What should I do if the uniapp template data is not updated?

Recently, I was using uniapp to develop a small program and encountered a strange problem: the template data was not updated. After the data is modified, the data on the page is not updated in time, resulting in a poor user experience. After some investigation, I found a solution to this problem, and now I would like to share my experience with you.

First, we need to understand the data binding mechanism of uniapp. In uniapp, data binding uses the template syntax of the Vue.js framework, and double curly braces are used to bind variables in the template. When the data changes, Vue.js will automatically update the DOM page to achieve real-time updates of the data.

So, why is my data not updated? After some investigation, I found that I had made a low-level mistake: after modifying the data, I did not call the update method provided by uniapp, resulting in the page not updating the data immediately.

uniapp provides two methods for updating data:

1. $nextTick(callback)

$nextTick(callback) is provided by the Vue.js framework method, in the life cycle of Vue.js, when the data changes, the DOM page will not be updated immediately. Vue.js will update the DOM page in the next Event Loop cycle. The $nextTick(callback) method will execute the callback function after the DOM is updated, which can ensure that the relevant operations are performed after the data is updated.

In uniapp, we can call the $nextTick method through this.$nextTick(callback). The sample code is as follows:

this.dataList.push(newData) //修改数据
this.$nextTick(() => {
  //数据更新后执行的相关操作
})

2. this.$set(object, propertyName, value )

this.$set() is a method provided by uniapp for updating data. When we modify a property in an object, Vue.js will not detect the change, causing the data to not be updated. At this time, we can call this.$set() method to tell Vue.js about this change, thereby updating the data.

In uniapp, we can call the $this.$set() method through this.$set(object, propertyName, value). The sample code is as follows:

this.$set(this.dataList, index, newData) //修改数据

The above code means that The index item in the dataList array is modified to newData.

Finally, we need to pay attention to one detail: in uniapp, the reference relationship of template data has an impact on data updates. If the data reference relationship in the template is disconnected, the data will not be updated in real time. Therefore, when modifying data, we should try to keep the data reference relationship unchanged. If you need to modify the data reference relationship, you need to use the this.$set() method to notify Vue.js of data changes.

Through the above methods, we can solve the problem of uniapp template data not being updated and improve the user experience of the mini program. However, I also realize that the quality of my code needs to be improved, and I must pay attention to details and try to avoid low-level errors.

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