AUR0151

Error Message

AUR0151: No binding behavior definition found for type <TypeName>

Where <TypeName> is the name of the class associated with the binding behavior.

Description

This error occurs when Aurelia attempts to resolve a binding behavior resource (e.g., used in a binding expression like myProp & myBehavior) but cannot find the associated definition metadata for the specified type (class). Binding behavior definitions are typically created using the @bindingBehavior decorator or by following naming conventions recognized by Aurelia.

Cause

Common causes for this error include:

1. Missing Decorator or Convention: The class intended to be a binding behavior is missing the @bindingBehavior('behavior-name') decorator, and it doesn't follow a recognized naming convention (like MyBehaviorBindingBehavior).

2. Incorrect Registration: The binding behavior class was defined but not correctly registered with the Aurelia container, either globally (Aurelia.register(...)) or locally within a component's dependencies array.

3. Build/Packaging Issues: The build process might not be correctly including or processing the binding behavior file, or there might be issues with module resolution.

4. Typo in Class Name: The class name provided during registration or inferred by convention might have a typo.

Solution

1. Add Decorator/Follow Convention: Ensure your binding behavior class has the @bindingBehavior('behavior-name') decorator applied, or that it follows the *BindingBehavior naming convention.

2. Register the Behavior: Verify that the binding behavior is registered correctly.

   • Global Registration: Use Aurelia.register(MyBindingBehavior) in your main application setup (main.ts or similar).

   • Local Registration: Add the binding behavior class to the dependencies array of the component's dependencies array.

3. Check Build Configuration: Ensure your build setup (e.g., Webpack, Vite) is configured to correctly process and bundle Aurelia resources, including decorators and conventions. Verify module imports and exports.

4. Verify Class Name: Double-check the spelling of the binding behavior class name in its definition and registration.

Example

// my-behavior.ts
import { bindingBehavior } from 'aurelia';

// Correct: Using the decorator
@bindingBehavior('myBehavior')
export class MyBehavior {
  // Behavior logic...
}

// Incorrect: Missing decorator and doesn't follow convention
// export class MyBehavior { /* ... */ } // This would likely cause AUR0151 if used

// --- main.ts or component definition ---
import { Aurelia } from 'aurelia';
import { MyBehavior } from './my-behavior';
// import { MyComponent } from './my-component'; // If registering locally

// Global Registration:
// Aurelia.register(MyBehavior) /* ... */;

// Local Registration (in my-component.ts):
// @customElement({
//   name: 'my-component',
//   template: `<input value.bind="message & myBehavior">`,
//   dependencies: [MyBehavior] // Register locally
// })
// export class MyComponent { message = 'Hello'; }

Debugging Tips

• Verify the exact name (<TypeName>) mentioned in the error message matches the intended class name.

• Search your codebase for the binding behavior's class name and decorator (@bindingBehavior) to ensure it's defined correctly.

• Check your main.ts (or equivalent startup file) for global registrations.

• Check the dependencies array of the component(s) where the binding behavior is used.

• Inspect the build output or use browser developer tools to see if the binding behavior module is loaded correctly.

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