POST a file with React.js

Question

The end user is supposed to upload through a file browser an excel file:

Answer 1

Passing a file to the backend is done via multipart/form-data forms.

If you inspect the request that you send to the backend right now, you will see that your request does not send ( probably ) a multipart/form-data.

You can check for reference What does enctype='multipart/form-data' mean? question.

Your code should look something like :

callUploadXLS: {
    remote( state, file ) {
                // ^ make sure that `file` here is the same target.files[0]. It should be `File` Object

      // Will turn your form to `multipart/form-data`
      var data = new FormData();
      data.append('file', file);

      const url = `${base}/vendor/form`;
      return $http.instance.api.post( url, data );

    },
    success: Actions.XLSUploaded,
    error: Actions.fail
}