[英]Typescript: generics type for nested functions
I have looked for answers to this problem but I can not implement them correctly. 我一直在寻找这个问题的答案,但是我无法正确实现它们。 Maybe you can tell me the right way.
也许您可以告诉我正确的方法。
I'll explain: I want to use typescript generics not to use any more 'Any' in my methods. 我将说明:我想使用打字稿泛型而不在我的方法中使用更多的“任何”。
I am writing the code and what I would like to do. 我正在编写代码以及我想做什么。
IN THE COMPONENT: 在组件中:
this.DatabaseService.getCollection <IUser> ('users', 'lastname'). subscribe (loadData =>
{
this.listUser = loadData;
});
when I call getCollection () I will call the following nested methods: 当我调用getCollection()时,我将调用以下嵌套方法:
I want the type (IUser) passed to getCollection () to be forwarded to the nitidicated methods until you reach getCollectionRef () obtaining a return collection of this type: collection 我希望将传递给getCollection()的类型(IUser)转发给已初始化的方法,直到到达getCollectionRef()以获得该类型的返回集合:collection
FILE SERVICE: database.service.ts 文件服务:database.service.ts
getCollection <T> (path: string, sortBy ?: string): Observable <T []>
{
// >>>how do I pass the type (T) to getCollectionSnapshot() ?
return this.getCollectionSnapshot (path, sortBy) .pipe (
map (changes =>
{
return changes.map (change =>
{
const data = change.payload.doc.data ();
const id = change.payload.doc.id;
return {id, ... data};
});
}
));
}
getCollectionSnapshot (path: string, sortBy ?: string): Observable <any []>
{
return this.getCollectionRef (path, sortBy) .snapshotChanges ();
}
getCollectionRef (path: string, sortBy ?: string): AngularFirestoreCollection
{
if (sortBy === undefined)
{
return this.afs.collection (path);
}
else
{
return this.afs.collection (path, ref => ref.orderBy (sortBy));
}
}
Thank you ! 谢谢 ! I hope to fill my gap in generics
我希望填补我在仿制药方面的空白
I am not sure if i understand your problem. 我不确定我是否理解你的问题。 You want to pass the type parameter given for the method getCollection to the methods called within getCollection .
你想传递的方法getCollection到名为内getCollection方法给出的类型参数。 If that's the case would this fit for you:
如果是这样,那么它适合您:
getCollection <T> (path: string, sortBy ?: string): Observable <T []>
{
return this.getCollectionSnapshot<T> (path, sortBy) .pipe (
map (changes =>
{
return changes.map (change =>
{
const data = change.payload.doc.data ();
const id = change.payload.doc.id;
return {id, ... data};
});
}
));
}
getCollectionSnapshot<T> (path: string, sortBy ?: string): Observable <any []>
{
return this.getCollectionRef<T> (path, sortBy) .snapshotChanges ();
}
getCollectionRef<T> (path: string, sortBy ?: string): AngularFirestoreCollection
{
if (sortBy === undefined)
{
return this.afs.collection (path);
}
else
{
return this.afs.collection (path, ref => ref.orderBy (sortBy));
}
}
notice the changes: 注意更改:
getCollectionSnapshot <T> (... getCollectionSnapshot <T> (...
getCollectionRef <T> (... getCollectionRef <T> (...
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