Non-Assignable Expression

error in component $compile

This error occurs when a directive defines an isolate scope property that support two-way data-binding (using the = mode in the directive definition) but the directive is used with an expression that is not-assignable.

In order for the two-way data-binding to work, it must be possible to write new values back into the path defined with the expression.

For example, given a directive:

myModule.directive('myDirective', function factory() {
  return {
    ...
    scope: {
      'bind': '=localValue'
    }
    ...
  }
});

Following are invalid uses of this directive:

<my-directive bind="1+2">    <!-- ERROR because `1+2=localValue` is an invalid statement -->
<my-directive bind="myFn()"> <!-- ERROR because `myFn()=localValue` is an invalid statement -->

To resolve this error, always use path expressions with scope properties that are two-way data-bound:

<my-directive bind="some.property">
<my-directive bind="some[3]['property']">