angular.js - Directive interaction problem, dependent directive not found

Question

I call APPLeft within the appContent directive. Prompt this error: Controller 'appLeft', required by directive 'appContent', can't be found!

Why does appLeft prompt this

Answer 1

I found the answer on stackoverflow. You must put app-content in app-left to use it this way, that is:

<app-left>
    <app-content></app-content>
</app-left>