写给新手的 el-form validate 使用 && 实现原理源码级分析

关于 el-form validate的使用以及源码分析

v-model， rules 和 ref

• v-model 配合 prop 使用，对应的是要校验字段的值（prop 一定是在 el-form-itme上面，在源码部分会解释为什么）
• rule 和 prop 对应，指的是每个字段的校验规则（在源码部分会解释为什么）
• ref 最后一步校验使用，和v-model 对应

<el-form :model="ruleForm" :rules="rules" ref="ruleForm" label-width="100px">
  <el-form-item label="活动名称" prop="name">
    <el-input v-model="ruleForm.name"></el-input>
  </el-form-item>
 <el-form-item label="年龄" prop="age">
    <el-input v-model.number="ruleForm.age"></el-input>
  </el-form-item>
  <el-form-item>
    <el-button type="primary" @click="submitForm('ruleForm')">立即创建</el-button>
    <el-button @click="resetForm('ruleForm')">重置</el-button>
  </el-form-item>
</el-form>
<script>
  var checkAge = (rule, value, callback) => {
  
  
  	// rule => { validator: '',  field: "score.0", fullField: "score.0", type: "string", max_age: '' ...}
    // field 是 对应props里面的值
    // validator 是async-validator 里面的 validator(description)
    // value 要校验的值
    //console.log(rule.max_age)
    
    
    
    if (!value) {
       return callback(new Error('年龄不能为空'));
     }
     if (!Number.isInteger(value)) {
         callback(new Error('请输入数字值'));
      } else {
        if (value < rule.max_age) {
          callback(new Error('必须年满18岁'));
        } else {
          callback();
        }
      }
  };
  export default {
    data() {
      return {
        ruleForm: {
          name: '',
          age:''
        },
        rules: {
          name: [
            { required: true, message: '请输入活动名称', trigger: 'blur', validator: function() {} },
            { min: 3, max: 5, message: '长度在 3 到 5 个字符', trigger: 'blur', validator: function() {} }
          ],
          age: [
            {max_age：18， validator: checkAge, trigger: 'blur' }// checkAge自定义规则函数
          ]
        }
      };
    },
    methods: {
      submitForm(formName) {
        this.$refs[formName].validate((valid, form) => {
        
        // form 里面是校验没通过的prop
        
          if (valid) {
            alert('submit!');
          } else {
            console.log('error submit!!')
          }
        });
      },
      resetForm(formName) {
        this.$refs[formName].resetFields();
      }
    }
  }
</script>

• 也可以将校验规则写在form上面

<el-form :model="numberValidateForm" ref="numberValidateForm" label-width="100px" class="demo-ruleForm">
  <el-form-item
    label="年龄"
    prop="age"
    :rules="[
      { required: true, message: '年龄不能为空'},
      { type: 'number', message: '年龄必须为数字值'}
    ]">
    <el-input type="age" v-model.number="numberValidateForm.age" autocomplete="off"></el-input>
  </el-form-item>

• 以至于循环使用也是没有问题的

<el-form>
  <el-form-item
    v-for="(domain, index) in dynamicValidateForm.domains"
    :label="'域名' + index"
    :key="domain.key"
    :prop="`domains.${index}.value`" //绑定的prop
    :rules="[
     { required: true, message: '域名不能为空', trigger: 'blur' },
     {reg：/^--------$/， validator: checkDomain, trigger: 'blur' }
    ]"
  >
</el-form-item>

然后来分析一波源码

// form.vue
//#76 form-item会emit一个事件，接收就好
created() {
    this.$on('el.form.addField', (field) => {
      if (field) {
        this.fields.push(field);
      }
    });
    /* istanbul ignore next */
    this.$on('el.form.removeField', (field) => {
      if (field.prop) {
        this.fields.splice(this.fields.indexOf(field), 1);
      }
    });
  },

// # 109 
// 我们使用的this.$refs['formname'].validate 里面的validate 就是这个validate
validate(callback) {
    if (!this.model) { // 如果没有模板直接报错
      console.warn('[Element Warn][Form]model is required for validate to work!');
      return;
    }
    let promise;
    // if no callback, return promise
    if (typeof callback !== 'function' && window.Promise) {
      promise = new window.Promise((resolve, reject) => {
        callback = function(valid) { // 这个valid是从form-item 里面返回的，下面会讲
          valid ? resolve(valid) : reject(valid);
        };
      });
    }
    let valid = true;
    let count = 0;
    // 如果需要验证的fields为空，调用验证时立刻返回callback
    if (this.fields.length === 0 && callback) {
      callback(true);
    }
    let invalidFields = {};
    this.fields.forEach(field => { // 猜测这个field应该是一个form-item 的示例
      field.validate('', (message, field) => { // 这个validate也是form-item里面的
        if (message) {
          valid = false; // 存在校验没通过
        }
        invalidFields = objectAssign({}, invalidFields, field); // 应该是重新了Object.assign
        if (typeof callback === 'function' && ++count === this.fields.length) { // 最后一个的处理
          callback(valid, invalidFields); // 如果cb是函数，正常执行，参数是校验结果和校验失败的field
        }
      });
    });
    if (promise) {
      return promise;// 如果没有cb，那么返回一个promise，如果有promise返回一个promise， 这样写提高兼容性
    }
  },

// form-item.vue ,这里主要讲几个关键的方法
// # 54
  provide() {
    return {
      elFormItem: this
    };
  }, 
  inject: ['elForm'],
// 对内注入elForm, 对外抛出elFormItem

//#189 每个form-item 单独校验
import AsyncValidator from 'async-validator';
  validate(trigger, callback = noop) { // 这个就是我上文提到的form-item 里面的validate
      this.validateDisabled = false;
      const rules = this.getFilteredRule(trigger); //获取rules
      if ((!rules || rules.length === 0) && this.required === undefined) { // 没有rules, 直接通过
        callback();
        return true; 
      }
      this.validateState = 'validating';
      const descriptor = {};
      if (rules && rules.length > 0) {
        rules.forEach(rule => {
          delete rule.trigger;
        });
      }
      descriptor[this.prop] = rules; //每个form-item 单独校验
      const validator = new AsyncValidator(descriptor);
      const model = {};
      model[this.prop] = this.fieldValue; // 这里就是为什么一定要有model， 而且props必须可以直接访问
      validator.validate(model, { firstFields: true }, (errors, invalidFields) => { // 参考asyn-validator 不展开
      // validation failed, errors is an array of all errors
      // fields is an object keyed by field name with an array of
      // errors per field
      // https://github.com/yiminghe/async-validator
      //- firstFields: Boolean|String[], Invoke callback when the first validation rule of the specified sofield generates an error, no more validation rules of the same field are processed. true means all fields. 所以项，只要有规则一个产生error， 该项后面规则都不执行。
      //说到底就是对async-validator一个封装
        this.validateState = !errors ? 'success' : 'error';
        this.validateMessage = errors ? errors[0].message : '';
        callback(this.validateMessage, invalidFields);
        this.elForm && this.elForm.$emit('validate', this.prop, !errors, this.validateMessage || null);
      });
    },


//# 252
 getRules() {
    let formRules = this.form.rules; // parent 组件的rules
    const selfRules = this.rules; // prop 传入的rules
    const requiredRule = this.required !== undefined ? { required: !!this.required } : []; // prop 传入
    const prop = getPropByPath(formRules, this.prop || ''); // 判断parent 传的rules是否和prop传入冲突
    formRules = formRules ? (prop.o[this.prop || ''] || prop.v) : []; // 以prop 为准
    return [].concat(selfRules || formRules || []).concat(requiredRule); // 整合
  },
  getFilteredRule(trigger) {
    const rules = this.getRules();
    return rules.filter(rule => {
      if (!rule.trigger || trigger === '') return true; // 全触发
      if (Array.isArray(rule.trigger)) {
        return rule.trigger.indexOf(trigger) > -1; //按需触发
      } else {
        return rule.trigger === trigger;
      }
    }).map(rule => objectAssign({}, rule));
  },

// #130
  form() { // 找到parent为el-form的组件
    let parent = this.$parent;
    let parentName = parent.$options.componentName;
    while (parentName !== 'ElForm') {
      if (parentName === 'ElFormItem') {
        this.isNested = true;
      }
      parent = parent.$parent;
      parentName = parent.$options.componentName;
    }
    return parent;
  },

// util #47
export function getPropByPath(obj, path, strict) {
  let tempObj = obj;
  path = path.replace(/\[(\w+)\]/g, '.$1'); // enleve []
  path = path.replace(/^\./, ''); // enleve first.

  let keyArr = path.split('.');
  let i = 0;
  for (let len = keyArr.length; i < len - 1; ++i) {
    if (!tempObj && !strict) break;
    let key = keyArr[i];
    if (key in tempObj) {
      tempObj = tempObj[key]; // neste address
    } else {
      if (strict) {
        throw new Error('please transfer a valid prop path to form item!');
      }
      break;
    }
  }
  return {
    o: tempObj,
    k: keyArr[i],
    v: tempObj ? tempObj[keyArr[i]] : null
  };
};