How to implement polling request data in vue

In Web development, polling request data is a very common technical method, which can continuously send requests to the back-end service in order to obtain new data or status information. In the Vue framework, polling request data can be implemented through some simple technical means. This article will introduce how to use the Vue framework to implement polling request data.

1. Use the watch attribute of Vue

The watch attribute in Vue is used to monitor changes in certain data and perform corresponding operations. We can use the watch attribute to implement the function of polling request data. The specific implementation steps are as follows:

1. Declare a value in the Vue component to store the data that needs to be polled, for example:

data() {
  return {
    data: null // 需要轮询的数据
  }
}

2. Next, we need to use the mounted life cycle function Create a watcher to monitor changes in data attributes and perform corresponding operations. In the watcher, we use the setInterval function to send data requests regularly. For example:

mounted() {
  const pollData = setInterval(() => {
    axios.get('yourapi').then(response => {
      this.data = response.data // 将获取的数据赋值给data属性
    }).catch(error => console.log(error))
  }, 5000) // 设置定时器的时间间隔为5s
  // 组件销毁时清除定时器
  this.$once('hook:beforeDestroy', () => {
    clearInterval(pollData)
  })
}

In the above code, we use the axios library to send data requests and assign the data returned by axios to the data attribute. By setting the timer interval to 5 seconds, you can send requests to the backend service regularly.

In addition, we also need to clear the timer when the component is destroyed to avoid memory leaks. In Vue, you can use the $once function to monitor the component's hook:beforeDestroy life cycle to perform some necessary cleanup operations before the component is destroyed, such as clearing the timer.

Using Vue's watch attribute to implement polling for request data is very simple, but it should be noted that this method is not reliable in some cases. For example, if the network speed is poor or the backend service responds slowly, it may cause consecutive requests to overlap, resulting in data duplication or status errors. Therefore, we need to use more rigorous methods to solve this problem.

2. Use Vue-style RxJS

RxJS is a powerful reactive programming library that provides a powerful API to handle asynchronous events. In Vue, we can use Vue-style RxJS to implement the function of polling request data. The specific implementation steps are as follows:

1. First, we need to introduce the Vue-style RxJS library, for example:

import VueRx from 'vue-rx'
Vue.use(VueRx)

Here we use Vue’s use function to introduce RxJS.

2. Next, use the interval function of RxJS in the component to create a timer, for example:

mounted() {
  const pollData = this.$interval(5000) // 设置定时器的时间间隔为5s
  // 组件销毁时清除定时器
  this.$once('hook:beforeDestroy', () => {
    pollData.unsubscribe()
  })
}

In the above code, we use the $interval function of Vue to create A timer. The $interval function is similar to the RxJS interval function. It periodically sends data requests to the backend service and returns an Observable object.

Observable is a key concept in RxJS, which represents an asynchronous event stream that can be subscribed to. In the above code, we create an Observable object and unsubscribe it when the component is destroyed.

3. Next, we use the combineLatest function to combine Observable objects and map them into a new object. For example:

mounted() {
  const pollData = this.$interval(5000) // 设置定时器的时间间隔为5s
  // 组合Observable对象
  const getData = this.$http.get('yourapi') // 发送数据请求
  const combined = this.$observables.combineLatest(pollData, getData)
  
  combined.subscribe(([_, response]) => {
    this.data = response.data // 将获取的数据赋值给data属性
  }, error => console.log(error))
  // 组件销毁时清除定时器
  this.$once('hook:beforeDestroy', () => {
    pollData.unsubscribe()
  })
}

In the above code, we use Vue's $http object to send data requests, and use the combineLatest function to combine two Observable objects. When subscribing to the Observable object, we use array destructuring to obtain the value of the second element in the returned array (that is, the data returned by the request) and assign it to the data attribute.

The method of using Vue-style RxJS to implement polling request data is more complicated, but it can avoid the overlapping problem between request and response. At the same time, RxJS also provides a rich API and operators that can help us better handle asynchronous events.

Summary

The method of using Vue to implement polling request data is very simple. We can use Vue's watch attribute or RxJS to implement it. Both methods have their own advantages and disadvantages, and they need to be chosen according to the actual situation. At the same time, we also need to pay attention to some common problems, such as memory leaks and overlap between request and response. By carefully handling these issues, we can implement efficient and reliable polling for requested data.

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