Multiple Uncaught Errors Using the react-rails Gem

Question

To preface my question, I am following this guide.

When trying to build a CRUD interface using Rails and React, I receive this error when trying to create a new item:

addComponentAsRefTo(...): Only a ReactOwner can have refs. You might be adding a ref to a component that was not created inside a component's render method, or you have multiple copies of React loaded.

I wasn't improperly adding a ref attribute to any JSX not inside of a render method, so I must have multiple copies of React within my asset pipeline.

Research yielded the following potential results:

1. Introducing webpack or Searchkit, suggested in this SO answer, seemed to be clunky workarounds for my simple CRUD interface.
2. This unselected SO answer suggested removing the //= require react line from ./app/assets/javascripts/application.js. This proved to be unsuccessful.
3. Issue #671, from the official GitHub react-rails repo. here, outlines the first part of my issue perfectly. I followed this potential solution, which suggests removing the //= require react-server line of the ./app/assets/javascripts/server_rendering.js file. This lead to a new error, outlined below:

Uncaught ReferenceError: $ is not defined

Which I assume means that react_server not only contains a second copy of React, but also loads something vital for my AJAX calls.

For reference, here are the contents of ./app/assets/javascripts/application.js:

// This is a manifest file that'll be compiled into application.js, which will include all the files
...
// about supported directives.
//
//= require rails-ujs
//= require react
//= require components
//= require turbolinks
//= require_tree .

and ./app/assets/javascripts/server_rendering.js:

//= require react_ujs
//= require react-server
//= require ./components
...

Where a set of ellipses, or ..., are used to shorten known comment sections.

• Ruby version: 2.3.3p222 (2016-11-21 revision 56859)
• Rails version: 5.1.1
• react-rails version: 2.2.0

Answer 1

The third potential answer, or removing the //= require react-server from ./app/assets/javascripts/server_rendering.js, was a step in the right direction.

Removing this line doesn't yield a new issue, it just reveals another error you had the entire time. react_server doesn't define the $ variable for AJAX calls, the jQuery gem does.

Found here. I am confident in this solution because the error:

Uncaught ReferenceError: $ is not defined

is a jQuery issue, as the AJAX calls you are probably making take a form referenced in their official doc. here.

Therefore, after running gem install jquery-rails in your shell, your ./app/assets/javascripts/application.js should look like this:

...
//= require rails-ujs
//= require jquery
//= require react
//= require components
//= require turbolinks
//= require_tree .

Your ./app/assets/javascripts/server_rendering.js file should look like this:

//= require react_ujs
// require react-server
//= require ./components
...

Note that require react-server is commented out.

And make sure to follow the solution found in this SO answer regarding the .\app\views\layouts\application.html.erb file.