Issue with react-proxy, forwardRefs & decorators

[dslounge]

🐛 Bug Report

I'm having problems upgrading a project from RN 55 to RN 58.6
(UPDATE: this also occurs on 59, repro: https://github.com/dslounge/rnDecorators59).

My project has been using styled-components for a long time and it worked well. As I'm upgrading this project to RN 58.6, the app breaks due to issues with the withTheme decorator and react-proxy. Here are a few screenshots:

The error I'm getting:

The error location. createClassProxy.js from react-proxy doesn't handle forwardRefs:

This is a sample of the code that breaks. (repro: https://github.com/dslounge/rnDecorators59)

import React from "react";
import { withTheme } from "styled-components/native";
import { Text, View } from "react-native";

// THIS DOESN'T WORK
@withTheme
export class Button extends React.Component {
  render() {
    const { theme } = this.props;

    return (
      <View>
        <Text style={theme.buttonColor}>some text</Text>
      </View>
    );
  }
}

//THIS WORKS:
// class ButtonUI extends React.Component {
//   render() {
//     const { theme } = this.props;

//     return (
//       <View>
//         <Text style={{ color: theme.buttonColor }}>this should be red</Text>
//       </View>
//     );
//   }
// }

// export const Button = withTheme(ButtonUI);

My babel configuration seems to be fine:

{
  "presets": ["module:metro-react-native-babel-preset"],
  "plugins": [
    ["@babel/plugin-proposal-decorators", { "legacy": true }],
    ["@babel/plugin-proposal-export-namespace-from"]
  ]
}

I don't quite understand why this would break with an upgrade. As far as I know, styled-components has been using forwardRefs for a long time, and react-proxy hasn't changed in a long time either. I can only think that the breaking change is the babel upgrade.

This was my babelrc before upgrading:

{
  "presets": ["react-native-stage-0/decorator-support"],
  "env": {
    "development": {
      "plugins": ["transform-react-jsx-source"]
    }
  }
}

I'm not sure if react-native-stage-0/decorator-support behaves differently from @babel/plugin-proposal-decorators.

The only other thing I can think of is that there's some underlying change with Metro? I would love to understand what I'm missing here.

Related Issues:

I've looked for answers, I haven't found much, but some people are having this issue:

• in the StyledComponents repo: Cannot create styled-component for component [object Object] styled-components/styled-components#2233
• In the React Native repo: Using HOC with Wrapper Forwarding refs via es7 Decorators. Throw error "Expected a constructor" #24452
• React Proxy repo: Does not work with React 16.3 forwardRef gaearon/react-proxy#82

To Reproduce

• Create a new RN 59 project
• Add decorator support to an RN project and install styled-components
• Make a component and try to use @withTheme decorator from styled-components
• Get Expected a constructor error.

I've created a repo reproducing this issue: https://github.com/dslounge/rnDecorators59

Expected Behavior

I'm expecting my existing use of styled-components withTheme decorator to work just like it worked in RN 55.

Code Example

Repo reproducing the issue: https://github.com/dslounge/rnDecorators59

Environment

  React Native Environment Info:
    System:
      OS: macOS 10.14
      CPU: (4) x64 Intel(R) Core(TM) i5-4278U CPU @ 2.60GHz
      Memory: 292.31 MB / 8.00 GB
      Shell: 5.3 - /bin/zsh
    Binaries:
      Node: 10.13.0 - ~/.nvm/versions/node/v10.13.0/bin/node
      Yarn: 1.10.1 - /usr/local/bin/yarn
      npm: 6.4.1 - ~/.nvm/versions/node/v10.13.0/bin/npm
      Watchman: 4.7.0 - /usr/local/bin/watchman
    SDKs:
      iOS SDK:
        Platforms: iOS 12.1, macOS 10.14, tvOS 12.1, watchOS 5.1
      Android SDK:
        API Levels: 19, 21, 23, 24, 25, 26, 27, 28
        Build Tools: 19.1.0, 23.0.1, 23.0.3, 24.0.3, 25.0.1, 25.0.2, 25.0.3, 26.0.1, 26.0.2, 26.0.3, 27.0.3, 28.0.2, 28.0.3
        System Images: android-28 | Google Play Intel x86 Atom
    IDEs:
      Android Studio: 3.2 AI-181.5540.7.32.5014246
      Xcode: 10.1/10B61 - /usr/bin/xcodebuild
    npmPackages:
      react: 16.8.3 => 16.8.3
      react-native: 0.59.5 => 0.59.5

[brentvatne]

it seems like withTheme isn't exported from styled-components/native but rather from styled-components: https://snack.expo.io/@notbrent/vigorous-popsicle

edit: here's a full example with the App.js from the original issue included as well: https://snack.expo.io/@notbrent/vigorous-popsicle-lol

edit 2: perhaps this only confirms that the issue didn't exist as far back as 0.57 ;P

[brentvatne]

confirmed it's a React.forwardRef issue:

import React from "react";
import { Text, View } from "react-native";

// this works
function withLol(Component) {
  class MyThemedThing extends React.Component {
    render() {
      return <Component theme={{buttonColor: 'green'}} {...this.props} />
    }
  }

  return MyThemedThing;
}

// this doesn't work
function withForwardRef(Component) {
  const WithForwardRef = React.forwardRef((props, ref) => {
    return <Component theme={{buttonColor: 'green'}} {...props} ref={ref} />;
  });

  return WithForwardRef;
}

@withForwardRef
export class Button extends React.Component {
  render() {
    const { theme } = this.props;

    return (
      <View>
        <Text style={{color: theme.buttonColor}}>some text</Text>
      </View>
    );
  }
}

[elicwhite]

@brentvatne, does forwardRef work as expected when used without decorators? Does it work with decorators in a new project?

[brentvatne]

@TheSavior - it works without decorators, yeah (const Button = withForwardRef(BaseButton) works). by new project do you mean a blank react-native init project? this is basically what @dslounge provided but with decorator babel plugin enabled

[dslounge]

I think it ultimately comes down to this line in react-proxy. https://github.com/gaearon/react-proxy/blob/1.x/src/createClassProxy.js#L102. I'm just not sure why this started acting up all of a sudden with a react-native upgrade.

[ken0x0a]

Same problem here after start using yarn workspace.

When using single project (not monorepo), React.forwardRef was working fine. hmm...

[api182]

I'm having this problem with 0.59, not using forwardRef but I am using MobX decorators...

[kelset]

Hey everyone, I was looking a bit closer at this issue today and I am concerned that this will affect more and more people, given that new versions of popular libraries like redux-react (v6 > v7 update) and mobx-react (v5 > v6 update) started using decorators.

I found that apparently the reason why this started happening after the react-native upgrade lies in Metro's HMR facebook/metro#272

And (back in December!) @gaearon wrote that

Again, if there’s a bug or missing thing in react-proxy I’d be happy to take a fix and close this. Did anyone send a PR?

So my best guess would be that:

• this workaround should still be a viable solution HMR transform breaks React.forwardRef metro#272 (comment)
• a PR to react-proxy would be the best way to try and fix this in the long term
• the FB team is working on a new HMR (https://facebook.github.io/react-native/blog/2019/06/12/react-native-open-source-update#user-feedback) so maybe it could be worth waiting for that...? not sure about the timings around that tbh.

Sorry, I don't have a perfect solution for this atm 😓But I hope that the new information can help coming up with a plan 🤞

[gaearon]

We're going to get rid of react-proxy and that approach in the close future.

[wenkangzhou]

import { withTheme } from 'styled-components'

class SomeComp extends React.Component {
  render() {
    console.log(this.props.theme);
  }
}

export default withTheme(SomeComp);

this works for me

[gaearon]

react-proxy has been deleted in master.

We've replaced the transform with a different one that doesn't suffer from this issues.
The fix is expected to land in React Native 0.61.

See #18899 (comment) for details.

[dslounge]

If you are having this issue when upgrading to RN 59, some of the workarounds written above might not work. You can change this line in node_modules/metro/src/lib/parseOptionsFromUrl.js and use patch-package

diff --git a/node_modules/metro/src/lib/parseOptionsFromUrl.js b/node_modules/metro/src/lib/parseOptionsFromUrl.js
index 3a55687..331bcc1 100644
--- a/node_modules/metro/src/lib/parseOptionsFromUrl.js
+++ b/node_modules/metro/src/lib/parseOptionsFromUrl.js
@@ -113,7 +113,7 @@ function parseOptionsFromUrl(reqUrl, platforms) {
     options: {
       customTransformOptions,
       dev,
-      hot: true,
+      hot: false,
       minify,
       platform,
       onProgress: null,

[gaearon]

In general I would recommend avoiding the use of decorators, as they're not a stable language feature yet. (Although, as I said, this specific problem will be fixed in 0.61)

[JoshWalshaw]

In general I would recommend avoiding the use of decorators, as they're not a stable language feature yet. (Although, as I said, this specific problem will be fixed in 0.61)

I don't suppose you know how long we'll be waiting for the 0.61 release by any chance do you?

[kelset]

the cut of 0.61 will likely happen over the next couple weeks - sorry it's taking so long again :(

[gaearon]

0.61 is out with a fix.