Typescript 基于泛型参数返回函数签名
我有一个函数Typescript 基于泛型参数返回函数签名,typescript,typescript-typings,typescript2.0,typescript1.8,typescript-generics,Typescript,Typescript Typings,Typescript2.0,Typescript1.8,Typescript Generics,我有一个函数createRequest: 函数createRequest(方法:string,路径:string){ 返回函数resourceApiCall(){ //…附加逻辑 返回httpCall(路径、方法) } } 返回一个我想调用的函数resourceApiCall,如: const fetchUsers=createRequest('GET','/users')) 等待fetchUsers({createdAfter:new Date()}) 我还想做一些类似的事情: const
createRequest
:
函数createRequest(方法:string,路径:string){
返回函数resourceApiCall(){
//…附加逻辑
返回httpCall(路径、方法)
}
}
返回一个我想调用的函数resourceApiCall
,如:
const fetchUsers=createRequest('GET','/users'))
等待fetchUsers({createdAfter:new Date()})
我还想做一些类似的事情:
const fetchPayment=createRequest('GET','/payments'))
等待fetchPayment('id',{createdAfter:new Date()})
我的问题是,如何将定义传递给createRequest
,以便fetchUsers
和fetchPayment
在IDE中显示正确的函数参数和返回值(任何类型的检查都正确)
我相信我需要做一些事情,比如:
支付接口{
(id:string,{createdAfter:Date}):承诺
}
const fetchPayment=createRequest('GET','/payments')
但理想情况下,我想做如下工作:
const fetchPayment=createRequest('GET','/payments'))
函数createRequest(方法:string,路径:string){
返回函数resourceApiCall(…args:args){
//…附加逻辑
返回httpCall(路径、方法)
}
}
您可以将别名和重载组合在一起以使其正常工作。基本上,将这些参数别名为字符串文字类型,然后为函数提供多个签名。然后,TypeScript可以根据传入的参数推断createRequest
的返回类型
type UserPath = '/users';
type PaymentPath = '/payment';
type CreatedAfter = {
createdAfter: Date;
};
function createRequest(
HttpVerb: string,
target: UserPath
): (id: string, date: CreatedAfter) => Promise<{ id: string }>;
function createRequest(
HttpVerb: string,
target: PaymentPath
//I'm just guessing the return type here
): (date: CreatedAfter) => Promise<{ id: string }[]>;
function createRequest(HttpVerb: string, target: UserPath | PaymentPath): any {
//your function implementation doesn't have to be like this, this is just so
//this example is fully working
if (target === '/users') {
return async function(date) {
return { id: '1' };
};
} else if (target === '/payment') {
return async function(id, date) {
return [{ id: '1' }];
};
}
}
//this signature matches your fetchUsers signature
const fetchUsers = createRequest('GET', '/users');
//this signature matches your fetchPayment signature
const fetchPayment = createRequest('GET', '/payment');
type UserPath='/users';
键入PaymentPath='/payment';
类型CreatedAfter={
createdAfter:日期;
};
函数createRequest(
HttpVerb:string,
目标:用户路径
):(id:string,date:CreatedAfter)=>Promise;
函数createRequest(
HttpVerb:string,
目标:支付路径
//我只是猜测这里的返回类型
):(日期:CreatedAfter)=>承诺;
函数createRequest(HttpVerb:string,target:UserPath | PaymentPath):任意{
//您的函数实现不必是这样的,这就是这样
//这个例子完全有效
如果(目标=='/users'){
返回异步函数(日期){
返回{id:'1'};
};
}否则,如果(目标==='/付款'){
返回异步函数(id、日期){
返回[{id:'1'}];
};
}
}
//此签名与您的fetchUsers签名匹配
const fetchUsers=createRequest('GET','/users');
//此签名与您的付款签名匹配
const fetchPayment=createRequest('GET','/payment');
总之,这将允许
createRequest
函数根据传递的第二个参数返回具有正确签名的函数,按住ctrl+f键并搜索“重载”以了解有关重载的更多信息。您可以这样继续:
// some interfaces you expect httpCall to return
interface User {
name: string;
age: number;
}
interface Payment {
id: string;
}
// a mapping of request paths to the function signatures
// you expect to return from createRequest
interface Requests {
"/users": (clause: { createdAfter: Date }) => Promise<Array<User>>;
"/payments": (id: string, clause: { createdAfter: Date }) => Promise<Payment>;
}
// a dummy httpCall function
declare function httpCall<R>(path: string, method: string, payload: any): R;
// for now only GET is supported, and the path must be one of keyof Requests
function createRequest<P extends keyof Requests>(method: "GET", path: P) {
return (function resourceApiCall(
...args: Parameters<Requests[P]> // Parameters<F> is the arg tuple of function type F
): ReturnType<Requests[P]> { // ReturnType<F> is the return type of function type F
return httpCall<ReturnType<Requests[P]>>(path, method, args);
} as any) as Requests[P]; // assertion to clean up createRequest signature
}
async function foo() {
const fetchUsers = createRequest("GET", "/users");
const users = await fetchUsers({ createdAfter: new Date() }); // User[]
const fetchPayment = createRequest("GET", "/payments");
const payment = await fetchPayment("id", { createdAfter: new Date() }); // Payment
}
然后你可以为你的用户制作一个模块:
请求/user.ts
export interface Requests extends Record<keyof Requests, (...args: any[]) => any> {
// empty here, but merge into this
}
// a dummy httpCall function
declare function httpCall<R>(path: string, method: string, payload: any): R;
// for now only GET is supported, and the path must be one of keyof Requests
export function createRequest<P extends keyof Requests>(method: "GET", path: P) {
return (function resourceApiCall(
...args: Parameters<Requests[P]> // Parameters<F> is the arg tuple of function type F
): ReturnType<Requests[P]> {
// ReturnType<F> is the return type of function type F
return httpCall<ReturnType<Requests[P]>>(path, method, args);
} as any) as Requests[P]; // assertion to clean up createRequest signature
}
export interface User {
name: string;
age: number;
}
declare module './requests' {
interface Requests {
"/users": (clause: { createdAfter: Date }) => Promise<Array<User>>;
}
}
export interface Payment {
id: string;
}
declare module './requests' {
interface Requests {
"/payments": (id: string, clause: { createdAfter: Date }) => Promise<Payment>;
}
}
import { createRequest } from './Requests/requests';
import './Requests/user'; // maybe not necessary
import './Requests/payment'; // maybe not necessary
async function foo() {
const fetchUsers = createRequest("GET", "/users");
const users = await fetchUsers({ createdAfter: new Date() }); // User[]
const fetchPayment = createRequest("GET", "/payments");
const payment = await fetchPayment("id", { createdAfter: new Date() }); // Payment
}
等等。最后,用户可以通过导入createRequest
和user
和payment
模块调用这些模块(如果其中包含代码,则需要在模块中运行):
测试.ts
export interface Requests extends Record<keyof Requests, (...args: any[]) => any> {
// empty here, but merge into this
}
// a dummy httpCall function
declare function httpCall<R>(path: string, method: string, payload: any): R;
// for now only GET is supported, and the path must be one of keyof Requests
export function createRequest<P extends keyof Requests>(method: "GET", path: P) {
return (function resourceApiCall(
...args: Parameters<Requests[P]> // Parameters<F> is the arg tuple of function type F
): ReturnType<Requests[P]> {
// ReturnType<F> is the return type of function type F
return httpCall<ReturnType<Requests[P]>>(path, method, args);
} as any) as Requests[P]; // assertion to clean up createRequest signature
}
export interface User {
name: string;
age: number;
}
declare module './requests' {
interface Requests {
"/users": (clause: { createdAfter: Date }) => Promise<Array<User>>;
}
}
export interface Payment {
id: string;
}
declare module './requests' {
interface Requests {
"/payments": (id: string, clause: { createdAfter: Date }) => Promise<Payment>;
}
}
import { createRequest } from './Requests/requests';
import './Requests/user'; // maybe not necessary
import './Requests/payment'; // maybe not necessary
async function foo() {
const fetchUsers = createRequest("GET", "/users");
const users = await fetchUsers({ createdAfter: new Date() }); // User[]
const fetchPayment = createRequest("GET", "/payments");
const payment = await fetchPayment("id", { createdAfter: new Date() }); // Payment
}
好的,希望这能再次有所帮助。这是一个巨大的帮助@jcalz!有没有一种方法可以让我在哪里内联声明预期的参数和返回类型,而不是使用接口请求
?我不确定我是否理解。。。您可以改用类型别名(type Requests={”/users):(子句:{createdAfter:Date}=>Promise;…
)但是你可能想给它起个名字,因为请求
在签名和实现中多次出现,一遍又一遍地写那种类型可能会很烦人。如果我更了解你的用例,我可能会提出一个建议。你为什么不想要一个请求
接口或类型呢?我会的因为我正在创建一个内部客户机sdk(http调用的抽象),所以我需要将各个类型定义放在同一个位置。我遵循大多数大型公司使用的模式,特别是stripe。在本例中,他们有一个Charges
资源,可以简单地创建一个端点。我希望我的模式与此完全相同+内联预期的参数和端点的返回值。我的createRequest
相当于St再次感谢您的帮助!因此,我建议保留请求
界面,并使用它将端点添加到请求
?让我看看是否可以重构上面的代码来演示…更新了我的答案,希望它能帮到更多。