Extract rule: template-no-builtin-form-components

README.md

@@ -211,6 +211,7 @@ rules in templates can be disabled with eslint directives with mustache or html
 | [template-no-bare-strings](docs/rules/template-no-bare-strings.md)                                           | disallow bare strings in templates (require translation/localization)        |    |    |    |
 | [template-no-bare-yield](docs/rules/template-no-bare-yield.md)                                               | disallow templates whose only meaningful content is a bare {{yield}}         |    |    |    |
 | [template-no-block-params-for-html-elements](docs/rules/template-no-block-params-for-html-elements.md)       | disallow block params on HTML elements                                       |    |    |    |
+| [template-no-builtin-form-components](docs/rules/template-no-builtin-form-components.md)                     | disallow usage of built-in form components                                   |    |    |    |
 | [template-no-capital-arguments](docs/rules/template-no-capital-arguments.md)                                 | disallow capital arguments (use lowercase @arg instead of @Arg)              |    |    |    |
 | [template-no-chained-this](docs/rules/template-no-chained-this.md)                                           | disallow redundant `this.this` in templates                                  |    | 🔧 |    |
 | [template-no-class-bindings](docs/rules/template-no-class-bindings.md)                                       | disallow passing classBinding or classNameBindings as arguments in templates |    |    |    |

docs/rules/template-no-builtin-form-components.md

@@ -0,0 +1,90 @@
+# ember/template-no-builtin-form-components
+
+<!-- end auto-generated rule header -->
+
+Disallow usage of Ember's built-in `<Input>` and `<Textarea>` components. These components use two-way binding to mutate values, which is considered an anti-pattern. Use native HTML `<input>` and `<textarea>` elements instead.
+
+## Examples
+
+This rule **forbids** the following:
+
+```gjs
+<template><Input @type="text" @value={{this.name}} /></template>
+```
+
+```gjs
+<template><Textarea @value={{this.body}}></Textarea></template>
+```
+
+This rule **allows** the following:
+
+```gjs
+<template><input type="text" value={{this.name}} {{on "input" this.handleInput}} /></template>
+```
+
+```gjs
+<template><textarea {{on "input" this.handleInput}}>{{this.body}}</textarea></template>
+```
+
+## Migration
+
+Many forms may be simplified by switching to a light one-way data approach.
+
+For example – vanilla JavaScript has everything we need to handle form data, de-sync it from our source data and collect all user input in a single object.
+
+```js
+import Component from '@glimmer/component';
+import { tracked } from '@glimmer/tracking';
+import { action } from '@ember/object';
+
+export default class MyComponent extends Component {
+  @tracked userInput = {};
+
+  @action
+  handleInput(event) {
+    const formData = new FormData(event.currentTarget);
+    this.userInput = Object.fromEntries(formData.entries());
+  }
+}
+```
+
+```hbs
+<form {{on 'input' this.handleInput}}>
+  <label>
+    Name
+    <input name='name' />
+  </label>
+</form>
+```
+
+Another option would is to "control" the field's value by replacing the built-in form component with a native HTML element and binding an event listener to handle user input.
+
+In the following example the initial value of a field is controlled by a local tracked property, which is updated by an event listener.
+
+```js
+import Component from '@glimmer/component';
+import { tracked } from '@glimmer/tracking';
+import { action } from '@ember/object';
+
+export default class MyComponent extends Component {
+  @tracked name;
+
+  @action
+  updateName(event) {
+    this.name = event.target.value;
+  }
+}
+```
+
+```hbs
+<input type='text' value={{this.name}} {{on 'input' this.updateName}} />
+```
+
+## Related Rules
+
+- [no-mut-helper](template-no-mut-helper.md)
+
+## References
+
+- [Ember Built-in Components](https://guides.emberjs.com/release/components/built-in-components/)
+- [ember-template-lint no-builtin-form-components](https://github.com/ember-template-lint/ember-template-lint/blob/master/docs/rule/no-builtin-form-components.md)

lib/rules/template-no-builtin-form-components.js

@@ -0,0 +1,88 @@
+/** @type {import('eslint').Rule.RuleModule} */
+module.exports = {
+  meta: {
+    type: 'problem',
+    docs: {
+      description: 'disallow usage of built-in form components',
+      category: 'Best Practices',
+      url: 'https://github.com/ember-cli/eslint-plugin-ember/tree/master/docs/rules/template-no-builtin-form-components.md',
+      templateMode: 'both',
+    },
+    fixable: null,
+    schema: [],
+    messages: {
+      noInput:
+        'Do not use the `Input` component. Built-in form components use two-way binding to mutate values. Instead, refactor to use a native HTML element.',
+      noTextarea:
+        'Do not use the `Textarea` component. Built-in form components use two-way binding to mutate values. Instead, refactor to use a native HTML element.',
+    },
+    originallyFrom: {
+      name: 'ember-template-lint',
+      rule: 'lib/rules/no-builtin-form-components.js',
+      docs: 'docs/rule/no-builtin-form-components.md',
+      tests: 'test/unit/rules/no-builtin-form-components-test.js',
+    },
+  },
+
+  create(context) {
+    const MESSAGE_IDS = {
+      Input: 'noInput',
+      Textarea: 'noTextarea',
+    };
+
+    const filename = context.filename ?? context.getFilename();
+    const isStrictMode = filename.endsWith('.gjs') || filename.endsWith('.gts');
+
+    // local name → original name ('Input' | 'Textarea')
+    // Only populated in GJS/GTS files via ImportDeclaration
+    const importedComponents = new Map();
+
+    return {
+      ImportDeclaration(node) {
+        if (node.source.value === '@ember/component') {
+          for (const specifier of node.specifiers) {
+            if (specifier.type === 'ImportSpecifier') {
+              const original = specifier.imported.name;
+              if (original === 'Input' || original === 'Textarea') {
+                importedComponents.set(specifier.local.name, original);
+              }
+            }
+          }
+        }
+      },
+
+      GlimmerElementNode(node) {
+        const tag = node.tag;
+        if (isStrictMode) {
+          // In GJS/GTS: only flag if explicitly imported from @ember/component
+          const original = importedComponents.get(tag);
+          if (original) {
+            context.report({ node, messageId: MESSAGE_IDS[original] });
+          }
+        } else {
+          // In HBS: flag by canonical name (no import context available)
+          const messageId = MESSAGE_IDS[tag];
+          if (messageId) {
+            context.report({ node, messageId });
+          }
+        }
+      },
+
+      // Catch usages as a value: {{yield Input}}, (component Input), @field={{Input}}, etc.
+      GlimmerPathExpression(node) {
+        const name = node.original;
+        if (isStrictMode) {
+          const original = importedComponents.get(name);
+          if (original) {
+            context.report({ node, messageId: MESSAGE_IDS[original] });
+          }
+        } else {
+          const messageId = MESSAGE_IDS[name];
+          if (messageId) {
+            context.report({ node, messageId });
+          }
+        }
+      },
+    };
+  },
+};

tests/lib/rules/template-no-builtin-form-components.js

@@ -0,0 +1,165 @@
+const rule = require('../../../lib/rules/template-no-builtin-form-components');
+const RuleTester = require('eslint').RuleTester;
+
+const ruleTester = new RuleTester({
+  parser: require.resolve('ember-eslint-parser'),
+  parserOptions: { ecmaVersion: 2022, sourceType: 'module' },
+});
+
+ruleTester.run('template-no-builtin-form-components', rule, {
+  valid: [
+    // Native HTML elements are always fine
+    { filename: 'test.gjs', code: '<template><input type="text" /></template>' },
+    { filename: 'test.gjs', code: '<template><input type="checkbox" /></template>' },
+    { filename: 'test.gjs', code: '<template><input type="radio" /></template>' },
+    { filename: 'test.gjs', code: '<template><textarea></textarea></template>' },
+    { filename: 'test.gjs', code: '<template><div></div></template>' },
+
+    // In GJS without an import from @ember/component, <Input>/<Textarea> are not the builtins
+    { filename: 'test.gjs', code: '<template><Input /></template>' },
+    { filename: 'test.gjs', code: '<template><Textarea></Textarea></template>' },
+
+    // Importing from a different source is fine
+    {
+      filename: 'test.gjs',
+      code: "import { Input } from './my-components'; <template><Input /></template>",
+    },
+    {
+      filename: 'test.gjs',
+      code: "import { Textarea } from './my-components'; <template><Textarea></Textarea></template>",
+    },
+  ],
+  invalid: [
+    {
+      filename: 'test.gjs',
+      code: "import { Input } from '@ember/component'; <template><Input /></template>",
+      output: null,
+      errors: [{ messageId: 'noInput' }],
+    },
+    {
+      filename: 'test.gjs',
+      code: 'import { Input } from \'@ember/component\'; <template><Input type="text" /></template>',
+      output: null,
+      errors: [{ messageId: 'noInput' }],
+    },
+    {
+      // Aliased import must still be flagged
+      filename: 'test.gjs',
+      code: "import { Input as EmberInput } from '@ember/component'; <template><EmberInput /></template>",
+      output: null,
+      errors: [{ messageId: 'noInput' }],
+    },
+    {
+      filename: 'test.gjs',
+      code: "import { Textarea } from '@ember/component'; <template><Textarea></Textarea></template>",
+      output: null,
+      errors: [{ messageId: 'noTextarea' }],
+    },
+    {
+      filename: 'test.gjs',
+      code: "import { Textarea } from '@ember/component'; <template><Textarea @value={{this.body}}></Textarea></template>",
+      output: null,
+      errors: [{ messageId: 'noTextarea' }],
+    },
+    {
+      // Aliased Textarea import must still be flagged
+      filename: 'test.gjs',
+      code: "import { Textarea as EmberTextarea } from '@ember/component'; <template><EmberTextarea></EmberTextarea></template>",
+      output: null,
+      errors: [{ messageId: 'noTextarea' }],
+    },
+    // Yielded as a value
+    {
+      filename: 'test.gjs',
+      code: "import { Input } from '@ember/component'; <template>{{yield Input}}</template>",
+      output: null,
+      errors: [{ messageId: 'noInput' }],
+    },
+    {
+      filename: 'test.gjs',
+      code: "import { Input as EmberInput } from '@ember/component'; <template>{{yield EmberInput}}</template>",
+      output: null,
+      errors: [{ messageId: 'noInput' }],
+    },
+    {
+      filename: 'test.gjs',
+      code: "import { Textarea } from '@ember/component'; <template>{{yield Textarea}}</template>",
+      output: null,
+      errors: [{ messageId: 'noTextarea' }],
+    },
+    // Used in helpers / passed as argument
+    {
+      filename: 'test.gjs',
+      code: "import { Input } from '@ember/component'; <template><MyForm @field={{Input}} /></template>",
+      output: null,
+      errors: [{ messageId: 'noInput' }],
+    },
+    {
+      filename: 'test.gjs',
+      code: "import { Input } from '@ember/component'; <template>{{component Input}}</template>",
+      output: null,
+      errors: [{ messageId: 'noInput' }],
+    },
+  ],
+});
+
+const hbsRuleTester = new RuleTester({
+  parser: require.resolve('ember-eslint-parser/hbs'),
+  parserOptions: {
+    ecmaVersion: 2022,
+    sourceType: 'module',
+  },
+});
+
+hbsRuleTester.run('template-no-builtin-form-components (hbs)', rule, {
+  valid: [
+    '<input type="text" />',
+    '<input type="checkbox" />',
+    '<input type="radio" />',
+    '<textarea></textarea>',
+  ],
+  invalid: [
+    {
+      code: '<Input />',
+      output: null,
+      errors: [{ messageId: 'noInput' }],
+    },
+    {
+      code: '<Input type="text" />',
+      output: null,
+      errors: [{ messageId: 'noInput' }],
+    },
+    {
+      code: '<Textarea></Textarea>',
+      output: null,
+      errors: [{ messageId: 'noTextarea' }],
+    },
+    {
+      code: '<Textarea @value={{this.body}}></Textarea>',
+      output: null,
+      errors: [{ messageId: 'noTextarea' }],
+    },
+    // Yielded as a value
+    {
+      code: '{{yield Input}}',
+      output: null,
+      errors: [{ messageId: 'noInput' }],
+    },
+    {
+      code: '{{yield Textarea}}',
+      output: null,
+      errors: [{ messageId: 'noTextarea' }],
+    },
+    // Used in helpers / passed as argument
+    {
+      code: '<MyForm @field={{Input}} />',
+      output: null,
+      errors: [{ messageId: 'noInput' }],
+    },
+    {
+      code: '{{component Input}}',
+      output: null,
+      errors: [{ messageId: 'noInput' }],
+    },
+  ],
+});