How to implement Vue and Element-UI cascade selector

Vue and Element-UI cascade selectors can directly use the el-cascader component in simple scenarios, but to write more elegant, efficient and robust code, you need to pay attention to the following details: Data source structure optimization: Flatten the data and use id and parentId to represent the parent-child relationship. Asynchronous loading data processing: handles loading status, error prompts and user experience. Performance optimization: Consider on-demand loading or virtual scrolling technology. Code readability and maintainability: Write comments, use meaningful variable names, and follow code specifications.

Vue and Element-UI cascade selectors: more than just a simple combination

You may wonder, Vue and Element-UI have ready-made components, can you just use them directly? That's right, in a simple scenario, just use el-cascader of Element-UI, but this article is not written for students who only want to pile components. We're going to talk about the details you might not have noticed, the techniques that will allow you to write more elegant, more efficient, and more robust code.

Let’s start with the basics. el-cascader itself is a powerful component, which helps you handle most of the tedious DOM operations and data binding. You just need to provide a data source and it will render a nice cascading selector. But the structure of the data source and how to handle user choices are the key.

Imagine a simple three-level linkage between province, city and district. The most direct way is to use a three-layer nested array:

 <code class="javascript">const options = [ { value: '北京', label: '北京', children: [ { value: '朝阳', label: '朝阳' }, { value: '海淀', label: '海淀' } ] }, { value: '上海', label: '上海', children: [ { value: '浦东', label: '浦东' }, { value: '黄浦', label: '黄浦' } ] } ];</code>

This looks good, but when the data is large, this thing becomes difficult to maintain. Just imagine, if the data is obtained asynchronously from the backend, you need to deal with various load states, error handling, and data format conversion. This cannot be solved by simple v-for .

A more elegant approach is to flatten the data and use a unique id and parentId to represent the parent-child relationship:

 <code class="javascript">const options = [ { id: 1, parentId: 0, label: '北京' }, { id: 2, parentId: 1, label: '朝阳' }, { id: 3, parentId: 1, label: '海淀' }, { id: 4, parentId: 0, label: '上海' }, { id: 5, parentId: 4, label: '浦东' }, { id: 6, parentId: 4, label: '黄浦' } ];</code>

In this way, no matter how large the data is, the structure remains consistent. You only need to configure props in el-cascader to specify value , label and children attributes. Element-UI will help you automatically build a tree structure.

But things are not over yet. When loading data asynchronously, you have to deal with loading status and error handling. Don’t forget the user experience: if the loading speed is slow, the user will be impatient; if there is an error, give user-friendly prompts. All of these require you to think carefully.

Go deeper and consider performance optimization. If the data volume is very large, rendering all data directly will affect performance. At this point, you can consider loading on demand, or using virtual scrolling technology. This requires a deep understanding of Vue's rendering mechanism.

Finally, don't forget the readability and maintainability of the code. Writing comments, using meaningful variable names, and following code specifications, these seemingly trivial things can greatly improve team collaboration efficiency and reduce bugs.

This article is not a simple component usage tutorial, but hopes to give you a deeper understanding of the implementation of Vue and Element-UI cascade selectors and write higher quality code. Remember that components are just tools, what really matters is how you use it and how you understand the principles behind it. Don’t forget that the world of code is full of pitfalls, but as long as you are careful, you can avoid them and write your own wonderful code.

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