written here, the problem was where I print whenever I call an API. And to see the request options without debugging mode, I'm configuring some parts.
And one of them was where I encode requestOptions.data. And after I blocked that part conditionally, I could solve it perfectly. :)

[zzz1029335886]

The problem occurred on log printing json.encode the data extends InterceptorsWrapper

[sulthanalihsan]

The problem occurred on log printing json.encode the data extends InterceptorsWrapper

how you solve that problem?

[Oliul-Hasnat-Rafi]

FormData data = FormData.fromMap({
'key': 'f8b0266d23d2f048bb5.',
'image': await MultipartFile.fromFile(filePath, filename: filename)
});
var response =
await dio.post('https://api.imgbb.com/1/upload', data: data);

it's work for me

[dakshatsuraasa]

same issue no solution

[MalikAbdMusleh]

Could anyone of you share you code snippet?

solved, I wasn't using the FormData correctly, trying to send as Json

worked thanks ♥ ♥