I use entity framework code first to work with my database. I have several tables with different names but same structure, and this tables dynamically appears in database. How could I map EntityFramework to one of that tables at run-time and use data from just like I work this over entities of DbContext?

我首先使用实体​​框架代码来处理我的数据库。我有几个不同名称但结构相同的表,这些表动态地出现在数据库中。我如何在运行时将EntityFramework映射到其中一个表并使用数据,就像我在DbContext的实体上工作一样?

What I've done to make it work:

我做了什么让它工作:

For example, my class what describes structure of dynamically created table is SetElement.

例如,我的类描述了动态创建的表的结构是SetElement。

Here is my context:

这是我的背景:

public class DataContext : DbContext
{
    public DataContext()
        : base("RepositoryConnectionString") { }

    string setElementsTableId; // the name of table that need to be dynamicly mapped to 

    // Enforce model recreating
    public DataContext(string setElementsTableId)
        : this()
    {
        this.setElementsTableId = setElementsTableId;
    }


    /* some other entities */

    public DbSet<Entities.SetElement> SetElements { get; set; } // dynamicly mapped entity


    protected override void OnModelCreating(DbModelBuilder modelBuilder)
    {
        /* come configurations */

        if (!string.IsNullOrEmpty(setElementsTableId))
        {
            modelBuilder.Entity<Entities.SetElement>().Map(x => x.ToTable(setElementsTableId)); // map SetElements property to dynamicly created table
        }
    }
}

How I use this:

我怎么用这个:

public static void AddSetElements(ICollection<SetElement> setElements, string tableId)
    {
     using (ctx = new DataContext(tableId)) // configere DataContext to map tableId table for entity SetElements
       try
       {
           var num = ctx.SetElements.Count();
           ctx.SetElements.AddRange(setElements);
           ctx.SaveChanges();
       }
       catch (Exception e)
       {
       }
 }

I have also some methods to get, udtate and remove data from dynamicly created tables that are same to AddSetElements.

我还有一些方法来获取,udtate和从动态创建的表中删除与AddSetElements相同的数据。

All works just as I wish but only if AddSetElements runs first, because at the first datacontext creating DbContext.OnModelCreating runs and configure all mappings. But next instance creation doesn't call DbContext.OnModelCreating.

所有工作都按照我的意愿工作,但只有当AddSetElements首先运行时,因为在第一个datacontext创建DbContext.OnModelCreating运行并配置所有映射。但是下一个实例创建不会调用DbContext.OnModelCreating。

So, my question is: how to call DbContext.OnModelCreating everytime of creating an instance of DataContext then I use DataContext(string setElementsTableId) to create it?

所以,我的问题是:如何在每次创建DataContext实例时调用DbContext.OnModelCreating然后我使用DataContext(string setElementsTableId)来创建它?

I know, my question is similar to 'dynamic table mapping in EF' but I found nothing in the results.

我知道,我的问题类似于'EF中的动态表映射',但我在结果中找不到任何内容。

By the way. If you know another way to solve my problem, you are welcome.

顺便说说。如果您知道解决问题的另一种方法,欢迎您。

2 个解决方案

public class EntityFrameworkConfiguration: DbConfiguration
{
    public EntityFrameworkConfiguration()
    {
        this.SetModelCacheKey(ctx => new EntityModelCacheKey((ctx.GetType().FullName + ctx.Database.Connection.ConnectionString).GetHashCode()));
    }
}

public class EntityModelCacheKey : IDbModelCacheKey
{
    private readonly int _hashCode;

    public EntityModelCacheKey(int hashCode)
    {
        _hashCode = hashCode;
    }

    public override bool Equals(object other)
    {
        if (other == null) return false;
        return other.GetHashCode() == _hashCode;
    }

    public override int GetHashCode()
    {
        return _hashCode;
    }
}

public class DataContext : DbContext
{

  string setElementsTableId; 

  // use the setElementsTableId as extended property of the 
  // connection string to generate a custom key
  public DataContext(string setElementsTableId)
        : base(ConfigurationManager.ConnectionStrings["RepositoryConnectionString"] 
 + "; Extended Properties=\"setElementsTableId=" + setElementsTableId + "\"")
  {
    this.setElementsTableId = setElementsTableId;
  }

  public DbSet<Entities.SetElement> SetElements { get; set; } 

  protected override void OnModelCreating(DbModelBuilder modelBuilder)
  {
    if (!string.IsNullOrEmpty(setElementsTableId))
    {
        modelBuilder.Entity<Entities.SetElement>().Map(x => x.ToTable(setElementsTableId)); 
    }
  }
}