C# DropCreateDatabaseAlways与重写的上下文。SaveChanges（）

我正在重写DbContext.SaveChanges（），以便在应用程序中实现数据库审核

我的DbContext类如下所示：

public override int SaveChanges()
{
    throw new InvalidOperationException("User Id must be provided for auditing purposes.");
}

public int SaveChanges(bool suppressAudit)
{
    if (suppressAudit)
        return base.SaveChanges();
    else
        throw new InvalidOperationException("User Id must be provided for auditing purposes.");
}

public int SaveChanges(int userId)
{
    foreach(var entity in ChangeTracker.Entries().Where(p=>p.State == EntityState.Added || p.State == EntityState.Deleted || p.State == EntityState.Modified))
    {
        foreach(var auditEntry in GetAuditRecordsForChange(entity,userId))
        {
            Audit.Add(auditEntry);
        }
    }
    return base.SaveChanges();
}

public class ABS4Initializer : DropCreateDatabaseAlways<MyContext>
{        
        protected override void Seed(MyContext context)
        {
            var users = BuildUserData();            
            users.ForEach(u => context.Users.AddOrUpdate(u));
            context.SaveChanges(true);
        }
}

    public virtual void InitializeDatabase(TContext context)
    {
        Check.NotNull(context, "context");

        context.Database.Delete();
        context.Database.Create(DatabaseExistenceState.DoesNotExist);
        Seed(context);
        context.SaveChanges();
    }

public override void InitializeDatabase(ABSContext context)
        {
            if (context != null)
            {
                if (context.Database.Exists())
                {
                   context.Database.Delete();
                }

                context.Database.Create();
                Seed(context);
                context.SaveChanges(true);
            }
            else
                throw new ArgumentNullException();
        }

在我的应用程序“正常”运行期间，它似乎工作得非常好（至少到目前为止）

但是，当我想使用初始值设定项重新创建数据库时会出现问题，如下所示：

public override int SaveChanges()
{
    throw new InvalidOperationException("User Id must be provided for auditing purposes.");
}

public int SaveChanges(bool suppressAudit)
{
    if (suppressAudit)
        return base.SaveChanges();
    else
        throw new InvalidOperationException("User Id must be provided for auditing purposes.");
}

public int SaveChanges(int userId)
{
    foreach(var entity in ChangeTracker.Entries().Where(p=>p.State == EntityState.Added || p.State == EntityState.Deleted || p.State == EntityState.Modified))
    {
        foreach(var auditEntry in GetAuditRecordsForChange(entity,userId))
        {
            Audit.Add(auditEntry);
        }
    }
    return base.SaveChanges();
}

public class ABS4Initializer : DropCreateDatabaseAlways<MyContext>
{        
        protected override void Seed(MyContext context)
        {
            var users = BuildUserData();            
            users.ForEach(u => context.Users.AddOrUpdate(u));
            context.SaveChanges(true);
        }
}

    public virtual void InitializeDatabase(TContext context)
    {
        Check.NotNull(context, "context");

        context.Database.Delete();
        context.Database.Create(DatabaseExistenceState.DoesNotExist);
        Seed(context);
        context.SaveChanges();
    }

public override void InitializeDatabase(ABSContext context)
        {
            if (context != null)
            {
                if (context.Database.Exists())
                {
                   context.Database.Delete();
                }

                context.Database.Create();
                Seed(context);
                context.SaveChanges(true);
            }
            else
                throw new ArgumentNullException();
        }

App.config

<entityFramework>
    <contexts>
      <context type="DAL.DAL.DemoContext, DAL">
        <databaseInitializer type="DAL.DAL.ABS4Initializer, DAL"/>
      </context>
    </contexts>
    <defaultConnectionFactory type="System.Data.Entity.Infrastructure.LocalDbConnectionFactory, EntityFramework">
      <parameters>
        <parameter value="mssqllocaldb" />
      </parameters>
    </defaultConnectionFactory>
    <providers>
      <provider invariantName="System.Data.SqlClient" type="System.Data.Entity.SqlServer.SqlProviderServices, EntityFramework.SqlServer" />
    </providers>
  </entityFramework>

---

实体框架中的DropCreateDatabaseAlways（）类具有以下虚拟方法，如果下载EF源代码，您会发现实现如下所示：

public override int SaveChanges()
{
    throw new InvalidOperationException("User Id must be provided for auditing purposes.");
}

public int SaveChanges(bool suppressAudit)
{
    if (suppressAudit)
        return base.SaveChanges();
    else
        throw new InvalidOperationException("User Id must be provided for auditing purposes.");
}

public int SaveChanges(int userId)
{
    foreach(var entity in ChangeTracker.Entries().Where(p=>p.State == EntityState.Added || p.State == EntityState.Deleted || p.State == EntityState.Modified))
    {
        foreach(var auditEntry in GetAuditRecordsForChange(entity,userId))
        {
            Audit.Add(auditEntry);
        }
    }
    return base.SaveChanges();
}

public class ABS4Initializer : DropCreateDatabaseAlways<MyContext>
{        
        protected override void Seed(MyContext context)
        {
            var users = BuildUserData();            
            users.ForEach(u => context.Users.AddOrUpdate(u));
            context.SaveChanges(true);
        }
}

    public virtual void InitializeDatabase(TContext context)
    {
        Check.NotNull(context, "context");

        context.Database.Delete();
        context.Database.Create(DatabaseExistenceState.DoesNotExist);
        Seed(context);
        context.SaveChanges();
    }

public override void InitializeDatabase(ABSContext context)
        {
            if (context != null)
            {
                if (context.Database.Exists())
                {
                   context.Database.Delete();
                }

                context.Database.Create();
                Seed(context);
                context.SaveChanges(true);
            }
            else
                throw new ArgumentNullException();
        }

您需要使用如下内容覆盖：

public override int SaveChanges()
{
    throw new InvalidOperationException("User Id must be provided for auditing purposes.");
}

public int SaveChanges(bool suppressAudit)
{
    if (suppressAudit)
        return base.SaveChanges();
    else
        throw new InvalidOperationException("User Id must be provided for auditing purposes.");
}

public int SaveChanges(int userId)
{
    foreach(var entity in ChangeTracker.Entries().Where(p=>p.State == EntityState.Added || p.State == EntityState.Deleted || p.State == EntityState.Modified))
    {
        foreach(var auditEntry in GetAuditRecordsForChange(entity,userId))
        {
            Audit.Add(auditEntry);
        }
    }
    return base.SaveChanges();
}

public class ABS4Initializer : DropCreateDatabaseAlways<MyContext>
{        
        protected override void Seed(MyContext context)
        {
            var users = BuildUserData();            
            users.ForEach(u => context.Users.AddOrUpdate(u));
            context.SaveChanges(true);
        }
}

    public virtual void InitializeDatabase(TContext context)
    {
        Check.NotNull(context, "context");

        context.Database.Delete();
        context.Database.Create(DatabaseExistenceState.DoesNotExist);
        Seed(context);
        context.SaveChanges();
    }

public override void InitializeDatabase(ABSContext context)
        {
            if (context != null)
            {
                if (context.Database.Exists())
                {
                   context.Database.Delete();
                }

                context.Database.Create();
                Seed(context);
                context.SaveChanges(true);
            }
            else
                throw new ArgumentNullException();
        }

---

您正在执行

if（suppressAudit）返回base.SaveChanges（）这是在调用断点吗？@Amit否。它正在调用基类，基类很好，并按预期跳过我的重写。（在该行上粘贴一个断点也证实了这一点）需要为DbContext发布完整的相关代码。@Amit不确定还需要从DbContext类中获得什么？除了公共DbSet属性和GetAuditRecordsForChange（）方法之外，没有其他内容了。@Amit添加了完整的dbContext代码……谢谢@Paul！由于某种原因，该方法没有显示为覆盖，但它解决了这个问题！