Vue and Element-UI cascaded drop-down box data verification

Common problems with data verification of Vue and Element-UI cascaded drop-down boxes include: tree-like data structures, parent-child relationships, and asynchronous verification. The solution is: write verification logic in the parent component, listen to change events and write custom rules; pay attention to asynchronous verification, manually call the validateField or validate method to update the verification state; optimize performance to avoid complex calculations; handle exceptions, such as network request failure; follow the readability principle and write concise and easy-to-understand code.

Vue and Element-UI cascaded drop-down box data verification: those pitfalls you may not know

Many students will encounter data verification problems in cascading selection boxes when using Vue and Element-UI to do projects. This thing looks simple, it's really useful, and it's a lot of tricks. In this article, let’s talk about how to solve this problem gracefully and avoid common minefields. After reading it, you can write efficient and robust code without scratching your head for verification problems.

Let’s talk about the basics first. Vue's own verification mechanism is very flexible, and can achieve many powerful functions with Element-UI components. el-cascader component of Element-UI itself does not have built-in verification function, so we need to do it ourselves. This cannot be done by simple v-model binding and some simple if judgments. Think about it, the data structure of the cascade selection box is tree-like, and checking needs to consider whether the selected node complies with the rules and the relationship between the parent node and the child node. This complexity suddenly increases.

Let's explore the core issue in depth: how to verify. The most intuitive solution is to write verification logic directly in the parent component of el-cascader . For example, you can listen to change events and write verification rules in event callback functions.

 <code class="vue"><template> <el-form :model="formData" :rules="rules" ref="formRef"> <el-form-item label="级联选择框" prop="cascaderValue"> <el-cascader v-model="formData.cascaderValue" :options="options"></el-cascader> </el-form-item> <el-button type="primary">提交</el-button> </el-form> </template> <script> import { ref, reactive } from &#39;vue&#39;; export default { setup() { const formData = reactive({ cascaderValue: [] }); const options = [ // 你的级联选择框数据]; const rules = { cascaderValue: [{ required: true, message: &#39;请选择&#39;, trigger: &#39;change&#39; }] }; const formRef = ref(null); const handleCascaderChange = (value) => { // 在这里进行自定义校验if (value && value.length > 0 && value[0].value === &#39;invalid&#39;) { formRef.value.validateField(&#39;cascaderValue&#39;); } }; const handleSubmit = () => { formRef.value.validate((valid) => { if (valid) { console.log(&#39;提交成功&#39;, formData.cascaderValue); } else { console.log(&#39;校验失败&#39;); } }); }; return { formData, options, rules, formRef, handleCascaderChange, handleSubmit }; } }; </script></code>

In this code, we use el-form and el-form-item components of Element-UI for form verification. rules object defines the verification rules. The handleCascaderChange function is triggered when the value of the cascade selection box changes to perform custom verification. The handleSubmit function submits the form. Note that this is just a simple example. In actual application, you need to write more complex verification logic according to your needs.

Here is a point that is easy to ignore: asynchronous verification. If your verification logic requires asynchronous operations, such as requesting a backend interface, then you need to use async/await or Promise to handle the asynchronous verification results. Remember, asynchronous verification must manually call validateField or validate method after the verification is completed to update the verification status of the form.

In terms of performance optimization, avoid overly complex calculations in handleCascaderChange . If you have a large amount of data, consider using virtual lists or other optimization strategies to improve performance. Remember that the readability and maintainability of the code are also important, and try to write concise and easy-to-understand code.

Finally, don't forget to deal with various exceptions, such as network request failures, data format errors, etc. A perfect error handling mechanism allows you to be at ease when facing various unexpected situations. In short, the data verification of the cascading selection box seems simple, but in fact, it requires careful consideration of various details to write high-quality code. Practice more and think more, and you will definitely become a verification expert in Vue and Element-UI!

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