# AUR0754

## Error Message

`AUR0754: Attribute <attribute-name> is not registered in <component-name>.`

Where `<attribute-name>` is the name of the template controller attribute used (e.g., `if`, `repeat`), and `<component-name>` is the name of the component whose template is being rendered.

## Description

This error occurs during rendering when Aurelia encounters a template controller attribute (e.g., `<div if.bind="condition">`, `<div repeat.for="item of items">`), but it cannot find the definition for that specific template controller within the resources registered for the current component or globally.

## Cause

While the built-in template controllers (`if`, `else`, `repeat.for`, `switch`, `case`, `default-case`, `promise.resolve`, `pending`, `then`, `catch`, `portal`) are usually available by default when using the `StandardConfiguration` or `DefaultComponents`, this error can still occur if:

1. **Minimal Configuration:** You are using a minimal Aurelia configuration (e.g., `Aurelia.register()`) that does not include the standard template controllers, and you haven't registered them manually.
2. **Custom Template Controller Issues:**
   * **Missing Import:** A custom template controller class was not imported.
   * **Missing `dependencies`:** The imported custom template controller was not added to the `dependencies` array.
   * **Typo:** The name used in the template (e.g., `my-repeater.for`) doesn't match the registered name.
   * **Incorrect Registration:** A custom template controller wasn't registered correctly.
3. **Build/Bundling Issues:** The necessary template controller definitions (standard or custom) are not being included in the final build.

## Solution

1. **Use Standard Configuration:** Ensure you are registering the `StandardConfiguration` or `DefaultComponents` when bootstrapping Aurelia if you intend to use the built-in template controllers.

   ```typescript
   import Aurelia, { StandardConfiguration } from 'aurelia';

   Aurelia
     .register(StandardConfiguration) // Includes default template controllers
     .app(MyApp)
     .start();
   ```
2. **Register Manually (Minimal Config):** If using a minimal setup, explicitly register the template controllers you need.

   ```typescript
   import Aurelia from 'aurelia';
   import { IfRegistration, RepeatRegistration } from '@aurelia/runtime-html'; // Example imports

   Aurelia
     .register(
       IfRegistration, // Register 'if' and 'else'
       RepeatRegistration // Register 'repeat.for'
       // ... other needed registrations
     )
     .app(MyApp)
     .start();
   ```
3. **For Custom Template Controllers:**
   * **Import:** Import the controller class.
   * **Add to Dependencies:** Include it in the `dependencies` array of the component using it.
   * **Verify Name:** Check the name in the template against its definition.
   * **Check Registration:** Ensure correct local or global registration.
4. **Verify Build:** Check the build/bundler configuration.

## Debugging Tips

* Confirm which configuration preset (`StandardConfiguration`, etc.) you are using during bootstrap.
* If using a minimal configuration, verify that all necessary template controllers (built-in or custom) are explicitly registered.
* For custom template controllers, follow the same debugging steps as for custom elements (AUR0752) and attributes (AUR0753): check imports, dependencies, names, and build output.


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