Vue and Element-UI implement dynamic cascading drop-down boxes

When using the el-cascader component of Element-UI to implement dynamic cascading drop-down boxes, you need to pay attention to the following key steps: Ensure that the data structure meets the tree structure required by el-cascader. In the handleChange method, the next level option data is loaded asynchronously according to the selected superior option and updated the options attribute. Use nextTick or $forceUpdate to force update the view to reflect data updates. Consider using recursion or other advanced data processing methods to handle infinite cascades. Pay attention to performance optimization and best practices such as data caching, lazy loading, and code readability.

Vue and Element-UI implement dynamic cascading drop-down boxes: those pitfalls you may not know

Many people asked me how to complete the dynamic cascaded drop-down box of Vue and Element-UI. It looks simple and actually operates. Well, you know. We broke this article and talked about it carefully. Not only did we tell you how to do it, but more importantly, we told you the places where it is prone to fall into pitfalls and the mines I have stepped on.

Let’s talk about the conclusion first: Using the el-cascader component of Element-UI seems simple, but it’s not that easy to play with dynamic data. It has strict requirements on data structures. If you are not careful, you will easily have problems such as data loading and incomplete display of options.

You have to know some basic knowledge

You have to know what Vue is, what Element-UI is, and the concept of component development. Won't? Go and make up for your lessons! This thing cannot be explained clearly in just a few words. In addition, you should also have a general understanding of asynchronous operations, promises, and data requests.

The temper of el-cascader component

The core of el-cascader component lies in its options attribute. This property determines what your drop-down box displays. But it is not just a random array, it requires a specific tree structure data. This structure must be standardized, otherwise it will strike. Don't believe it? You try it!

Code example: Test the slightest

Suppose you already have a backend interface and can return such JSON data:

 <code class="json">[ { value: '1', label: '省份A', children: [ { value: '1-1', label: '城市A1' }, { value: '1-2', label: '城市A2' } ] }, { value: '2', label: '省份B', children: [ { value: '2-1', label: '城市B1' } ] } ]</code>

Then, your Vue code looks like this:

 <code class="vue"><template> <el-cascader v-model="selectedOptions" :options="options"></el-cascader> </template> <script> export default { data() { return { selectedOptions: [], options: [] }; }, mounted() { this.fetchOptions(); }, methods: { async fetchOptions() { const response = await this.$http.get(&#39;/api/options&#39;); // 假设你的接口地址是/api/options this.options = response.data; }, handleChange(value) { console.log(value); // 处理你的选择结果// 这里可以根据选择的省份，异步获取对应的城市数据，然后更新options 属性} } }; </script></code>

The essence of dynamic loading

The above code is just the most basic. The real dynamic cascade lies in handleChange method. After selecting a superior option, you need to re-request the backend interface according to this selection, obtain the data of the next level of options, and then update options attribute. This part requires you to have a good understanding of asynchronous operations, and you must handle the timing of data updates to avoid data confusion.

Points and solutions

• The data structure is not standardized: this is definitely the biggest pitfall. Double-check your data structure to make sure it complies with el-cascader requirements. A misalignment can drive you crazy for a long time.
• Asynchronous loading causes data not to be updated: After the asynchronous operation is completed, the options attribute may not be updated yet, resulting in an error in the interface. You need to use nextTick or $forceUpdate to force update the view.
• Complexity of infinite cascades: If you have many cascade levels, the complexity of your code will increase dramatically. You need to consider using recursion or other more advanced data processing methods.

Performance optimization and best practices

• Data cache: If the amount of data is large, you can consider cacheing the already loaded data to avoid duplicate requests.
• Lazy loading: only load the currently required hierarchical data to improve performance.
• Code readability: Write clear and easy-to-understand code for easy maintenance.

In short, Vue and Element-UI implement dynamic cascading drop-down boxes, which seems simple, but in fact it is not. You need to have a deep understanding of Vue, Element-UI, asynchronous operations and data structures. Remember, practice more, debug more, and hit more pitfalls to truly master it. I hope this sharing can help you avoid detours.

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