Readonly Property

Cannot Assign To Read-Only Property

What happened?

A read-only property was written.

Why is this bad?

The QML engine will throw a Type Error when it sees the write to a read-only property.

Example

 import QtQuick

 Item {
     id: root
     readonly property int someNumber: 10

     Component.onCompleted: {
         someNumber = 20  // not ok: TypeError: Cannot assign to read-only property
     }
 }

You can fix this warning by removing the write to the read-only property, by writing to another non-read-only property, or by removing the readonly modifier if the property should no longer be considered constant.

See also Read-Only Properties.