在TypeScript中凝胶化类的所有模型属性

时间:2016-05-28 04:25:23

标签: javascript reflection typescript

我有以下TypeScript类:

export class City {
  name: string;
  fullName: string;
  country: string;
  countryCode: string;
  center: GeoPoint;
}

我需要一种在运行时获取所有模型属性的方法。例如:

static init(obj): City {

    let city = new City();

    for (var i in obj) {
      if (i == "exists in City model") {
        city[i] = obj[i];
      }
    }
}

在TypeScript中有一种简单的方法吗?我不希望需要维护所有模型属性名称的数组来检查它。

2 个答案:

答案 0 :(得分:1)

如果在TypeScript Playground上检查TypeScript编译器生成的输出,则它不会设置任何没有默认值的类属性。因此,可能的方法是使用null初始化所有这些:

export class City {
    name: string = null;
    fullName: string = null;
    country: string = null;
    countryCode: string = null;
    center: string = null;

    ...
}

然后使用typeof检查对象上是否存在对象属性。您更新的代码:

export class City {
  name: string = null;
  fullName: string = null;
  country: string = null;
  countryCode: string = null;
  center: string = null;

  static init(obj): City {

    let city = new City();

    for (var i in obj) {
      if (typeof(obj[i]) !== 'undefined') {
        city[i] = obj[i];
      }
    }
    return city
  }
}

var c = City.init({
  name: 'aaa',
  country: 'bbb',
});

console.log(c);

使用node编译和运行时打印输出:

City {
  name: 'aaa',
  fullName: null,
  country: 'bbb',
  countryCode: null,
  center: null
}

答案 1 :(得分:0)

您可以尝试使用TypeScript编译器的增强版本,该版本允许您在运行时检索类/接口元数据(字段,方法,泛型类型等)。例如,您可以写:

export class City {
    name: string = null;
    fullName: string = null;
    country: string = null;
    countryCode: string = null;
    center: string = null;
}

function printMembers(clazz: Class) {
    let fields = clazz.members.filter(m => m.type.kind !== 'function'); //exclude methods.
    for(let field of fields) {
        let typeName = field.type.kind;
        if(typeName === 'class' || typeName === 'interface') {
            typeName = (<Class | Interface>field.type).name;
        }
        console.log(`Field ${field.name} of ${clazz.name} has type: ${typeName}`);
    }
}

printMembers(City.getClass());

这是输出:

$ node main.js
Field name of City has type: string
Field fullName of City has type: string
Field country of City has type: string
Field countryCode of City has type: string
Field center of City has type: string

然后,您可以在City循环中使用for元数据来检查特定实例上是否存在值。

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