成功使用vue props

父组件：
<template>
  <div class="app-container">
    <el-form ref="form" :model="form" :rules="rules2" label-width="120px">
      <el-form-item label="用户名" prop="username">
        <el-rate v-model="form.username" show-text></el-rate>
      </el-form-item>
      <el-form-item label="添加时间" prop="addtime">
        <el-date-picker
          v-model="form.addtime"
          type="datetime"
          value-format="yyyy-MM-dd HH:mm:ss"
          placeholder="选择日期时间"
        ></el-date-picker>
      </el-form-item>
      <el-form-item label="数量" prop="num1">
        <el-input
          type="text"
          oninput="value=value.replace(/[^\d]/g,'')"
          maxlength="9"
          v-model="form.num1"
          placeholder="请输入数量"
          clearable
        ></el-input>
      </el-form-item>
      <el-form-item>
        <test_props username="sdafsdaaaaaaaaaaaaaaa是" />
      </el-form-item>
      <el-form-item style="text-align:center">
        <el-button type="primary" @click="add();">确定添加</el-button>
      </el-form-item>
    </el-form>
  </div>
</template>
<script>
import { add } from "@/api/test";
import test_props from "@/views/form/test_props.vue";
export default {
  components: {
    test_props,
  },
  data() {
    return {
      form: {
        addtime: new Date().toUTCString(),
        num1: 0,
      },
      rules2: {},
    };
  },

  methods: {},
};
</script>

<style scoped>
.line {
  text-align: center;
}
</style>

子组件：
test_props.vue
<template>
  <div class="app-container">
    <el-form ref="form" :model="form" :rules="rules2" label-width="120px">
      <el-form-item label="用户名" >
         <el-input v-model="username" />
      </el-form-item>
      <el-form-item style="text-align:center">
        <el-button type="primary" @click="add();">确定添加</el-button>
      </el-form-item>
    </el-form>
  </div>
</template>
<script>
import { add } from "@/api/test";
export default {
  data() {
    return {
      form: {},
      rules2: {},
    };
  },
  props:{
    username:String,
  },
  methods: {
    add() {
      //先判断表单是否通过了判断
      this.$refs.form.validate((valid) => {
        //代表通过验证 ,将参数传回后台
        if (valid) {
          this.form.username2 = "safdsa33333";
          let params = Object.assign({}, this.form);
          add(params).then((res) => {
            this.$message({
              type: "info",
              message: res.Message,
            });
            if (res.Code == 702) {
              return;
            }
            this.$router.push("/test_list");
          });
        }
      });
    },
  },
};
</script>

<style scoped>
.line {
  text-align: center;
}
</style>