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

我是这样解的

        const listKeys = Object.keys(TripStatus); //TripStatus is enum type
        const numOfItem = listKeys.length/2;
        for(let i=0; i<numOfItem; i++){
          this.listStatus.push({
            id: listKeys[i],
            name: listKeys[numOfItem+i]
          })
        }

其他回答

我不建议在需要枚举条目列表的情况下使用TS enum。

在运行时,Enum是作为对象实现的,但它只在这种情况下工作:

enum X {
  Z = 'z',
  F = 'f'
};

console.log(Object.values(X))
console.log(Object.keys(X))
>>>
[LOG]: ["z", "f"] 
[LOG]: ["Z", "F"] 

在这种情况下,它与陷阱一起工作(TS让你通过它的数值访问值):

enum X {
  Z,
  F
};

console.log(Object.values(X))
console.log(Object.keys(X))
>>>
[LOG]: ["Z", "F", 0, 1] 
[LOG]: ["0", "1", "Z", "F"] 

因此,根据Enum定义,任何你写在Enum上循环的函数都将工作/失败。这是…不好的。

我的结论是:Enum不是被设计用来作为对象的。如果你需要访问键和值集合,请使用const而不是enum:

const Enumed = {
    X: 1,
    Y: 2
}

Typescript将控制对象键的存在,你将能够使用object。钥匙等,以安全一致的方式。

TS:

仅适用于短(<10个元素)enum

const keys = Object.keys(Enum).filter((el: string) => el.length > 1)
console.log(keys)

Object.keys()将返回一个包含['0','1','2','enumElement1', 'enumElement2', enumElement3']的数组 Filter()获取每个元素并检查其长度(因为字符串),并从结果数组中排除所有数字

由于具有字符串值的枚举不同于具有数字值的枚举,因此最好从@user8363解决方案中过滤非数字。

这里是你如何从enum字符串中获取值,数字混合:

/ /帮助 export const StringIsNotNumber = value => isNaN(Number(value)) === true; //将枚举转换为数组 导出函数enumToArray(枚举){ 返回种(enumme) .filter (StringIsNotNumber) .map(key => enumme[key]); }

你可以这样做:

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

export class GoalProgressMeasurement {
    constructor(public goalProgressMeasurement: GoalProgressMeasurements, public name: string) {
    }
}

export var goalProgressMeasurements: { [key: number]: GoalProgressMeasurement } = {
    1: new GoalProgressMeasurement(GoalProgressMeasurements.Percentage, "Percentage"),
    2: new GoalProgressMeasurement(GoalProgressMeasurements.Numeric_Target, "Numeric Target"),
    3: new GoalProgressMeasurement(GoalProgressMeasurements.Completed_Tasks, "Completed Tasks"),
    4: new GoalProgressMeasurement(GoalProgressMeasurements.Average_Milestone_Progress, "Average Milestone Progress"),
    5: new GoalProgressMeasurement(GoalProgressMeasurements.Not_Measured, "Not Measured"),
}

你可以这样使用它:

var gpm: GoalProgressMeasurement = goalProgressMeasurements[GoalProgressMeasurements.Percentage];
var gpmName: string = gpm.name;

var myProgressId: number = 1; // the value can come out of drop down selected value or from back-end , so you can imagine the way of using
var gpm2: GoalProgressMeasurement = goalProgressMeasurements[myProgressId];
var gpmName: string = gpm.name;

您可以根据需要使用对象的附加属性扩展GoalProgressMeasurement。我将这种方法用于每个应该是包含多个值的对象的枚举。

我不认为顺序是可以保证的,否则就很容易切片Object的后半部分。条目的结果和映射来自那里。

上述答案的唯一(非常小的)问题是

字符串和数字之间有很多不必要的类型转换。 当一次迭代同样干净有效时,条目将迭代两次。

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

function enumToList<T extends StandardEnum> (enm: T) : { id: number; description: string }[] {
    return Object.entries(enm).reduce((accum, kv) => {
        if (typeof kv[1] === 'number') {
            accum.push({ id: kv[1], description: kv[0] })
        }
        return accum
    }, []) // if enum is huge, perhaps pre-allocate with new Array(entries.length / 2), however then push won't work, so tracking an index would also be required
}