javascript - typescript - 不可分配给打字学生

Question

我的构造函数中有一个错误>> this.allStudents

class Students {
    public StudentsId: number;
    public StudentsName: string;
    public allStudents?: Students[];
    constructor() {
        this.allStudents = [
            { StudentsId: 100, StudentsName: 'Mahmoud'},
            { StudentsId: 101, StudentsName: 'Sami' },
            { StudentsId: 102, StudentsName: 'Osama' },
            { StudentsId: 103, StudentsName: 'Amer' },
            { StudentsId: 104, StudentsName: 'Ahmad' },
            { StudentsId: 105, StudentsName: 'Fadi' }
        ];
    }

    get getAllStudents() {
        return null;
    }
    getStudentById(_studentsId) {
        return this.allStudents.filter(x => x.StudentsId === _studentsId);
    }
    set addStudent(_student) {

    }


}

我不知道为什么会发生这个错误。我需要一些帮助来解决这个问题。

我如何在students类中使用这个接口(interface)？请检查接口(interface)IStudents如下:

interface IStudents {
    name: string,
    age: number,
    active:boolean
};

Answer 1

我不明白为什么您需要 Students 的递归结构，因此使用您感兴趣的属性定义一个 Student 并引用它。它可以是类、接口(interface)或类型。

下面的示例将学生与学生列表分开，您可能需要更改名称以使其更加明确。

interface Student {
    StudentsId: number;
    StudentsName: string;
}

class Students {
    public StudentsId: number;
    public StudentsName: string;
    public allStudents: Student[] = [];

    constructor() {
        this.allStudents = [
            { StudentsId: 100, StudentsName: 'Mahmoud'},
            { StudentsId: 101, StudentsName: 'Sami' },
            { StudentsId: 102, StudentsName: 'Osama' },
            { StudentsId: 103, StudentsName: 'Amer' },
            { StudentsId: 104, StudentsName: 'Ahmad' },
            { StudentsId: 105, StudentsName: 'Fadi' }
        ];
    }

    get getAllStudents() {
        return null;
    }

    getStudentById(_studentsId) {
        return this.allStudents.filter(x => x.StudentsId === _studentsId);
    }

    set addStudent(_student) {

    }
}

学生的层次结构

如果你确实需要学生的层次结构，你可以这样实现:

class Students {
    public subStudents: Students[] = [];

    constructor(public StudentsId: number, public StudentsName: string) {
        this.subStudents = [
            new Students(100, 'Mahmoud'),
            new Students(101, 'Sami'),
            new Students(102, 'Osama'),
            new Students(103, 'Amer'),
            new Students(104, 'Ahmad'),
            new Students(105, 'Fadi'),
        ];
    }

    get getAllStudents() {
        return null;
    }
    getStudentById(_studentsId) {
        return this.subStudents.filter(x => x.StudentsId === _studentsId);
    }
    set addStudent(_student) {

    }
}

数组类型的可选性

我在两个代码示例中都表达了我的观点:空数组是不可取的。您可以将其设置为非可选并将其实例化为空数组，这样就无需在使用前对数组进行 null 检查。