ember-angle-brackets-codemod

A jscodeshift Codemod to convert curly braces syntax to angle brackets syntax for templates in an Ember.js app

Refer to this RFC for more details on Angle brackets invocation syntax.

Usage

WARNING: jscodeshift, and thus this codemod, edits your files in place. It does not make a copy. Make sure your code is checked into a source control repository like Git and that you have no outstanding changes to commit before running this tool.

$ cd my-ember-app-or-addon
$ npx ember-angle-brackets-codemod angle-brackets app/templates

From

{{site-header user=this.user class=(if this.user.isAdmin "admin")}}

{{#super-select selected=this.user.country as |s|}}
  {{#each this.availableCountries as |country|}}
    {{#s.option value=country}}{{country.name}}{{/s.option}}
  {{/each}}
{{/super-select}}

{{ui/button text="Click me"}}

To

<SiteHeader @user={{this.user}} class={{if this.user.isAdmin "admin"}} />
<SuperSelect @selected={{this.user.country}} as |s|>
  {{#each this.availableCountries as |country|}}
    <s.option @value={{country}}>
      {{country.name}}
    </s.option>
  {{/each}}
</SuperSelect>

<Ui::Button @text="Click me" />

Advanced Usage

Skipping helpers

To help the codemod disambiguate components and helpers, you can define a list of helpers from your application in a configuration file as follows:

config/anglebrackets-codemod-config.json

{
  "helpers": [
    "date-formatter", 
    "info-pill"
  ]
}

The codemod will then ignore the above list of helpers and prevent them from being transformed into the new angle-brackets syntax.

You can also disable the conversion of the built-in components {{link-to}}, {{input}} and {{textarea}} as follows:

config/anglebrackets-codemod-config.json

{
  "helpers": [],
  "skipBuiltInComponents": true
}

You can execute the codemod with custom configuration by specifying a --config command line option as follows:

$ cd my-ember-app-or-addon
$ npx ember-angle-brackets-codemod angle-brackets app/templates --config ./config/anglebrackets-codemod-config.json

To get a list of helpers in your app you can do this in the Developer Console in your browser inside of your app:

var componentLikeHelpers = Object.keys(require.entries)
    .filter(name=>(name.includes('/helpers/')|| name.includes('/helper')))
    .filter(name=>!name.includes('/-')).map(name=>{
        let path = name.split('/helpers/');
        return path.pop();
    }).filter(name=>!name.includes('/')).uniq();

copy(JSON.stringify(componentLikeHelpers))

Skipping some files

If there are files that don't convert well, you can skip them by specifying an optional skipFilesThatMatchRegex configuration setting. For example, with the configuration below, all files that contain "foo" or "bar" will be skipped:

config/anglebrackets-codemod-config.json

{
  "helpers": [],
  "skipBuiltInComponents": true,
  "skipFilesThatMatchRegex": "foo|bar"
}

Debugging Workflow

Oftentimes, you want to debug the codemod or the transform to identify issues with the code or to understand how the transforms are working, or to troubleshoot why some tests are failing.

Hence we recommend a debugging work-flow like below to quickly find out what is causing the issue.

1. Place debugger statements

Add debugger statements, in appropriate places in the code. For example:

...
const params = a.value.params.map(p => {
  debugger;
  if(p.type === "SubExpression") {
    return transformNestedSubExpression(p)
...

2. Inspect the process with node debug

Here we are going to start the tests selectively in node debug mode. Since the codemod is bootstrapped using codemod-cli which is using jest in turn to run the tests, jest is having an option -t <name-of-spec> to run a particular set of tests instead of running the whole test suite.

We are making use of both these features to start our tests in this particular fashion. For more details on node debug, visit the official Node.js debugging guide, and for jest documentation on tests, please refer here.

node --inspect-brk ./node_modules/.bin/codemod-cli -t '<fixture-name>'

For example, if you want to debug the null-subexp.input.hbs fixture or only that particular test case is failing because of an issue.

node --inspect-brk ./node_modules/.bin/codemod-cli -t 'null-subexp'

Once you run the above command, your tests will start running in debug mode and your breakpoints will be triggered appropriately when that particular block of code gets executed. You can run the debugger inside Chrome browser dev-tools. More details on here

AST Explorer playground

1. Go to the AST Explorer
2. Paste your curly brace syntax code in the top left corner window (Source)
3. You will get the converted angle bracket syntax in the bottom right corner window (Transform Output)

RFC

• Angle Bracket Invocation
• Angle Bracket Invocations For Built-in Components

Known issues

• No formatting preserved

References:

• glimmerjs/glimmer-vm#685
• https://github.com/q2ebanking/ember-template-rewrite
• https://github.com/ember-template-lint/ember-template-recast