如何以Xamarin形式使用SQLite-Net-PCL? [英] How to use SQLite-Net-PCL in xamarin forms?

问题描述

我已经在项目中安装了SQLite-net-pcl软件包.现在，我想将其用于简单的CRUD操作.事实是，我阅读的所有文档都使我感到困惑.有人可以提示我在Xamarin.Forms中执行CRUD操作以接受值表单Entry并将其存储在数据库中的适当步骤吗?

I have installed SQLite-net-pcl package in my project. And now I want to use it for simple CRUD operations. The thing is that all the documentation I read was confusing to me. Can anyone hint me for the proper steps to perform a CRUD operation in Xamarin.Forms to accept a value form Entry and store it in database?

推荐答案

我在工作的应用中使用此方法.

I use this method in my working app.

1. 安装 SQLite-net-pcl

我使用异步方法.为了排除锁，我使用了此类:

I use async methods. To exclude locks, I use this class:

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();
    }
}
}

创建域(表):

Create domains(tables):

 //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;}  
    ......   
 } 

创建存储库:

Create repository:

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
  }

1. 在您的App类中为DataRepository创建静态字段.用这个 App.Repo输入您的代码.

1. Create static field for DataRepository in your App class. Use this App.Repo in your code.

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

这是使用的简化示例.

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