如何在xamarin表單中使用SQLite-Net-PCL？

Question

我在我的項目中安裝了SQLite-net-pcl軟件包。現在我想用它來進行簡單的CRUD操作。問題是我讀的所有文檔都讓我感到困惑。任何人都可以提示我在Xamarin.Forms中執行CRUD操作的正確步驟，以接受值表單並將其存儲在數據庫中？

Answer 1

我在我的工作應用程序中使用此方法。

1. 安裝SQLite-net-pcl

2. 我使用異步方法。爲了排除鎖，我使用這個類：

   public sealed class AsyncLock 
   { 
       private readonly SemaphoreSlim _semaphore = new SemaphoreSlim(1, 1); 
       private readonly Task<IDisposable> _releaser; 
   
   public AsyncLock() 
   { 
       _releaser = Task.FromResult((IDisposable)new Releaser(this)); 
   } 
   
   public Task<IDisposable> LockAsync() 
   { 
       var wait = _semaphore.WaitAsync(); 
       return wait.IsCompleted ? 
        _releaser : 
        wait.ContinueWith((_, state) => (IDisposable)state, 
        _releaser.Result, CancellationToken.None, 
        TaskContinuationOptions.ExecuteSynchronously, TaskScheduler.Default); 
   } 
   
   private sealed class Releaser : IDisposable 
   { 
       private readonly AsyncLock m_toRelease; 
   
       internal Releaser(AsyncLock toRelease) 
       { 
        m_toRelease = toRelease; 
       } 
   
       public void Dispose() 
       { 
        m_toRelease._semaphore.Release(); 
       } 
   } 
   } 
   

3. 創建域（表）：

   //base class for table 
   public class Entity 
   { 
       [PrimaryKey, AutoIncrement] 
       public int Id { get; set; } 
   } 
   
   //your table 
   public class Data :Entity 
   { 
       public string Prop1 {get;set;} 
       ...... 
   } 
   
   public class Data2 :Entity 
   { 
       public string Prop2 {get;set;} 
       ...... 
   } 
   

4. 創建倉庫：

   public class DataRepository 
   { 
       private SQLiteAsyncConnection _db; 
       private static readonly AsyncLock Mutex = new AsyncLock(); 
   
       public async Task CreateDatabaseAsync(string path) 
       { 
       using (await Mutex.LockAsync().ConfigureAwait(false)) 
       { 
        _db= new SQLiteAsyncConnection(path); 
        await _db.CreateTableAsync<Data>(); 
        //create other tables 
       } 
   
       public async Task Save<T>(T entity) where T : Entity, new() 
       { 
        using (await Mutex.LockAsync().ConfigureAwait(false)) 
        { 
        await _db.InsertAsync(entity); 
        } 
       } 
   
       public async Task Delete(Entity item) 
       { 
        using (await Mutex.LockAsync().ConfigureAwait(false)) 
        { 
        await _db.DeleteAsync(item); 
        } 
       } 
   
       public async Task Update<T>(T entity) where T : Entity, new() 
       { 
        using (await Mutex.LockAsync().ConfigureAwait(false)) 
        { 
         await _db.UpdateAsync(entity); 
        } 
       }   
       ........ 
       //other base method 
       } 
   

5. 在App類中爲DataRepository創建靜態字段。在你的代碼中使用這個 App.Repo。

   App.Repo.Save(new Data 
         { 
          ... 
         }) ; 
   

這是利用的簡化示例。