在 SwiftUI 中读取带有子节点的 Firebase 实时数据库父节点的问题答案

【问题标题】：Issue reading Firebase realtime database parent node with children nodes in SwiftUI在 SwiftUI 中读取带有子节点的 Firebase 实时数据库父节点的问题
【发布时间】：2020-09-16 01:44:51
【问题描述】：

我有以下 Firebase 实时数据库结构：

posts: {
    user1_uid: {
        -Kfm0p2EMcrpN8XcLOR5: {
            created_at: 1490119356.786182,
            image_height: 374.9999999999999,
            image_url: "ttps://firebasestorage.googleapis.com/v0/b/mak...",
            like_count: 4,
            poster: {
                uid: user1_uid,
                username: "testuser"
            }
        },
        -KgGuLttcC3PJbD8pWAT: { ... },
        -KgLo0OrineV8l3_K9gK: { ... }
    },
    user2_uid: { ... },
    user3_uid: { ... }
}

使用以下 'Post' 结构：

init?(snapshot: DataSnapshot) {
        
    guard
        
        let value = snapshot.value as? [String: AnyObject],
        
        let uID = value["poster/uid"] as? String,
        let userName = value["poster/username"] as? String,
        
        let text = value["text"] as? String,
        let likes = value["likes"] as? Int,
        let created = value["created"] as? String,
        
        let iHeight = value["imageheight"] as? Double,
        let imageName = value["imagename"] as? String
        
    else {
        
        print("************************************************")
        print("PostStore init?(snapshot: DataSnapshot) ERROR!!!")
        print("************************************************")
        
        return nil
    
    }
    
    self.id = snapshot.key
    
    self.uID = uID!
    self.userName = userName!
    
    self.text = text!
    self.created = created!
    self.likes = likes!
    
    self.iHeight = iHeight!
    self.imageName = imageName!
    
}

当我运行代码时，我总是打印出else portion of the statement executed with the error？！

我认为问题在于以下代码：

let uID = value["poster/uid"] as? String,
let userName = value["poster/username"] as? String,

因为它有一个子节点。我不确定如何访问该节点的信息？

有人可以帮忙吗！

*********更新******

另一方面，我将如何写入我目前拥有的数据库：

func toAnyObject() -> Any {                  

    return [                          
        "poster/username": userName,             
        "poster/uid": uID,             
        "text": text,             
        "created": created,              
        "likes": likes,             
        "imageheight": iHeight,             
        "imageName": imageName                                    
    ]

}

当使用/ char 崩溃时，我如何在写入 Firebase 数据库时考虑子节点“海报”。

【问题讨论】：

标签： firebase firebase-realtime-database swiftui

【解决方案1】：

所以基于我的两 (2) 部分问题；最初它只是一 (1) 个问题，但在 Asperi 为我最初阅读的问题提供了一个很好的答案后，写作部分变成了问题后变成了两 (2) 个。

我的答案包含了他上面的答案，然后我修改了其余部分以满足对 Firebase 的读写。

struct Post: Identifiable {

    var id: String
    var profile: Profile?
    var uID: String
    var userName: String
    var text: String
    var created: String
    var likes: Int
    var iHeight: Double
    var imageName: String

    init(id: String, profile: Profile, text: String, created: String, likes: Int, iHeight: Double, imageName: String ) {

        self.id = id
        self.profile = profile
        self.userName = profile.userName
        self.uID = profile.uID
        self.text = text
        self.created = created
        self.likes = likes
        self.iHeight = iHeight
        self.imageName = imageName

    }

    init?(snapshot: DataSnapshot) {

        guard
        
            let value = snapshot.value as? [String: AnyObject],
            let poster = value["poster"] as? [String: AnyObject], 
        
            let uID = poster["uid"] as? String,
            let userName = poster["username"] as? String,
            let text = value["text"] as? String,
            let likes = value["likes"] as? Int,
            let created = value["created"] as? String,
            let iHeight = value["imageheight"] as? Double,
            let imageName = value["imagename"] as? String
        
        else {
        
            return nil
        
        }
    
        self.id = snapshot.key
        self.uID = uID
        self.userName = userName
        self.text = text
        self.created = created
        self.likes = likes
        self.iHeight = iHeight
        self.imageName = imageName
    
    }

    func toAnyObject() -> Any {
    
        return [
            "poster": profile!.toAnyObject(), 
            "text": text,
            "created": created,
            "likes": likes,
            "imageheight": iHeight,
            "imagename": imageName
        ]
    
    }

}

struct Profile: Codable {

    let uID: String
    let userName: String

    func toAnyObject() -> Any {

        return [
            "uid": uID,
            "username": userName
        ]

    }

}

希望这对其他人有所帮助。

【讨论】：