How to send Dio with Image Picker null data-CodePudding

I used to Image Picker Plug-in When sending when sending the data to server.

But, There is no problem sending the image to the server, but problems occur when I do not send the image.

I tried some things, but I failed. I want to know how I can send it without data in the image picker.

// image picker

final pickedFile = await ImagePicker.platform
        .pickImage(source: ImageSource.gallery, imageQuality: 50);

img = pickedFile.path;
var data = {
 ...
 , 'img' : img
}

....

// formdata

FormData formData = FormData.fromMap({
    ...
**case1** : 'img': await MultipartFile.fromFile(data['img']) // _TypeError (type 'Null' is not a subtype of type 'String')
**case2** : 'img': await MultipartFile.fromFile(data['img'].toString())
// FileSystemException (FileSystemException: Cannot retrieve length of file, path = 'null' (OS Error: No such file or directory, errno = 2))
**case3** : 'img': await MultipartFile?.fromFile(data['img']!) // _CastError (Null check operator used on a null value)
});

CodePudding user response：

you can use like this :

var data = {
  'img' : img
};

// formdata

FormData formData = FormData.fromMap({
'img': data['img'] == null ? null : await MultipartFile.fromFile(data['img']) 
});

it will send image data img parameter as null when image path is null.

CodePudding user response：

In Dart you can use ?? to specify a value when a variable is null, in your example you can write:

// image picker

final pickedFile = await ImagePicker.platform
        .pickImage(source: ImageSource.gallery, imageQuality: 50);

img = pickedFile.path;
var data = {
 ...
 , 'img' : img ?? 'the data you want to send if img is null'
}

// formdata

FormData formData = FormData.fromMap({
'img': await MultipartFile.fromFile(data['img'])
});