爲什麼將數據保存到SQLite數據庫不適用於Swift 2？

我使用的是SQLite.swift，我使用SQLite.swift演示中的這些代碼。爲什麼將數據保存到SQLite數據庫不適用於Swift 2？

import UIKit 
import SQLite 

class ViewController: UIViewController { 
    override func viewDidLoad() { 
     super.viewDidLoad() 
     let db = try! Connection() 
     let users = Table("users") 
     let id = Expression<Int64>("id") 
     let email = Expression<String>("email") 
     let name = Expression<String?>("name") 
     try! db.run(users.create { t in 
      t.column(id, primaryKey: true) 
      t.column(email, unique: true, check: email.like("%@%")) 
      t.column(name) 
     }) 
     try! db.run(users.insert(email <- "[email protected]")) 
     for user in db.prepare(users) { 
      print("id: \(user[id]), email: \(user[email])") 
     } 
    } 
}

我第一次運行它，則輸出是：

("SELECT * FROM \"users\"", []) 
id: 1, email: [email protected]

然後我除去線17（try! db.run(users.insert(email <- "[email protected]"))）並再次運行，調試器輸出改變爲：

("SELECT * FROM \"users\"", [])

看起來像[email protected]沒有保存到數據庫。那麼我做錯了什麼？或者如何將它保存到SQLite數據庫中？

P.S.我正在使用Xcode 7 beta 5，Swift 2.0

來源

2015-08-20 David

請檢查數據庫。該記錄在數據庫中可用？ –

我不知道位於@iAshish的數據庫位於何處 – David

您已經給出了將數據庫存儲在文檔目錄路徑的路徑嗎？ @大衛？ –

viewDidLoad首先創建表，然後插入。

當表已經存在時，我不知道表create函數的行爲，但如果它不會在您身上拋出任何錯誤，它可能會再次重新創建表。如果是這種情況，在插入註釋後調用viewDidLoad之後，可能會得到一個新的空白表。

嘗試更改邏輯，確保每次都不重新創建表。

來源

2015-08-20 04:55:53 MirekE

let db = try! Connection()

創建內存數據庫，您可以從API文檔，請參見：

/// Initializes a new SQLite connection. 
/// 
/// - Parameters: 
/// 
/// - location: The location of the database. Creates a new database if it 
///  doesn’t already exist (unless in read-only mode). 
/// 
///  Default: `.InMemory`. 
/// 
/// - readonly: Whether or not to open the database in a read-only state. 
/// 
///  Default: `false`. 
/// 
/// - Returns: A new database connection. 
public init(_ location: Location = .InMemory, readonly: Bool = false) throws

的數據不保存到一個文件，該數據庫總是最初空。

對於持續數據庫，使用

/// Initializes a new connection to a database. 
/// 
/// - Parameters: 
/// 
/// - filename: The location of the database. Creates a new database if 
///  it doesn’t already exist (unless in read-only mode). 
/// 
/// - readonly: Whether or not to open the database in a read-only state. 
/// 
///  Default: `false`. 
/// 
/// - Throws: `Result.Error` iff a connection cannot be established. 
/// 
/// - Returns: A new database connection. 
public convenience init(_ filename: String, readonly: Bool = false) throws

代替，例如

// Compute file path for database in Documents directory: 
let docsDir = NSSearchPathForDirectoriesInDomains(.DocumentDirectory, .UserDomainMask, true).last! 
let dbPath = (docsDir as NSString).stringByAppendingPathComponent("database.sqlite") 

do { 
    let db = try Connection(dbPath) 
    // ... use database 

} catch (error) { 
    // Could not create or open database, print error 
}

來源

2015-08-20 05:11:32

你可能有這樣的事情（當然其他人可以提高代碼）：

創建表格模型：

class TUsers { 
static let TABLE_NAME : String = 「users」 
static let ID = Expression<Int64>("id") 
static let EMAIL = Expression<String>(「email」) 
static let NAME = Expression<String>(「name」) 

class func addUser(email : String!, name : String!) -> Bool{ 

    let users = Table(TABLE_NAME) 

    do { 

     try DBHelper.instance.db.run(users.insert(
      TUsers.EMAIL <- email, 
      TUsers.NAME <- name 
     )) 

     return true 
    } catch { 
     print("Insert failed") 
     return false 
    } 
} 

class func getAllUsers() -> [User] { // you must create the model user 
    let users = Table(TUsers.TABLE_NAME) 

    let query = users.select(*) 
     //.filter(TUsers.EMAIL == 「[email protected]」) 

    var listOfUsers : [Users] = [] 

    for user in DBHelper.instance.db.prepare(query) { 
     // Do whatever you need to instantiate the model User 


     listOfUsers.append(User(email: users[TUsers.EMAIL], name: users[TUsers.NAME]) 

    } 

    return listOfUsers 
} 
}

創建數據庫幫手

class DBHelper { 

static let instance = DBHelper() 

var db : Connection 

init() { 
    do { 
     self.db = try Connection("\(Util.getDBPath())/db.sqlite3") 
     createTablesIfNotExists() 
    } catch { 
     print("Could not create a connection to database") 
    } 
} 

func createTablesIfNotExists() { 

    let users = Table(TUsers.TABLE_NAME) 
    do { 
     try db.run(logs.create(ifNotExists: true) { t in 
       t.column(TUsers.ID, primaryKey: true) 
       t.column(TUsers.EMAIL) 
       t.column(TUsers.NAME) 
     }) 
    } catch { 
     print(「Could not create table users」) 
    } 
} 
}

最後（在這裏你不需要導入SQLite的）。

class ViewController: UIViewController { 
override func viewDidLoad() { 
    super.viewDidLoad() 

    TUsers.addUser(「[email protected]」, 「John Capuchon」) 

    let users = TUsers.getAllUsers() 

    for user in users { 
     // do something 
    } 
}

}

來源

2015-10-08 13:02:14 Kingslayerpy

爲什麼將數據保存到SQLite數據庫不適用於Swift 2？

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