Question

我在实体框架拦截方面遇到了一些问题。在我的场景中，我想在选择sql statemant由sql服务器执行之前对其进行修改。使用拦截时可以看到命令，但是是否有一种简单的方法来获取为此脚本生成的实体类型？我无法在拦截方法中找到有关目标实体的任何信息。

我从主项目中创建了一个非常简单的改编。

实体：

[Table("Empty", Schema = "Base")]
public class EmptyBase
{
    [Key]
    [Column("ID", Order = 0)]
    public Guid ID { get; set; }
}

[Table("SoftDele", Schema ="Base")]
public class SoftDeleteBase : EmptyBase
{
    [Column("IsDeleted")]
    public bool IsDeleted { get; set; }

    [Column("IsActive")]
    public bool IsActive { get; set; }
}

[Table("ToolTip", Schema = "Base")]
public class ToolTipBase : SoftDeleteBase
{
    [Column("ToolTip")]
    public string ToolTip { get; set; }
}

[Table("Test1", Schema = "Data")]
public class Test1 : ToolTipBase
{
    [Column("Test1Content")]
    public string Test1Content { get; set; }
}

[Table("Test2", Schema = "Data")]
public class Test2 : SoftDeleteBase
{
    [Column("Test2Content")]
    public string Test2Content { get; set; }
}

DbContext和拦截器：

    public class DatabaseCTX : DbContext
    {
     public DatabaseCTX() : base(@"Data Source=localhost;Initial Catalog = SQL_Interception; Integrated Security = True")
    {
        //Database.SetInitializer(new DropCreateDatabaseAlways<DatabaseCTX>());
    }

    protected override void OnModelCreating(DbModelBuilder modelBuilder)
    {
        base.OnModelCreating(modelBuilder);
    }

    public DbSet<Models.EmptyBase> EmptyBases { get; set; }
    public DbSet<Models.SoftDeleteBase> SoftDeleteBases { get; set; }
    public DbSet<Models.Test1> Test1s { get; set; }
    public DbSet<Models.Test2> Test2s { get; set; }
    public DbSet<Models.ToolTipBase> ToolTipBases { get; set; }
}

public class EFInterception : DbConfiguration
{
    public EFInterception()
    {
        this.AddInterceptor(new EFCommandInterceptor());
        this.AddInterceptor(new EFCommandTreeInterceptor());
    }
}

public class EFCommandTreeInterceptor : IDbCommandTreeInterceptor
{
    public void TreeCreated(DbCommandTreeInterceptionContext interceptionContext)
    {
        //throw new NotImplementedException();
    }
}

public class EFCommandInterceptor : IDbCommandInterceptor
{
    public void NonQueryExecuted(DbCommand command, DbCommandInterceptionContext<int> interceptionContext) 
    {
        //throw new NotImplementedException();
    }

    public void NonQueryExecuting(DbCommand command, DbCommandInterceptionContext<int> interceptionContext)
    {
        //throw new NotImplementedException();
    }

    public void ReaderExecuted(DbCommand command, DbCommandInterceptionContext<DbDataReader> interceptionContext)
    {
        //throw new NotImplementedException();
    }

    public void ReaderExecuting(DbCommand command, DbCommandInterceptionContext<DbDataReader> interceptionContext)
    {
        //throw new NotImplementedException();
    }

    public void ScalarExecuted(DbCommand command, DbCommandInterceptionContext<object> interceptionContext)
    {
        //throw new NotImplementedException();
    }

    public void ScalarExecuting(DbCommand command, DbCommandInterceptionContext<object> interceptionContext)
    {
        //throw new NotImplementedException();
    }
}

在我的测试应用程序窗口中至少有一个小代码：

public partial class MainWindow : Window
{        
    Controls.DatabaseCTX databaseCTX;
    public MainWindow()
    {
        InitializeComponent();
    }

    private void Button_Click(object sender, RoutedEventArgs e)
    {
        databaseCTX = new Controls.DatabaseCTX();
        //MessageBox.Show(typeof(EF_Interception.Controls.)
    }

    private void Button_Click_1(object sender, RoutedEventArgs e)
    {
        if(databaseCTX == null)
            databaseCTX = new Controls.DatabaseCTX();
        databaseCTX.Test1s.Add(new Models.Test1() { ID = Guid.NewGuid(), IsActive = true, Test1Content = "asgsewarasfd asdgasdfgasdf asdfg asdfds", ToolTip = "Nope" });
        databaseCTX.Test2s.Add(new Models.Test2() { ID = Guid.NewGuid(), IsActive = true, Test2Content = "asgsewarasfd asdgasdfgasdf asdfg asdfds"});
        databaseCTX.SaveChanges();
    }

    private void Button_Click_2(object sender, RoutedEventArgs e)
    {
        if (databaseCTX == null)
            databaseCTX = new Controls.DatabaseCTX();
        var a = databaseCTX.Test1s.ToList();
        var b = databaseCTX.Test2s.ToList();
        MessageBox.Show(a.Count.ToString() + "_" + b.Count.ToString());
    }

    private void Button_Click_3(object sender, RoutedEventArgs e)
    {
        if (databaseCTX == null)
            databaseCTX = new Controls.DatabaseCTX();
        var c = databaseCTX.SoftDeleteBases.ToList();
        MessageBox.Show(c.Count.ToString());
    }

问题在于，Button_Click_3-方法中生成的选择脚本还包含所有子表（test1，test2）中的所有字段在这个小例子中，一切工作正常，但是当我在具有60-70个表的Big数据库中使用这种类型的概念时，为基本表生成的Select脚本在SQL服务器上执行起来很复杂。在正常情况下，这没问题，因为我直接与子实体（test1，test2）一起工作，但是当我尝试更改实体的“ IsDeleted”，“ IsActive”或“ ToolTip”属性时遇到问题。

Answer 1

如果要在保存dbcontext之前进行更改，则可以使用SaveChanges方法。

https://exceptionnotfound.net/entity-change-tracking-using-dbcontext-in-entity-framework-6/

在EntityFramework的拦截中获取实体类型

1 个答案: