[英]Typescript Conditional Types Not Figuring Out Type
Assuming the given type:假设给定类型:
export declare type MongoManagerFilter<T> = {
[P in keyof T]?: (P extends keyof T ? T[P] : any);
};
When trying to specify the filter:尝试指定过滤器时:
update.$setOnInsert.createdAt = new Date();
I get this error:我收到此错误:
Type 'Date' is not assignable to type '"createdAt" extends keyof T ? T[keyof T & "createdAt"] : any'.ts(2322)
But if I change the filter to this it works:但是,如果我将过滤器更改为此它可以工作:
export declare type MongoManagerFilter<T> = {
[P in keyof T]?: any;
};
Why does the conditional statement not actually figure out the type?为什么条件语句实际上并没有弄清楚类型? It's just keeping the code as the type.
它只是将代码保留为类型。
I know the filter doesn't make sense how it is, I have another type instead of keyof T
to catch dot notation, but I am having the same issue with conditional statements not figuring out the actual type.我知道过滤器没有意义,我有另一种类型而不是
keyof T
来捕获点表示法,但是我遇到了同样的问题,条件语句无法确定实际类型。
interface CollectionDocument {
_id?: string;
createdAt: Date;
}
type PathImpl<T, Key extends keyof T> =
Key extends string
? T[Key] extends Record<string, any>
? `${Key}.${PathImpl<T[Key], Exclude<keyof T[Key], keyof Date | keyof Object | keyof string> & string>}`
| `${Key}.${Exclude<keyof T[Key], keyof Date | keyof Object | keyof string> & string}`
: never
: never;
type Path<T> = keyof T | PathImpl<T, keyof T>;
type PathValue<T, P extends Path<T>> =
P extends `${infer Key}.${infer Rest}`
? Key extends keyof T
? Rest extends Path<T[Key]>
? PathValue<T[Key], Rest>
: never
: never
: P extends keyof T
? T[P]
: any;
export declare type MongoManagerFilter<T> = {
[P in Path<T>]?: PathValue<T, P>;
};
export class MongoManagerCollection<T extends CollectionDocument> {
constructor() {}
updateOne(filter: MongoManagerFilter<T>) {
// THIS DOES NOT WORK
filter._id = '';
filter.createdAt = new Date();
}
}
// THIS WORKS
let testModel = new MongoManagerCollection<CollectionDocument>();
testModel.updateOne({_id: 'test', createdAt: new Date()});
Generic type T
in:通用类型
T
在:
export class MongoManagerCollection<T extends CollectionDocument> {
constructor() { }
updateOne(filter: MongoManagerFilter<T>) {
// THIS DOES NOT WORK
filter._id = '';
filter.createdAt = new Date();
}
}
is a black box.是一个黑匣子。
filter._id
is resolved as a non evaluated conditional type. filter._id
被解析为非评估条件类型。 Treat it as a non called function.将其视为非称为 function。 Function which is has never been called does not return any value.
从未调用过的 Function 不返回任何值。 Same is with
filter._id
. filter._id
也是如此。 filter._id
coresponds to this: filter._id
对应于此:
type PathValue<T, P extends Path<T>> =
P extends `${infer Key}.${infer Rest}`
? Key extends keyof T
? Rest extends Path<T[Key]>
? PathValue<T[Key], Rest>
: never
: never
: P extends keyof T ////////////////////////////////////////////////
? T[P] // Property is resolved as a conditional type //
: any; ///////////////////////////////////////////////
As you might have noticed, filter._id
is P extends keyof T? T[P]: any
您可能已经注意到,
filter._id
是P extends keyof T? T[P]: any
P extends keyof T? T[P]: any
instead of just T[P]
. P extends keyof T? T[P]: any
而不仅仅是T[P]
。
There is a workaround.有一种解决方法。 You can use
T[P & keyof T]
instead of conditional type
.您可以使用
T[P & keyof T]
代替conditional type
。 See working example:请参阅工作示例:
interface CollectionDocument {
_id?: string;
createdAt: Date;
}
type PathImpl<T, Key extends keyof T> =
Key extends string
? T[Key] extends Record<string, any>
? `${Key}.${PathImpl<T[Key], Exclude<keyof T[Key], keyof Date | keyof Object | keyof string> & string>}`
| `${Key}.${Exclude<keyof T[Key], keyof Date | keyof Object | keyof string> & string}`
: never
: never;
type Path<T> = keyof T | PathImpl<T, keyof T>;
type PathValue<T, P extends Path<T>> =
P extends `${infer Key}.${infer Rest}`
? Key extends keyof T
? Rest extends Path<T[Key]>
? PathValue<T[Key], Rest>
: never
: never
: T[P & keyof T]
export declare type MongoManagerFilter<T> = {
[P in Path<T>]?: PathValue<T, P>;
};
export class MongoManagerCollection<T extends CollectionDocument> {
constructor() { }
updateOne(filter: MongoManagerFilter<T>) {
filter._id = ''; // ok
filter.createdAt = new Date(); // ok
filter.createdAt = 'sdf'; // expected error
}
}
// THIS WORKS
let testModel = new MongoManagerCollection<CollectionDocument>();
testModel.updateOne({ _id: 'test', createdAt: new Date() });
If you are interested in path
implementation, you can take a look at this answer, this utility and/or my article .如果您对
path
实现感兴趣,可以查看此答案、 此实用程序和/或我的文章。
I don't know MongoDB api and the requirements of your types so I can't say whether they need to be modified or not.我不知道 MongoDB api 和你的类型的要求,所以我不能说它们是否需要修改。
Also, you can get rid of generic:此外,您可以摆脱泛型:
export class MongoManagerCollection {
constructor() { }
updateOne(filter: MongoManagerFilter<CollectionDocument>) {
filter._id = ''; // ok
filter.createdAt = new Date(); // ok
}
}
// THIS WORKS
let testModel = new MongoManagerCollection();
testModel.updateOne({ _id: 'test', createdAt: new Date() });
but I don't think this is what you want.但我不认为这是你想要的。
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