使用SQLite的MissingMethodException

Question

我试图让SQLite在本地存储一些信息，到目前为止，我遇到了一个恼人的问题:每当我调用sqlite函数CreateTable时，它都会返回一个异常。

下面是一个例外：

Unhandled Exception:
System.MissingMethodException: Method not found: string SQLitePCL.raw.sqlite3_column_name(SQLitePCL.sqlite3_stmt,int).

下面是我用来使其跨平台的接口：

public interface IDataBase
{
    SQLiteConnection GetConnection();
}

Android实现：

[assembly: Dependency(typeof(DataBase))]
namespace MyNameSpace.Droid
{
    public class DataBase : IDataBase
    {
        public DataBase() { }
        public SQLiteConnection GetConnection()
        {
            var fileName = "DataBase.db3";
            string docsPath = System.Environment.GetFolderPath(System.Environment.SpecialFolder.Personal);
            string path = Path.Combine(docsPath, fileName);
            var conn = new SQLiteConnection(path);
            return conn;
        }
    }
}

还有一个iOs版本：

[assembly: Dependency(typeof(DataBase))]
namespace MyNameSpace.iOS
{
    public class DataBase : IDataBase
    {
        public DataBase() { }
        public SQLiteConnection GetConnection()
        {
            var fileName = "DataBase.db3";
            var docPath = Environment.GetFolderPath(Environment.SpecialFolder.Personal);
            var libraryPath = Path.Combine(docPath, "..", "Library");
            var path = Path.Combine(libraryPath, fileName);
            var conn = new SQLiteConnection(path);
            return conn;
        }
    }
}

然后我有我的表类型：

namespace MyNameSpace.DataBase
{
     public class MacroCategoria
     {
        [PrimaryKey]
        public int ID { get; set; }
        public string descrizione { get; set; }

        public MacroCategoria() { }

    }
}

获取第一个元素的DataBase控制器和I方法：

namespace MyNameSpace.DataBase
{
    public class DBController
    {
        static object locker = new object();
        SQLiteConnection database;

        public DBController()
        {
            database = DependencyService.Get<IDataBase>().GetConnection();
            if (database != null)
            {
                database.CreateTable<MacroCategoria>();
                database.Insert(new MacroCategoria() { ID = 0, descrizione = "Description" });
            }
        }

        public MacroCategoria getFirstMacro()
        {
            lock (locker)
            {
                if (database.Table<MacroCategoria>().Count() == 0)
                    return null;
                else
                    return database.Table<MacroCategoria>().First();
            }

        }

    }
}

在App类中调用：

public partial class App : Application
{
    static DBController dbController;
    public App()
    {
        InitializeComponent();
        DependencyService.Register<MockDataStore>();
        MainPage = new MainPage();
    }

    [...Other Default Methods...]

    public static DBController DBController
    {
        get
        {
            if(dbController == null)
            {
                dbController = new DBController();
            }
            return dbController;
        }
    }
}

最后，在我的mainPage中，我有一个函数，它应该获取第一个元素：

private void CartIcon_Clicked(object sender, EventArgs e)
{
    try
    {
        App.DBController.getFirstMacro();

    } catch(Exception ex) { throw; }
}

Answer 1

看起来我只需要添加SQLitePCL.Raw包。