ios - Firebase 数据库索引路径

Question

我正在尝试使用此函数从 firebase 检索数据，但我没有获取所有数据:

 func retrieveVideos(_ completionBlock: @escaping (_ success: Bool, _ error: Error?) -> ()) {
    let userMessagesRef = DataService.instance.REF_ARTISTARTS.child(Auth.auth().currentUser!.uid)

    userMessagesRef.observe(.childAdded, with: { [weak self] (snapshot) in

        if let snapshot = snapshot.children.allObjects as? [DataSnapshot] {

print("SNAPSHOT: (snapshot.count)") = 12

        }
        guard let strongSelf = self else {return}

        guard let dictionary = snapshot.value as? [String: AnyObject] else {
            completionBlock(false, nil)
            return
        }
        var arts = [Art?]()
        if let art = ArtViewModelController.parse(dictionary) {
            arts.append(art)

            print(arts.count) = 1

        }
        strongSelf.viewModels = ArtViewModelController.initViewModels(arts)
        completionBlock(true, nil)

    }) { (error: Error) in
        completionBlock(false, error)
    }
}



var viewModelsCount: Int {
    return viewModels.count
}


func viewModel(at index: Int) -> ArtViewModel? {
    guard index <= 0 && index < viewModelsCount else { return nil }
    return viewModels[index]
}

private extension ArtViewModelController {

static func parse(_ dictionary: [String: Any]) -> Art? {
    let artID = dictionary["artID"] as? String ?? ""
    let imgUrl = dictionary["imageUrl"] as? String ?? ""
    let title = dictionary["title"] as? String ?? ""
    let description = dictionary["description"] as? String ?? ""
    let price = dictionary["price"] as? NSNumber ?? 0
    let type = dictionary["type"] as? String ?? ""
    let height = dictionary["height"] as? NSNumber ?? 0
    let width = dictionary["width"] as? NSNumber ?? 0
    let postDate = dictionary["postDate"] as? NSNumber ?? 0
    return Art(artID: artID, imgUrl: imgUrl, price: price, title: title, description: description, type: type, height: height, width: width, postDate: postDate)
}


static func initViewModels(_ arts: [Art?]) -> [ArtViewModel?] {
    print("SECOND VIDEO COUNT: \(arts.count)")
    return arts.map { art in
        if let art = art {
            return ArtViewModel(art: art)
        } else {
            return nil
        }
    }
}

我的问题是我的 index.count 总是等于 1 但它应该等于 12。

原代码如下:

 func retrieveUsers(_ completionBlock: @escaping (_ success: Bool, _ error: NSError?) -> ()) {
    let urlString = "http://localhost:3000/users"
    let session = URLSession.shared

    guard let url = URL(string: urlString) else {
        completionBlock(false, nil)
        return
    }
    let task = session.dataTask(with: url) { [weak self] (data, response, error) in
        guard let strongSelf = self else { return }
        guard let data = data else {
            completionBlock(false, error as NSError?)
            return
        }
        let error = NSError.createError(0, description: "JSON parsing error")
        if let jsonData = try? JSONSerialization.jsonObject(with: data, options: .allowFragments) as? [[String: AnyObject]] {
            guard let jsonData = jsonData else {
                completionBlock(false,  error)
                return
            }
            var users = [User?]()
            for json in jsonData {
                if let user = UserViewModelController.parse(json) {
                    users.append(user)
                }
            }

            strongSelf.viewModels = UserViewModelController.initViewModels(users)
            completionBlock(true, nil)
        } else {
            completionBlock(false, error)
        }
    }
    task.resume()
}

所以我正在尝试做同样的事情，但使用 Firebase。如果您需要更多详细信息，请直接询问!

快照打印:

    SNAPSHOT: Optional({
    description = "Yes ";
    height = 87;
    imageUrl = "https://firebasestorage.googleapis.com/v0/b/medici-b6f69.appspot.com/o/Art%2F4bjurh5FFNOUb2D4oHGfRqEm7Il2%2FB6E2A9F0-C409-4732-B6D9-14382E6796F5?alt=media&token=32992b9c-4a08-456d-8950-119f681b4cdc";
    postDate = 1498921599547;
    price = 23;
    private = 0;
    title = "Yes ";
    type = Modern;
    userUID = 4bjurh5FFNOUb2D4oHGfRqEm7Il2;
    width = 71;
})
SNAPSHOT: Optional({
    artHeight = 85;
    artWidth = 123;
    description = "Yes ";
    height = 85;
    imageUrl = "https://firebasestorage.googleapis.com/v0/b/medici-b6f69.appspot.com/o/Art%2F4bjurh5FFNOUb2D4oHGfRqEm7Il2%2F16280189-5AEA-47CB-9251-C95635FFE56C?alt=media&token=8198df4e-da8c-4883-b278-fc7c14730f69";
    postDate = 1498921623601;
    price = 23;
    private = 0;
    title = "blacks don\U2019t Crack ";
    type = Abstract;
    userUID = 4bjurh5FFNOUb2D4oHGfRqEm7Il2;
    width = 123;
})
SNAPSHOT: Optional({
    artHeight = 81;
    artWidth = 11;
    description = "Yes ";
    height = 81;
    imageUrl = "https://firebasestorage.googleapis.com/v0/b/medici-b6f69.appspot.com/o/Art%2F4bjurh5FFNOUb2D4oHGfRqEm7Il2%2F305FDE5C-1C5C-4ABD-B4A1-4FA224421202?alt=media&token=fcba57df-e252-47c2-be92-7836bd97e6fe";
    postDate = 1502242913081;
    price = 23;
    private = 0;
    title = "Title ";
    type = type;
    userUID = 4bjurh5FFNOUb2D4oHGfRqEm7Il2;
    width = 118;
})
SNAPSHOT: Optional({
    description = "Hey ";
    height = 82;
    imageUrl = "https://firebasestorage.googleapis.com/v0/b/medici-b6f69.appspot.com/o/Art%2F4bjurh5FFNOUb2D4oHGfRqEm7Il2%2F04B00727-2AE4-41E3-BCA3-3980182C7F67?alt=media&token=cc1d6a92-1625-453c-bf1f-2ec84d6df51a";
    postDate = 1503341277594;
    price = 23;
    private = 0;
    title = "Title ";
    type = Modern;
    userUID = 4bjurh5FFNOUb2D4oHGfRqEm7Il2;
    width = 124;
})




   DIC: ["height": 87, "private": 0, "width": 71, "postDate": 1498921599547, "description": Yes , "title": Yes , "imageUrl": https://firebasestorage.googleapis.com/v0/b/medici-b6f69.appspot.com/o/Art%2F4bjurh5FFNOUb2D4oHGfRqEm7Il2%2FB6E2A9F0-C409-4732-B6D9-14382E6796F5?alt=media&token=32992b9c-4a08-456d-8950-119f681b4cdc, "userUID": 4bjurh5FFNOUb2D4oHGfRqEm7Il2, "price": 23, "type": Modern]
DIC: ["artWidth": 123, "height": 85, "private": 0, "artHeight": 85, "description": Yes , "postDate": 1498921623601, "width": 123, "imageUrl": https://firebasestorage.googleapis.com/v0/b/medici-b6f69.appspot.com/o/Art%2F4bjurh5FFNOUb2D4oHGfRqEm7Il2%2F16280189-5AEA-47CB-9251-C95635FFE56C?alt=media&token=8198df4e-da8c-4883-b278-fc7c14730f69, "title": blacks don’t Crack , "price": 23, "type": Abstract, "userUID": 4bjurh5FFNOUb2D4oHGfRqEm7Il2]
DIC: ["artWidth": 11, "height": 81, "private": 0, "artHeight": 81, "description": Yes , "postDate": 1502242913081, "width": 118, "imageUrl": https://firebasestorage.googleapis.com/v0/b/medici-b6f69.appspot.com/o/Art%2F4bjurh5FFNOUb2D4oHGfRqEm7Il2%2F305FDE5C-1C5C-4ABD-B4A1-4FA224421202?alt=media&token=fcba57df-e252-47c2-be92-7836bd97e6fe, "title": Title , "price": 23, "type": type, "userUID": 4bjurh5FFNOUb2D4oHGfRqEm7Il2]
DIC: ["height": 82, "private": 0, "width": 124, "postDate": 1503341277594, "description": Hey , "title": Title , "imageUrl": https://firebasestorage.googleapis.com/v0/b/medici-b6f69.appspot.com/o/Art%2F4bjurh5FFNOUb2D4oHGfRqEm7Il2%2F04B00727-2AE4-41E3-BCA3-3980182C7F67?alt=media&token=cc1d6a92-1625-453c-bf1f-2ec84d6df51a, "userUID": 4bjurh5FFNOUb2D4oHGfRqEm7Il2, "price": 23, "type": Modern]

Answer 1

在调用 ArtViewModelController.parse(dictionary) 之前，能否附上 print(dictionary) 和 print(snapshot.value) 的输出？

var arts = [Art?]()
print(dictionary)      // -> output #1
print(snapshot.value)  // -> output #2
if let art = ArtViewModelController.parse(dictionary) {
    arts.append(art)
[...]