Extended 'file' custom widget doesn't get the uploaded file

Describe the bug I am extending the file widget through getWidget('file') to achieve some custom validation of an uploaded .json. After some guessing/research I found out just class components are supported:

import CMS from 'netlify-cms-app'
import React, { PureComponent } from 'react'

const FileControl = CMS.getWidget('file')

class JSONControl extends PureComponent {
  isValid = () => ({ error: { message: 'Your error message.' } })

  render() {
    return <FileControl.control {...this.props} />
  }
}


export default JSONControl

To Reproduce When I try to upload a file after clicking “choose file” and selecting it from the media library (uploads successfully) it doesn’t get assigned as value to the field and the field still shows “choose file” as if nothing happened.

Expected behavior My aim here is to upload such file and on “publish” perform the isValid validation that I will implement. Therefore I need to have access to the file.

Applicable Versions: netlify-cms-core 2.12.1 netlify-cms-app 2.9.6

CMS configuration The relevant CMS config for that file is:

            {
              label: 'JSON',
              name: 'JSON',
              widget: 'JSON',
            },

[erezrokah]

@sleepingkiwi FYI, I’m actually refactoring the way the CMS is handling assets as a part of https://github.com/netlify/netlify-cms/issues/1472.

There are numerous bugs related to assets not shown in the CMS UI as they have not been published yet to the site: https://github.com/netlify/netlify-cms/issues/2953 https://github.com/netlify/netlify-cms/issues/1750 https://github.com/netlify/netlify-cms/issues/2332 https://github.com/netlify/netlify-cms/issues/2516

In short the getAsset will try to retrieve the asset from the UI state and fallback to get it from the repo (and not the published site). That meant changing getAsset to return a promise that resolves with the asset url instead of just a string.

[sleepingkiwi]

Fantastic, thanks for your work on that @erezrokah I think that’s exactly how I’d want getAsset to work for our use cases. I’m excited to see that land!