如何使用vue定义组件之——子组件调用父组件数据

1.定义父子模板template

 <div class="container">
        <my-father></my-father>
        <my-father></my-father>
        <my-father>

        </my-father>

        <!-- 此处无法调用子组件，子组件必须依赖于父组件进行展示 -->
        <!-- <my-children></my-children> -->
    </div>


    <template id="father">
        <div>
            <h3>我是父组件</h3>
            <h3>访问子组件的数据:</h3>
            <h3>{{ msg }}</h3>
            <h3>{{ name }}</h3>
            <h3>{{ age }}</h3>
            <h3>{{ user }}</h3>

            <my-children></my-children>
            <hr>

        </div>
    </template>

    <template id="children">
        <div>
            <h6>我是子组件</h6>
            <h6>访问子组件的数据:</h6>
        </div>
    </template>

2.创建Vue实例，如何建立父子关系

<script>
    new Vue({
        el: '.container',
        components: {
            'my-father': {//父组件
                template: '#father',
                data() {
                    return {
                        msg: "",
                        name: "",
                        age: null,
                        user: {
                            id: null,
                            username: ""
                        }
                    }
                },
                components: {
                    'my-children': { //子组件，只能在 my-father中调该组件
                        template: '#children',
                        data() {
                            return {
                                msg: "welcome children!",
                                name: "I'm a child!",
                                age: 6,
                                user: {
                                    id: 1001,
                                    username: 'admin'
                                }
                            }
                        }
                    }
                }
            }
        }
    })
</script>

技术：事件监听+事件触发

父组件在调用子组件时，监听子组件触发的自定义事件，并在父组件中定义回调方法，用来接收数据

    <template id="father">
        <div>
            <h3>我是父组件</h3>
            <h3>访问子组件的数据:</h3>
            <h3>{{ msg }}</h3>
            <h3>{{ name }}</h3>
            <h3>{{ age }}</h3>
            <h3>{{ user }}</h3>

            <!-- 监听子组件触发的数据 -->
            <my-children @e-child="getMsg"></my-children>
            <hr>
        </div>
    </template>

在子组件中使用`vm.$emit(事件名,数据)`触发自定义事件，将当前获取的数据，传给父类

                components: {
                    'my-children': { //子组件，只能在 my-father中调该组件
                        template: '#children',
                        data() {
                            return {
                                msg: "welcome children!",
                                name: "I'm a child!",
                                age: 6,
                                user: {
                                    id: 1001,
                                    username: 'admin'
                                }
                            }
                        },
                        created() {
                            //触发事件，向父组件传递数据
                            this.$emit('e-child', this.msg,this.name,this.age,this.user)
                        }
                    }
                }

父类定义一个方法，获取数据：

new Vue({
        el: '.container',
        components: {
            'my-father': {//父组件
                template: '#father',
                data() {
                    return {
                        msg: "",
                        name: "",
                        age: null,
                        user: {
                            id: null,
                            username: ""
                        }
                    }
                },
                methods: {
                    getMsg(msg,name,age,user) {
                        this.msg = msg;
                        this.name = name;
                        this.age = age;
                        this.user = user;
                    }
                }
            }
        }
    })

打印结果：