Typescript 从泛型类中的类型参数创建新对象
我正在尝试在泛型类中创建类型参数的新对象。 在我的类Typescript 从泛型类中的类型参数创建新对象,typescript,generics,Typescript,Generics,我正在尝试在泛型类中创建类型参数的新对象。 在我的类视图中,我有两个作为类型参数传递的泛型类型的对象列表,但是当我尝试创建新的TGridView()时,TypeScript说: 找不到符号“TGridView” 代码如下: module AppFW { // Represents a view export class View<TFormView extends FormView, TGridView extends GridView> { // T
视图
中,我有两个作为类型参数传递的泛型类型的对象列表,但是当我尝试创建新的TGridView()
时,TypeScript说:
找不到符号“TGridView”
代码如下:
module AppFW {
// Represents a view
export class View<TFormView extends FormView, TGridView extends GridView> {
// The list of forms
public Forms: { [idForm: string]: TFormView; } = {};
// The list of grids
public Grids: { [idForm: string]: TGridView; } = {};
public AddForm(formElement: HTMLFormElement, dataModel: any, submitFunction?: (e: SubmitFormViewEvent) => boolean): FormView {
var newForm: TFormView = new TFormView(formElement, dataModel, submitFunction);
this.Forms[formElement.id] = newForm;
return newForm;
}
public AddGrid(element: HTMLDivElement, gridOptions: any): GridView {
var newGrid: TGridView = new TGridView(element, gridOptions);
this.Grids[element.id] = newGrid;
return newGrid;
}
}
}
模块AppFW{
//表示一个视图
导出类视图{
//表格清单
公共窗体:{[idForm:string]:TFormView;}={};
//网格列表
公共网格:{[idForm:string]:TGridView;}={};
公共AddForm(formElement:HTMLFormElement,dataModel:any,submitFunction?:(e:SubmitFormViewEvent)=>boolean):FormView{
var newForm:TFormView=newtformview(formElement、dataModel、submitFunction);
this.Forms[formElement.id]=newForm;
返回新表单;
}
public AddGrid(元素:htmldevelment,gridOptions:any):GridView{
var newGrid:TGridView=newtgridview(元素,gridOptions);
this.Grids[element.id]=newGrid;
返回新网格;
}
}
}
我可以从泛型类型创建对象吗?由于已编译的JavaScript已删除所有类型信息,因此不能使用
t
新建对象
您可以通过将类型传递到构造函数中,以非泛型的方式实现这一点
class TestOne {
hi() {
alert('Hi');
}
}
class TestTwo {
constructor(private testType) {
}
getNew() {
return new this.testType();
}
}
var test = new TestTwo(TestOne);
var example = test.getNew();
example.hi();
您可以使用泛型扩展此示例,以收紧类型:
class TestBase {
hi() {
alert('Hi from base');
}
}
class TestSub extends TestBase {
hi() {
alert('Hi from sub');
}
}
class TestTwo<T extends TestBase> {
constructor(private testType: new () => T) {
}
getNew() : T {
return new this.testType();
}
}
//var test = new TestTwo<TestBase>(TestBase);
var test = new TestTwo<TestSub>(TestSub);
var example = test.getNew();
example.hi();
类TestBase{
你好(){
警报(‘基地高’);
}
}
类TestSub扩展了TestBase{
你好(){
警报(“来自sub的Hi”);
}
}
类test2{
构造函数(私有测试类型:new()=>T){
}
getNew():T{
返回新的this.testType();
}
}
//var测试=新的测试二(TestBase);
var测试=新测试二(TestSub);
var-example=test.getNew();
例如:hi();
要在泛型代码中创建新对象,需要通过其构造函数引用该类型。因此,与其写这封信:
function activatorNotWorking<T extends IActivatable>(type: T): T {
return new T(); // compile error could not find symbol T
}
功能激活器不工作(类型:T):T{
return new T();//编译错误找不到符号T
}
你需要这样写:
function activator<T extends IActivatable>(type: { new(): T ;} ): T {
return new type();
}
var classA: ClassA = activator(ClassA);
函数激活器(类型:{new():T;}):T{
返回新类型();
}
var classA:classA=激活剂(classA);
见这个问题:
所有类型信息在JavaScript端被擦除,因此您不能像@Sohnee states那样更新,但我更希望将类型参数传递给构造函数:
class A {
}
class B<T> {
Prop: T;
constructor(TCreator: { new (): T; }) {
this.Prop = new TCreator();
}
}
var test = new B<A>(A);
export class VW_MyData {
public RawColumn: string;
public TransformedColumn: string;
public constructor(init?: Partial<VW_MyData>) {
Object.assign(this, init);
this.TransformedColumn = this.transform(this.RawColumn);
}
protected transform(input: string): string {
return `Transformation of ${input}!`;
}
}
class Sample {
public innerField: string;
constructor(data: Partial<Sample>) {
this.innerField = data.innerField;
}
}
export class GenericWithParams<TType> {
public innerItem: TType;
constructor(data: Partial<GenericWithParams<TType>>, private typePrototype: new (i: Partial<TType>) => TType) {
this.innerItem = this.factoryMethodOnModel(data.innerItem);
}
private factoryMethodOnModel = (item: Partial<TType>): TType => {
return new this.typePrototype(item);
};
}
const instance = new GenericWithParams<Sample>({ innerItem : { innerField: 'test' }}, Sample);
A类{
}
B类{
道具:T;
构造函数(TCreator:{new():T;}){
this.Prop=new TCreator();
}
}
var测试=新的B(A);
导出抽象类formBase扩展基类{
受保护项={}为T;
}
它的对象将能够接收任何参数,但是,类型T只是一个typescript引用,不能通过构造函数创建。也就是说,它不会创建任何类对象代码> 它通常是有效的 编辑1:
导出类EntityCollection{
可变:可编辑实体[]=[];
不可变:T[]=[];
编辑(索引:编号){
this.mutable[index].entity=Object.assign({},this.immutable[index]);
}
}
我试图从基类中实例化泛型。上面的例子都不适合我,因为它们需要一个具体的类型来调用工厂方法
在对此进行了一段时间的研究之后,我无法在网上找到解决方案,我发现这似乎是可行的
protected activeRow: T = {} as T;
作品:
activeRow: T = {} <-- activeRow now equals a new object...
没有完全回答这个问题,但是,对于这类问题有一个很好的库:(尽管它对泛型类型不起作用,因为它们在运行时并不存在(这里所有的工作都是用类名(类构造函数))完成的) 例如:
import {Type, plainToClass, deserialize} from "class-transformer";
export class Foo
{
@Type(Bar)
public nestedClass: Bar;
public someVar: string;
public someMethod(): string
{
return this.nestedClass.someVar + this.someVar;
}
}
export class Bar
{
public someVar: string;
}
const json = '{"someVar": "a", "nestedClass": {"someVar": "B"}}';
const optionA = plainToClass(Foo, JSON.parse(json));
const optionB = deserialize(Foo, json);
optionA.someMethod(); // works
optionB.someMethod(); // works
我知道晚了,但是@TadasPa的答案可以通过使用
TCreator: new() => T
而不是
TCreator: { new (): T; }
所以结果应该是这样的
class A {
}
class B<T> {
Prop: T;
constructor(TCreator: new() => T) {
this.Prop = new TCreator();
}
}
var test = new B<A>(A);
A类{
}
B类{
道具:T;
构造函数(TCreator:new()=>T){
this.Prop=new TCreator();
}
}
var测试=新的B(A);
我这样做是为了保留类型信息:
class Helper {
public static createRaw<T>(TCreator: { new (): T; }, data: any): T
{
return Object.assign(new TCreator(), data);
}
public static create<T>(TCreator: { new (): T; }, data: T): T
{
return this.createRaw(TCreator, data);
}
}
...
it('create helper', () => {
class A {
public data: string;
}
class B {
public data: string;
public getData(): string {
return this.data;
}
}
var str = "foobar";
var a1 = Helper.create<A>(A, {data: str});
expect(a1 instanceof A).toBeTruthy();
expect(a1.data).toBe(str);
var a2 = Helper.create(A, {data: str});
expect(a2 instanceof A).toBeTruthy();
expect(a2.data).toBe(str);
var b1 = Helper.createRaw(B, {data: str});
expect(b1 instanceof B).toBeTruthy();
expect(b1.data).toBe(str);
expect(b1.getData()).toBe(str);
});
类助手{
公共静态createRaw(TCreator:{new():T;},数据:any):T
{
返回Object.assign(新的TCreator(),数据);
}
公共静态创建(TCreator:{new():T;},数据:T):T
{
返回此.createRaw(TCreator,data);
}
}
...
它('create helper',()=>{
甲级{
公共数据:字符串;
}
B类{
公共数据:字符串;
public getData():字符串{
返回此.data;
}
}
var str=“foobar”;
var a1=Helper.create(A,{data:str});
expect(A.toBeTruthy()的a1实例);
expect(a1.数据),toBe(str);
var a2=Helper.create(A,{data:str});
expect(A.toBeTruthy()的a2实例);
expect(a2.数据),toBe(str);
var b1=Helper.createRaw(B,{data:str});
expect(B.toBeTruthy()的b1实例);
expect(b1.数据),toBe(str);
expect(b1.getData()).toBe(str);
});
我参加聚会要迟到了,但这就是我工作的方式。对于阵列,我们需要做一些技巧:
public clone<T>(sourceObj: T): T {
var cloneObj: T = {} as T;
for (var key in sourceObj) {
if (sourceObj[key] instanceof Array) {
if (sourceObj[key]) {
// create an empty value first
let str: string = '{"' + key + '" : ""}';
Object.assign(cloneObj, JSON.parse(str))
// update with the real value
cloneObj[key] = sourceObj[key];
} else {
Object.assign(cloneObj, [])
}
} else if (typeof sourceObj[key] === "object") {
cloneObj[key] = this.clone(sourceObj[key]);
} else {
if (cloneObj.hasOwnProperty(key)) {
cloneObj[key] = sourceObj[key];
} else { // insert the property
// need create a JSON to use the 'key' as its value
let str: string = '{"' + key + '" : "' + sourceObj[key] + '"}';
// insert the new field
Object.assign(cloneObj, JSON.parse(str))
}
}
}
return cloneObj;
}
公共克隆(sourceObj:T):T{
var cloneObj:T={}as T;
for(sourceObj中的var键){
if(sourceObj[key]数组实例){
if(sourceObj[key]){
//首先创建一个空值
让str:string='{'+key+':''}';
assign(cloneObj,JSON.parse(str))
//用实际值更新
cloneObj[key]=sourceObj[key];
}否则{
Object.assign(cloneObj,[]
}
}else if(sourceObj[key]=“object”的类型){
cloneObj[key]=this.clone(sourceObj[key]);
}否则{
if(cloneObj.hasOwnProperty(键)){
cloneObj[key]=sourceObj[key];
}否则
TCreator: { new (): T; }
class A {
}
class B<T> {
Prop: T;
constructor(TCreator: new() => T) {
this.Prop = new TCreator();
}
}
var test = new B<A>(A);
class Helper {
public static createRaw<T>(TCreator: { new (): T; }, data: any): T
{
return Object.assign(new TCreator(), data);
}
public static create<T>(TCreator: { new (): T; }, data: T): T
{
return this.createRaw(TCreator, data);
}
}
...
it('create helper', () => {
class A {
public data: string;
}
class B {
public data: string;
public getData(): string {
return this.data;
}
}
var str = "foobar";
var a1 = Helper.create<A>(A, {data: str});
expect(a1 instanceof A).toBeTruthy();
expect(a1.data).toBe(str);
var a2 = Helper.create(A, {data: str});
expect(a2 instanceof A).toBeTruthy();
expect(a2.data).toBe(str);
var b1 = Helper.createRaw(B, {data: str});
expect(b1 instanceof B).toBeTruthy();
expect(b1.data).toBe(str);
expect(b1.getData()).toBe(str);
});
public clone<T>(sourceObj: T): T {
var cloneObj: T = {} as T;
for (var key in sourceObj) {
if (sourceObj[key] instanceof Array) {
if (sourceObj[key]) {
// create an empty value first
let str: string = '{"' + key + '" : ""}';
Object.assign(cloneObj, JSON.parse(str))
// update with the real value
cloneObj[key] = sourceObj[key];
} else {
Object.assign(cloneObj, [])
}
} else if (typeof sourceObj[key] === "object") {
cloneObj[key] = this.clone(sourceObj[key]);
} else {
if (cloneObj.hasOwnProperty(key)) {
cloneObj[key] = sourceObj[key];
} else { // insert the property
// need create a JSON to use the 'key' as its value
let str: string = '{"' + key + '" : "' + sourceObj[key] + '"}';
// insert the new field
Object.assign(cloneObj, JSON.parse(str))
}
}
}
return cloneObj;
}
let newObj: SomeClass = clone<SomeClass>(someClassObj);
export class TableComponent<T> {
public Data: T[] = [];
public constructor(
protected type: new (value: Partial<T>) => T
) { }
protected insertRow(value: Partial<T>): void {
let row: T = new this.type(value);
this.Data.push(row);
}
}
export class MyDataComponent extends TableComponent<VW_MyData> {
public constructor(protected service: DataService) {
super(VW_MyData);
this.query();
}
protected query(): void {
this.service.post(...).subscribe((json: VW_MyData[]) => {
for (let item of json) {
this.insertRow(item);
}
}
}
}
export class VW_MyData {
public RawColumn: string;
public TransformedColumn: string;
public constructor(init?: Partial<VW_MyData>) {
Object.assign(this, init);
this.TransformedColumn = this.transform(this.RawColumn);
}
protected transform(input: string): string {
return `Transformation of ${input}!`;
}
}
class Sample {
public innerField: string;
constructor(data: Partial<Sample>) {
this.innerField = data.innerField;
}
}
export class GenericWithParams<TType> {
public innerItem: TType;
constructor(data: Partial<GenericWithParams<TType>>, private typePrototype: new (i: Partial<TType>) => TType) {
this.innerItem = this.factoryMethodOnModel(data.innerItem);
}
private factoryMethodOnModel = (item: Partial<TType>): TType => {
return new this.typePrototype(item);
};
}
const instance = new GenericWithParams<Sample>({ innerItem : { innerField: 'test' }}, Sample);