使用Decodable在Firestore中获取对象和文档ID [英] Using Decodable to get the object and document ID with Firestore

问题描述

我有一个简单的User类，其中包含以下字段:

I have a simple User class which has the following fields:

{ 
  "localIdentifier": "xyc9870",
  "isOnline": false,
  "username": "ZS"
}

我想使用Swift的Decodable轻松地将QueryDocumentSnapshot转换为类型安全的Swift结构.我还想确保从QueryDocumentSnapshot获取documentID以便以后更新对象.

I want to use Swift's Decodable to easily turn the QueryDocumentSnapshot into a type safe Swift struct. I also want to make sure that I get the documentID from the QueryDocumentSnapshot for updating the object later.

这是我目前用于解码的内容，但是显然它错过了documentId

This is what I'm currently using to decode but obviously it misses the documentId

struct User: Decodable {

    let localIdentifier: String
    let username: String
    let isOnline: Bool

}

在这里愿意帮忙.谢谢！

Would love a hand here. Thanks!

推荐答案

我为自己编写了一个小的便捷扩展，将documentID引入了data JSON，然后可以使用下面的简单struct

I wrote myself a small convenience extension that just brings the documentID into the data JSON and then I can use the simple struct below

extension QueryDocumentSnapshot {

    func prepareForDecoding() -> [String: Any] {
        var data = self.data()
        data["documentId"] = self.documentID

        return data
    }

}

使用以下代码进行解码:

Decode using:

struct User: Decodable {

    let documentId: String
    let localIdentifier: String
    let username: String
    let isOnline: Bool

}

if let user = try? JSONDecoder().decode(User.self, fromJSONObject: doc.prepareForDecoding()) {
    ...
}

我的JSONDecoder扩展名

extension JSONDecoder {
    func decode<T>(_ type: T.Type, fromJSONObject object: Any) throws -> T where T: Decodable {
        return try decode(T.self, from: try JSONSerialization.data(withJSONObject: object, options: []))
    }
}

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