在Swift中从实时数据库Firebase中获取数据

Question

我有一些数据存在于实时数据库． 但是当我获取数据时，它会给我错误。

我有这样的数据在实时数据库:

"Transaction_By_Date": {
"Ahmad_24-03-2023 17:38:15": {
"28-03-2023": {
"total_amount_receive": 10000,
"total_amount_send": 20000,
"transactions": {
"-NRZfbq2xYhHF-v1beKC": {
"amount": 20000,
"date": "28-03-2023 01:06:53",
"detail": "Sending",
"image": "no image",
"type": "Send"
},
"-NRZfs_i1RWHQ-8xYYa1": {
"amount": 10000,
"date": "28-03-2023 01:07:40",
"detail": "Detail",
"image": "no image",
"type": "Receive"
}
},
"29-03-2023": {
"total_amount_receive": 5000,
"total_amount_send": 0,
"transactions": {
"-NRZfxRoPkLQxOJfCyGq": {
"amount": 5000,
"date": "28-03-2023 01:08:24",
"detail": "Received",
"image": "no image",
"type": "Receive"
}
}
}
}
}
}

我曾尝试像这样使用firebasedatabasesswift获取此响应．我的代码是:

import FirebaseDatabase
import FirebaseDatabaseSwift
func getEntries(userId: String) {
Database.database().reference().child("Transaction_By_Date").child(userId).observe(.value) { snapshot in

guard let children = snapshot.children.allObjects as? [DataSnapshot] else {
return
}

let transactionsData = children.compactMap { dictionary in

do {

var transaction = try dictionary.data(as: TransactionByDate.self)
transaction.id = dictionary.ref.key
return transaction

} catch let error {
print(error.localizedDescription)
return TransactionByDate()
}
}

print(transactionsData)
}
}

这是我的TransactionByDate模型:

struct TransactionByDate: Identifiable, Codable {

var id: String?
var total_amount_sent: Int?
var total_amount_receive: Int?
var transactions: [Transactions]?
}
struct Transactions: Identifiable, Codable {

var id: String?
var amount: Int?
var date: String?
var detail: String?
var image: String?
var type: String?
}

当这个函数被调用时。我得到这个错误:

数据无法读取，因为它不是正确的格式。

谁能告诉我我做错了什么?我该怎么做才能让它起作用呢?

Answer 1

A Joakim指出，JSON中的transactions节点是一个字典，而不是一个数组。当您在Firebase中通过调用childByAutoId创建列表时，这是正常的。

要修复这个错误，声明你的transactions属性为一个字典:

var transactions: [String: Transactions]?

了解更多关于为什么Firebase不使用数组的列表，我建议阅读最佳实践:数组在Firebase..