如何在Nest Js中返回实体类型的promise

Question

我正在编写一个函数，该函数使用给定类型的数据返回promise。我的实体名称是Groups，我想返回一个组Groups[]的数组这是我的功能

async filterGroupsByAvailableSpots (groups: Groups[] ) :Promise<Groups[]> {
let groupsAvailableToMatch : Groups[] = [] ;

let searchAvailableGroupsLoop = new Promise((resolve, reject) => {
groups.forEach((group, index, array) => {
this.getStudentsByActiveGroup (group.id)
.then((students) => {
//If the group have spots to match
if (students.length < 6) {
groupsAvailableToMatch.push(group)
}
// Stop FLag    
if (index === array.length -1) {
resolve(groupsAvailableToMatch);
} 
})
});
});
return searchAvailableGroupsLoop;
}

但我在退货承诺中遇到错误

let searchAvailableGroupsLoop: Promise<unknown>
Type '{}' is missing the following properties from type 'Groups[]': length, pop, push, concat, and 26 more.ts(2740)

Answer 1

我认为TS无法推断返回变量的类型，请尝试在创建promise 时指定类型

let searchAvailableGroupsLoop = new Promise<Groups[]>((resolve, reject) => {

Answer 2

您需要解决每个案例的Promise。如果在您的组数组中没有"0"；停止标志"；你的诺言定为{}。因此，如果更适合您的需求，请使用空数组进行解决，或者使用错误进行拒绝。

async filterGroupsByAvailableSpots (groups: Groups[] ) :Promise<Groups[]> {
let groupsAvailableToMatch : Groups[] = [] ;
let searchAvailableGroupsLoop = new Promise((resolve, reject) => {
groups.forEach((group, index, array) => {
this.getStudentsByActiveGroup (group.id)
.then((students) => {
//If the group have spots to match
if (students.length < 6) {
groupsAvailableToMatch.push(group)
}
// Stop FLag    
if (index === array.length -1) {
resolve(groupsAvailableToMatch);
} 
})
});
resolve([]); // add this line or reject("Error");
});
return searchAvailableGroupsLoop;

}