How to solve Vue error: Unable to correctly use ref to access parent component instance in child component

How to solve the Vue error: Unable to correctly use ref to access the parent component instance in the child component

In Vue development, communication between parent and child components is very common operate. One of the common ways is to use ref to access the instance of the parent component in the child component. However, sometimes you will encounter an error: ref cannot be used correctly to access the parent component instance in the child component. This article will introduce the cause of this error and provide solutions and code examples.

Problem analysis:
When we use ref in a child component to refer to a parent component instance, sometimes the error "Cannot read property '$parent' of undefined" will appear. The reason for this error is that during the creation process of the child component, the parent component instance has not been completely created, causing the child component to be unable to correctly access the parent component instance.

Solution:
In order to solve this problem, we need to access the parent component instance at the appropriate time. Vue provides a life cycle hook function to handle this situation, namely "mounted". We can access the parent component instance in the mounted hook function of the child component to ensure that the parent component has been fully created.

The sample code is as follows:

// Parent component