Typescript装饰程序+;反映元数据
我正在使用属性装饰器Typescript装饰程序+;反映元数据,typescript,reflect-metadata,Typescript,Reflect Metadata,我正在使用属性装饰器字段,它将其“键”推送到字段反映元数据属性: export function Field(): PropertyDecorator { return (target, key) => { const fields = Reflect.getMetadata('fields', target) || []; if (!fields.includes(key)) { fields.push(key)
字段
,它将其“键”推送到字段
反映元数据属性:
export function Field(): PropertyDecorator {
return (target, key) => {
const fields = Reflect.getMetadata('fields', target) || [];
if (!fields.includes(key)) {
fields.push(key)
}
Reflect.defineMetadata('fields', fields, target)
}
}
然后我有一个抽象基类表单
,它访问getter附件中的元数据:
abstract class Form {
get fields() {
return Reflect.getMetadata('fields', this) || [];
}
}
到目前为止,我已经能够成功地使用它来区分表单字段和其他类属性。考虑这些类:
abstract class UserForm extends Form {
@Field()
public firstName: string
@Field()
public lastName: string
get fullName() {
return this.firstName + ' ' + this.lastName;
}
}
class AdminForm extends UserForm {
@Field()
roles: string[]
}
const form = new AdminForm()
console.log(form.fields)
// ['roles', 'firstName', 'lastName']
当我将姐妹类定义为AdminForm
-MemberForm
时,就会出现问题。当有多个子类存在于表单
中时,字段
getter似乎返回所有字段:
class MemberForm extends UserForm {
@Field()
memberSince: Date;
}
const form = new AdminForm()
console.log(form.fields)
// ['roles', 'firstName', 'lastName', 'memberSince'] <--!!!
class MemberForm扩展了UserForm{
@字段()
成员自:日期;
}
const form=new AdminForm()
console.log(form.fields)
//['roles'、'firstName'、'lastName'、'memberSince']问题是getMetadata
沿着原型链向下,并且总是返回在基类型上定义的内容(因为它首先被分配)。只有在添加新字段时,以及在获取字段时,才需要使用getownmatadata
获取当前类的数组字段,而在获取字段时,则需要沿着属性链遍历以获取所有基类字段
这应该起作用:
import 'reflect-metadata'
export function Field(): PropertyDecorator {
return (target, key) => {
const fields = Reflect.getOwnMetadata('fields', target) || [];
if (!fields.includes(key)) {
fields.push(key)
}
Reflect.defineMetadata('fields', fields, target)
}
}
abstract class Form {
get fields() {
let fields = []
let target = Object.getPrototypeOf(this);
while(target != Object.prototype) {
let childFields = Reflect.getOwnMetadata('fields', target) || [];
fields.push(...childFields);
target = Object.getPrototypeOf(target);
}
return fields;
}
}
abstract class UserForm extends Form {
@Field()
public firstName!: string
@Field()
public lastName!: string
get fullName() {
return this.firstName + ' ' + this.lastName;
}
}
class AdminForm extends UserForm {
@Field()
roles!: string[]
}
const form1 = new AdminForm()
console.log(form1.fields) // ['roles', 'firstName', 'lastName']
class MemberForm extends UserForm {
@Field()
memberSince!: Date;
}
const form2 = new MemberForm()
console.log(form2.fields) // ["memberSince", "firstName", "lastName"]
有趣!如果我在属性装饰器上将getMetadata
更改为getownmatadata
,那么我将在字段上获得['roles']
。那么,你走上产业链是什么意思?哇!太棒了!谢谢!