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?
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
}
简单的解决方案。您可以使用以下函数将Enum转换为对象数组。
buildGoalProgressMeasurementsArray(): Object[] {
return Object.keys(GoalProgressMeasurements)
.map(key => ({ id: GoalProgressMeasurements[key], name: key }))
}
如果你需要去掉下划线,我们可以像下面这样使用regex:
buildGoalProgressMeasurementsArray(): Object[] {
return Object.keys(GoalProgressMeasurements)
.map(key => ({ id: GoalProgressMeasurements[key], name: key.replace(/_/g, ' ') }))
}
另一种方法是使用ES8 Object.entries
export enum Weeks {
MONDAY = 1,
TUESDAY= 2,
WEDNESDAY = 3,
THURSDAY = 4,
FRIDAY = 5,
SATURDAY=6,
SUNDAY=7,
}
function convertEnumToArray(){
const arrayObjects = []
// Retrieve key and values using Object.entries() method.
for (const [propertyKey, propertyValue] of Object.entries(Weeks)) {
// Ignore keys that are not numbers
if (!Number.isNaN(Number(propertyKey))) {
continue;
}
// Add keys and values to array
arrayObjects.push({ id: propertyValue, name: propertyKey });
}
console.log(arrayObjects);
}
将产生以下内容:
[
{ id: 1, name: 'MONDAY' },
{ id: 2, name: 'TUESDAY' },
{ id: 3, name: 'WEDNESDAY' },
{ id: 4, name: 'THURSDAY' },
{ id: 5, name: 'FRIDAY' },
{ id: 6, name: 'SATURDAY' },
{ id: 7, name: 'SUNDAY' }
]
无耻地从这个博客偷来的
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。