AUR0102

Error Message

AUR0102: Ast eval error: binding behavior "<behavior_name>" already applied.

Where <behavior_name> is the name of the binding behavior applied multiple times.

Description

This error occurs when the same binding behavior (e.g., debounce, throttle) is applied more than once to a single binding expression in the template. Each behavior should only be applied once per expression.

Cause

The most common causes are:

1. Accidental Repetition: Simply typing the same binding behavior twice in the expression (e.g., value & debounce & debounce).

2. Redundant Behaviors: Applying two different binding behaviors that serve mutually exclusive purposes on the same binding (e.g., applying both throttle and debounce might be illogical and could potentially lead to this or other errors depending on internal implementation, although this specific error checks for identical behavior names).

Solution

Review the binding expression identified in the error message and remove the duplicate binding behavior application. Ensure that each desired behavior is listed only once using the & syntax.

Example

<!-- Incorrect: 'debounce' is applied twice -->
<input value.bind="searchTerm & debounce:500 & debounce:500">

<!-- Incorrect: 'throttle' is applied twice -->
<div mousemove.trigger="handleMouseMove($event) & throttle:100 & throttle:100"></div>

<!-- Correct: Apply each behavior only once -->
<input value.bind="searchTerm & debounce:500">
<div mousemove.trigger="handleMouseMove($event) & throttle:100"></div>

<!-- Example with multiple *different* behaviors (Correct) -->
<input value.bind="searchTerm & debounce:500 & updateTrigger:'blur'">

Debugging Tips

• Carefully read the binding expression in your template where the error is reported.

• Look for repeated & behaviorName segments.

• Ensure you haven't accidentally copied and pasted parts of the binding expression leading to duplication.