我有一个这样定义的枚举:

export enum GoalProgressMeasurements {
    Percentage = 1,
    Numeric_Target = 2,
    Completed_Tasks = 3,
    Average_Milestone_Progress = 4,
    Not_Measured = 5
}

然而,我希望它被表示为一个对象数组/列表从我们的API如下:

[{id: 1, name: 'Percentage'}, 
 {id: 2, name: 'Numeric Target'},
 {id: 3, name: 'Completed Tasks'},
 {id: 4, name: 'Average Milestone Progress'},
 {id: 5, name: 'Not Measured'}]

是否有简单和本地的方法来做到这一点,或者我必须构建一个函数,将枚举转换为int和字符串,并将对象构建为数组?


当前回答

一个棘手的地方是TypeScript会在触发对象中'double'映射enum,所以它可以通过键和值访问。

enum MyEnum {
    Part1 = 0,
    Part2 = 1
}

将以

{
   Part1: 0,
   Part2: 1,
   0: 'Part1',
   1: 'Part2'
}

所以你应该在映射之前先过滤对象。所以@Diullei的解决方案是正确的。这是我的实现:

// Helper
const StringIsNumber = value => isNaN(Number(value)) === false;

// Turn enum into array
function ToArray(enumme) {
    return Object.keys(enumme)
        .filter(StringIsNumber)
        .map(key => enumme[key]);
}

像这样使用它:

export enum GoalProgressMeasurements {
    Percentage,
    Numeric_Target,
    Completed_Tasks,
    Average_Milestone_Progress,
    Not_Measured
}

console.log(ToArray(GoalProgressMeasurements));

其他回答

该方法基于语句: enum的键不能是数字

export const isNumeric = (num?: Value | null): num is number => {
  if (num === undefined || num === null) {
    return false;
  } 
  
  const number = +num;

  if (number - number !== 0) {
    // Discard Infinity and NaN
    return false;
  }

  if (number === num) {
    return true;
  }

  if (typeof num === 'string') {
    return !(number === 0 && num.trim() === '');
  }
  return false;
};

enum En  {
  ewq1 = 1,
  we2 = 'ss',
  sad = 'sad',
}

type TEnum = {
    [id: string]: number | string;
}

export const getEnumValues = <T extends TEnum>(enumerable: T) =>
  Object.keys(enumerable)
    .filter((x) => !isNumeric(x))
    .map((key) => enumerable[key] as T[keyof T]) 

console.log(getEnumValues(En)) // [1, "ss", "sad"] 

只有一句话:

Object.entries(GoalProgressMeasurements).map(([key, value]) => ({id: key, value: value}))

我不喜欢上面的答案,因为它们都不能正确地处理字符串/数字的混合,可以在TypeScript enum中作为值。

下面的函数遵循TypeScript枚举的语义,给出键到值的正确映射。从那里,获取一个对象数组或者仅仅是键或者仅仅是值是很简单的。

/**
 * Converts the given enum to a map of the keys to the values.
 * @param enumeration The enum to convert to a map.
 */
function enumToMap(enumeration: any): Map<string, string | number> {
  const map = new Map<string, string | number>();
  for (let key in enumeration) {
      //TypeScript does not allow enum keys to be numeric
      if (!isNaN(Number(key))) continue;

      const val = enumeration[key] as string | number;

      //TypeScript does not allow enum value to be null or undefined
      if (val !== undefined && val !== null)
          map.set(key, val);
  }

  return map;
}

使用示例:

enum Dog {
    Rover = 1,
    Lassie = "Collie",
    Fido = 3,
    Cody = "Mutt",
}

let map = enumToMap(Dog); //Map of keys to values

let objs = Array.from(map.entries()).map(m => ({id: m[1], name: m[0]})); //Objects as asked for in OP
let entries = Array.from(map.entries()); //Array of each entry
let keys = Array.from(map.keys()); //An array of keys
let values = Array.from(map.values()); //An array of values

我还要指出OP是逆向思考枚举的。枚举中的“键”在技术上是在左边,而值在右边。TypeScript允许你尽可能多地重复RHS上的值。

另一种方法是

export const GoalNames = {
    [GoalProgressMeasurements.Percentage] = 'Percentage',
    [GoalProgressMeasurements.Numeric_Target] = 'Numeric Target',
    [GoalProgressMeasurements.Completed_Tasks] = 'Completed Tasks',
    [GoalProgressMeasurements.Average_Milestone_Progress] = 'Average Milestone Progress',
    [GoalProgressMeasurements.Not_Measured] = 'Not Measured'
}

你可以调用:

const name = GoalNames[goalEnumVal];

枚举是运行时存在的真实对象。所以你可以这样反向映射:

let value = GoalProgressMeasurements.Not_Measured;
console.log(GoalProgressMeasurements[value]);
// => Not_Measured

基于此,您可以使用以下代码:

export enum GoalProgressMeasurements {
    Percentage = 1,
    Numeric_Target = 2,
    Completed_Tasks = 3,
    Average_Milestone_Progress = 4,
    Not_Measured = 5
}

let map: {id: number; name: string}[] = [];

for(var n in GoalProgressMeasurements) {
    if (typeof GoalProgressMeasurements[n] === 'number') {
        map.push({id: <any>GoalProgressMeasurements[n], name: n});
    }
}

console.log(map);

参考:https://www.typescriptlang.org/docs/handbook/enums.html