父更新vuejs时子组件不更新

Question

我有一个将对象传递给子组件的 vue 实例。子组件有一个复选框，单击该复选框时会调用 vue 实例处理的事件，以更新传递给子组件的父对象。基于vue documentation，我认为这会导致子组件更新相关字段。但是，当我单击复选框时，日期字段并没有像我预期的那样更新。在下图中，当我选中管理名称复选框时，我希望会出现当前日期，但我没有看到任何日期。我在这里错过了什么？

设计

父实例

new Vue({
    el: "#evaluations-app",
    data: {
        evaluation: new Evaluation()        
    },
    methods: {        
        updateEmployeeSO: function (newSO, newSODate) {
            this.evaluation.EmployeeSO = newSO;
            this.evaluation.EmployeeSODate = newSODate;
        },
        updateReviewerSO: function (newSO, newSODate) {
            this.evaluation.ReviewerSO = newSO;
            this.evaluation.ReviewerSODate = newSODate;
        },
        updateManagementSO: function (newSO, newSODate) {
            this.evaluation.ManagementSO = newSO;
            this.evaluation.ManagementSODate = newSODate;
        }
});

子组件

Vue.component('sign-off', {
    props: ['initEvaluation', 'perspective'],
    template: `
        <div class="sign-off-comp">
            <div class="sign-off-item">
                <div class="sign-off-field-1 col-1">{{evaluation.EmployeeName}}</div>
                <input :disabled="!enableEmployeeSO" v-model="evaluation.EmployeeSO" class="sign-off-field-2 col-2" type="checkbox" @click="EmployeeSOChanged"/>
                <div class="sign-off-field-3 col-3">{{employeeSODate}}</div>                
            </div>  
            <div class="sign-off-item">
                <div class="sign-off-field-1 col-1">{{evaluation.ReviewerName}}</div>
                <input :disabled="!enableReviewerSO" v-model="evaluation.ReviewerSO" class="sign-off-field-2 col-2" type="checkbox" @click="ReviewerSOChanged"/>
                <div class="sign-off-field-3 col-3">{{reviewerSODate}}</div>                
            </div>   
            <div class="sign-off-item">
                <div class="sign-off-field-1 col-1">{{evaluation.ManagementName}}</div>
                <input :disabled="!enableManagementSO" v-model="evaluation.ManagementSO" class="sign-off-field-2 col-2" type="checkbox" @click="ManagementSOChanged"/>
                <div class="sign-off-field-3 col-3">{{managementSODate}}</div>                
            </div>                   
        </div>
    `,
    data: function () {
        return {
            evaluation: this.initEvaluation,
            employeeClicked: false,
            reviewerClicked: false,
            managementClicked: false,
            currentCommentSource: this.perspective
        }
    },
    methods: {
        EmployeeSOChanged: function () {
            this.employeeClicked = true;
            //this.evaluation.EmployeeSODate == null || this.evaluation.EmployeeSODate == "" ? this.evaluation.EmployeeSODate = Helpers.getCurrentDate() : this.evaluation.EmployeeSODate = "";
            this.$emit('employee-so-changed', this.evaluation.EmployeeSO, this.evaluation.EmployeeSODate);
        },
        ReviewerSOChanged: function () {
            this.reviewerClicked = true;
            //this.evaluation.ReviewerSODate == null || this.evaluation.ReviewerSODate == "" ? this.evaluation.ReviewerSODate = Helpers.getCurrentDate() : this.evaluation.ReviewerSODate = "";
            this.$emit('reviewer-so-changed', this.evaluation.ReviewerSO, this.evaluation.ReviewerSODate);
        },
        ManagementSOChanged: function () {
            this.managementClicked = true;
            //this.evaluation.ManagementSODate == null || this.evaluation.ManagementSODate == "" ? this.evaluation.ManagementSODate = Helpers.getCurrentDate() : this.evaluation.ManagementSODate = "";
            this.$emit('management-so-changed', this.evaluation.ManagementSO, this.evaluation.ManagementSODate == null || this.evaluation.ManagementSODate == "" ? Helpers.getCurrentDate() : "");
        }
    },
    computed: {
        enableEmployeeSO: function () {
            return (this.perspective == "Employee" && !this.evaluation.EmployeeSO) || this.employeeClicked;
        },
        enableReviewerSO: function () {
            return (this.perspective == "Reviewer" && !this.evaluation.ReviewerSO && this.evaluation.EmployeeSO) || this.reviewerClicked;
        },
        enableManagementSO: function () {
            return (this.perspective == "Management" && !this.evaluation.ManagementSO && this.evaluation.ReviewerSO && this.evaluation.EmployeeSO) || this.managementClicked;
        },
        employeeSODate: function () {
            return this.evaluation.EmployeeSODate != null && this.evaluation.EmployeeSODate == new Date("01-01-1900") ? "" : this.evaluation.EmployeeSODate != null && this.evaluation.EmployeeSODate.length >= 10 ? this.evaluation.EmployeeSODate.substring(0, 10) : this.evaluation.EmployeeSODate;
        },
        reviewerSODate: function () {
            return this.evaluation.ReviewerSODate != null && this.evaluation.ReviewerSODate == new Date("01-01-1900") ? "" : this.evaluation.ReviewerSODate != null && this.evaluation.ReviewerSODate.length >= 10 ? this.evaluation.ReviewerSODate.substring(0, 10) : this.evaluation.ReviewerSODate;
        },
        managementSODate: function () {
            return this.evaluation.ManagementSODate != null && this.evaluation.ManagementSODate == new Date("01-01-1900") ? "" : this.evaluation.ManagementSODate != null && this.evaluation.ManagementSODate.length >= 10 ? this.evaluation.ManagementSODate.substring(0, 10) : this.evaluation.ManagementSODate;
        }
    }
});

型号

export class Evaluation {
    private _EmployeeName: string;
    private _EmployeeSO: boolean;
    private _EmployeeSODate: Date;
    private _ReviewerName: string;
    private _ReviewerSO: boolean;
    private _ReviewerSODate: Date;
    private _ManagementReviewerName: string;
    private _ManagementReviewerSO: boolean;
    private _ManagementReviewerSODate: Date;

    constructor() {
        this._EmployeeName = "";
        this._EmployeeSO = false;
        this._EmployeeSODate = new Date("01-01-1900");
        this._ReviewerName = "";
        this._ReviewerSO = false;
        this._ReviewerSODate = new Date("01-01-1900");
        this._ManagementReviewerName = "";
        this._ManagementReviewerSO = false;
        this._ManagementReviewerSODate = new Date("01-01-1900");
    }

    get EmployeeName(): string {
        return this._EmployeeName;
    }
    set EmployeeName(employeeName: string) {
        if (this._EmployeeName != employeeName) {
            this._EmployeeName = employeeName;
        }
    }

    get EmployeeSO(): boolean {
        return this._EmployeeSO;
    }
    set EmployeeSO(employeeSO: boolean) {
        if (this._EmployeeSO != employeeSO) {
            this._EmployeeSO = employeeSO;
        }
    }

    get EmployeeSODate(): Date {
        return this._EmployeeSODate;
    }
    set EmployeeSODate(employeeSODate: Date) {
        if (this._EmployeeSODate != employeeSODate) {
            this._EmployeeSODate = employeeSODate;
        }
    }

    get ReviewerName(): string {
        return this._ReviewerName;
    }
    set ReviewerName(reviewerName: string) {
        if (this._ReviewerName != reviewerName) {
            this._ReviewerName = reviewerName;
        }
    }

    get ReviewerSO(): boolean {
        return this._ReviewerSO;
    }
    set ReviewerSO(reviewerSO: boolean) {
        if (this._ReviewerSO != reviewerSO) {
            this._ReviewerSO = reviewerSO;
        }
    }

    get ReviewerSODate(): Date {
        return this._ReviewerSODate;
    }
    set ReviewerSODate(reviewerSODate: Date) {
        if (this._ReviewerSODate != reviewerSODate) {
            this._ReviewerSODate = reviewerSODate;
        }
    }

    get ManagementReviewerName(): string {
        return this._ManagementReviewerName;
    }
    set ManagementReviewerName(managementReviewerName: string) {
        if (this._ManagementReviewerName != managementReviewerName) {
            this._ManagementReviewerName = managementReviewerName;
        }
    }

    get ManagementReviewerSO(): boolean {
        return this._ManagementReviewerSO;
    }
    set ManagementReviewerSO(managementReviewerSO: boolean) {
        if (this._ManagementReviewerSO != managementReviewerSO) {
            this._ManagementReviewerSO = managementReviewerSO;
        }
    }

    get ManagementReviewerSODate(): Date {
        return this._ManagementReviewerSODate;
    }
    set ManagementReviewerSODate(managementReviewerSODate: Date) {
        if (this._ManagementReviewerSODate != managementReviewerSODate) {
            this._ManagementReviewerSODate = managementReviewerSODate;
        }
    }
}

更新

我刚刚注意到，在我的子组件中，我使用了MangementSO 和ManagementSODate，而模型使用了ManagementReviewerSO 和ManagementReviewerSODate。更改这些修复了我的代码。但是，基于下面的讨论，我有点困惑，为什么将 props 放入本地数据是处理这种情况的不正确方法。有人可以解释一下吗？

Answer 1

用props初始化数据属性没有错。我认为这里的许多 cmets 中最大的混淆来源是initEvaluation 是一个对象。在这种情况下，对该对象的任何更改都将反映在使用该对象的任何地方。

在有问题的代码中，父组件中的evaluation 和子组件中的evaluation是同一个对象。对该对象所做的更改将反映在父对象中，并且 Vue 不会 no 抱怨，因为您在技术上并没有改变对对象的引用，您只是在更改它的属性的值。

通常，如果您将 primitive 值作为属性传递，Vue 会发出警告。假设您传递了一个字符串值，然后将该值与v-model 一起使用。在那种的情况下，Vue 会抛出一个警告（在开发版本中）你正在改变一个属性。警告有两个原因；首先是因为该值没有传播到父级（这可能是意外行为），其次是因为每当 父级 中的数据发生更改时，它都会覆盖孩子。

但是，当对象或数组作为属性传递时，Vue 只会在您更改对象引用时报错。例如，在您的代码中，如果您要这样做：

this.initEvaluation = new Evaluation()

Vue 会抱怨你正在改变一个属性。但是，在您的代码中，您只是更改了initEvaluation 的 properties，这不会导致警告，并且还会导致这些值在 任何地方 反映出来，因为您是随处更新相同的对象。

其中一个后果是，在您的代码中有效地设置 evaluation: this.initEvaluation 是虚假的。您可以在模板中使用initEvaluation 并获得与使用evaluation 相同的结果。同样，这是因为它们是 same 对象。这是路易斯试图解释的部分内容。在这种情况下，路易斯的第一句话有点误导。数据函数只调用once，这意味着用属性初始化的数据只会接收一次属性的值。但是，因为 initEvaluation 是一个对象，所以在问题的代码中并不重要。对象 reference 永远不会改变，只有属性会改变。如果父级出于某种原因更改引用，则子级中的evaluation 将不会使用新的引用进行更新。 p>

对于一个对象是否希望立即反映更新是否值得商榷。在许多情况下，您希望控制何时 更新发生。在这些情况下，您可能会执行类似evaluation: Object.assign({}, this.initEvaluation) 的操作，它会生成initEvaluation 对象的副本。这样做的好处是您可以对子组件中的对象进行任意数量的更改，而这些更改不会反映在组件外部。然后，在您验证所有更改都正确后，您可以发出这些更改。

Answer 2

当您基于 props（initEvaluation 和 perspective）创建 data 属性时，它们不再依赖于道具，并且您仅引用数据，就好像它们只是副本一样，但不是收到的实际道具。所以，他们不会对道具做出反应。

由于您似乎没有在组件中更新它们，您可以直接引用props，而不是从props 创建的data。

编辑：从头开始，你在evaluation 上使用v-model，所以如果你直接引用它们，你会更改道具。

所以，一般来说，我会从数据中删除它：

evaluation: this.initEvaluation
// ...
currentCommentSource: this.perspective

并直接引用props，并按照文档中的建议将v-model 替换为:value 和@input。