Vue and Element-UI cascaded drop-down box remote search

The key to the efficient remote search cascading selection box is: a reasonable request strategy: load data on demand, avoid loading all data at once. Data processing: The data structure returned by the backend should be standardized, and error handling and loading status prompts should be done well. Performance optimization: Consider paging, caching and code optimization to improve loading efficiency.

Remote search of Vue and Element-UI cascaded drop-down boxes: Do you really understand?

Many students will encounter the situation where the cascading selection box needs to remotely search for data when using Vue and Element-UI for projects. This seems simple, but in fact it has hidden mystery. If you are not careful, you will fall into the pit. The performance is worrying and the user experience is extremely poor. In this article, let’s talk about this thing. It not only teaches you how to do it, but more importantly, teaches you why you do it, and the pitfalls you may have stepped on.

Let’s talk about the conclusion first: The key to efficient remote search cascade selection boxes is to make reasonable request strategies and data processing. Don't just ask for everything, it's a disaster.

Basic knowledge laying the groundwork: You need to know this

Let's first review the basic knowledge of Vue and Element-UI. Vue's data-driven view, Element-UI provides ready-made components, we just need to combine them cleverly. The key is to understand the load properties of the el-cascader component of Element-UI, which is the key to remotely loading data. In addition, you must be familiar with asynchronous programming (Promise or async/await), otherwise it will be painful to handle remote requests.

Core: The essence of remote loading

load property of el-cascader accepts a function that will be called when the selection box is expanded or when the node is selected. This function needs to initiate a request to the backend based on the currently selected node to obtain the next level of data. The key is: don't load all the data in one go! Imagine how bad the user experience would be if your data is large and you load all the data every time!

Therefore, we need to load data on demand based on user's choice. For example, if the user selects a province, then loads all cities under the province; if the user selects a city, then loads all districts and counties under the city. This is an efficient remote search strategy.

Code example: Practice to create true knowledge

The following is an example, using async/await to handle asynchronous requests. The code style is relatively concise and has strong readability:

 <code class="javascript"><el-cascader v-model="selectedOptions" :props="props" :load="loadOptions" placeholder="请选择"> </el-cascader> <script> export default { data() { return { selectedOptions: [], props: { label: &#39;label&#39;, value: &#39;value&#39;, children: &#39;children&#39; } }; }, methods: { async loadOptions(node, resolve) { const { value } = node; // 模拟远程请求，用setTimeout模拟网络延迟await new Promise(resolve => setTimeout(resolve, 500)); const data = await this.fetchOptions(value); resolve(data); }, async fetchOptions(parentId) { // 这里替换成你的实际请求逻辑，例如使用axios const response = await this.$axios.get(`/api/options?parentId=${parentId}`); return response.data; }, handleChange(value) { console.log(value); } } }; </script></code>

Advanced usage: anti-shake and throttling

If your search box supports input keyword search, then you need to consider anti-shake and throttling techniques. When users enter quickly, frequent requests will put huge pressure on the server and even cause the interface to time out. Anti-shake and throttling can effectively reduce the number of requests and improve performance. The Lodash library provides debounce and throttle functions, which can easily achieve anti-shake and throttling.

Guide to the pitfalls: Avoid these errors

• The data structure is not standardized: the data structure returned by the backend must be standardized and match the props configuration of el-cascader . Otherwise, the rendering will go wrong.
• Error handling: Network requests may fail. You need to deal with various error situations, such as network errors, server errors, etc., and give user-friendly prompts.
• Loading status: When loading data, the user should be given a prompt while loading to avoid the user being overwhelmed for a long time.

Performance optimization: Let it fly

• Paging: If the amount of data is very large, you can consider paging loading, and only a part of the data is loaded at a time.
• Caching: Caches loaded data to avoid duplicate requests. Can be cached using Vuex or browser.
• Code Optimization: Optimize your code, reduce unnecessary calculations and operations, and improve performance.

In short, building an efficient remote search cascade selection box requires you to have an in-depth understanding of Vue, Element-UI, asynchronous programming, and performance optimization. I hope this article can help you better master this skill and avoid falling into common pitfalls. Remember, the code is simple and easy to understand and efficient performance is the best way to go!

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