关于c＃：如何刷新DbContext

How to Refresh DbContext

我想刷新我的DbContext的所有实体而不重新创建它，我尝试了以下操作，但没有一个有意义：

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var context = ((IObjectContextAdapter)myDbContext).ObjectContext;

var refreshableObjects = (from entry in context.ObjectStateManager.GetObjectStateEntries(
EntityState.Added
| EntityState.Deleted
| EntityState.Modified
| EntityState.Unchanged)
where entry.EntityKey != null
select entry.Entity);

context.Refresh(RefreshMode.StoreWins, refreshableObjects);
//.......................................................................
foreach (var entry in this.Orm.ChangeTracker.Entries())
{
entry.State = EntityState.Unchanged;
}
this.Orm.ChangeTracker.DetectChanges();

而唯一的刷新我的DbContext：

1 2	foreach (var i in this.Orm.ChangeTracker.Entries()) i.Reload();

但这太慢了。您能帮我选择正确的方法吗？

相关讨论

在某些情况下，如果某个集合已由第三方应用程序更新，则刷新该集合的对象时可能不会重新加载该集合。

我遇到的情况是，我的对象A与对象B具有一对多的关系。

应用程序1加载A.ListB为空的对象A。
应用程序2填充A.ListB集合。
应用程序1重新加载对象A。

使用上述解决方案，A.ListB保持为空。我必须显式重新加载集合A.ListB。

这是重新加载所有集合的一种通用方法：

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var context = ((IObjectContextAdapter)this).ObjectContext;

// detach all added entities
ChangeTracker.Entries().Where(e => e.State == EntityState.Added).ToList().ForEach(e => e.State = EntityState.Detached);

// select entities
var refreshableObjects = ChangeTracker.Entries().Select(e => e.Entity).ToList();

// refresh each refreshable object
foreach (var @object in refreshableObjects)
{
// refresh each collection of the object
context.ObjectStateManager.GetRelationshipManager(@object).GetAllRelatedEnds().Where( r => r.IsLoaded).ToList().ForEach( c => c.Load() );

// refresh the object
context.Refresh(RefreshMode.StoreWins, @object);
}

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using System.Data.Entity.Core.Objects;
using System.Data.Entity.Infrastructure;
using System.Linq;

namespace System.Data.Entity
{
public static class DbContextExtensions
{
/// <summary>
/// Refresh non-detached entities
/// </summary>
/// <param name="dbContext">context of the entities</param>
/// <param name="refreshMode">store or client wins</param>
/// <param name="entityType">when specified only entities of that type are refreshed. when null all non-detached entities are modified</param>
/// <returns></returns>
public static DbContext RefreshEntites(this DbContext dbContext, RefreshMode refreshMode, Type entityType)
{
//https://christianarg.wordpress.com/2013/06/13/entityframework-refreshall-loaded-entities-from-database/
var objectContext = ((IObjectContextAdapter)dbContext).ObjectContext;
var refreshableObjects = objectContext.ObjectStateManager
.GetObjectStateEntries(EntityState.Added | EntityState.Deleted | EntityState.Modified | EntityState.Unchanged)
.Where(x => entityType == null || x.Entity.GetType() == entityType)
.Where(entry => entry.EntityKey != null)
.Select(e => e.Entity)
.ToArray();

objectContext.Refresh(RefreshMode.StoreWins, refreshableObjects);

return dbContext;
}

public static DbContext RefreshAllEntites(this DbContext dbContext, RefreshMode refreshMode)
{
return RefreshEntites(dbContext: dbContext, refreshMode: refreshMode, entityType: null); //null entityType is a wild card
}

public static DbContext RefreshEntites<TEntity>(this DbContext dbContext, RefreshMode refreshMode)
{
return RefreshEntites(dbContext: dbContext, refreshMode: refreshMode, entityType: typeof(TEntity));
}
}
}

在数据库中插入后，我有一个触发器，并且正在事务中进行操作，因此我需要在相同的上下文中获取由触发器生成的新值。这为我工作：

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using (var ctx = new context())
{
ctx.Connection.Open();
ctx.Transaction = ctx.Connection.BeginTransaction();

ctx.Entities.InsertOnSubmit(itemDB);
ctx.SubmitChanges();
ctx.Refresh(RefreshMode.OverwriteCurrentValues, itemDB);

Model newModel = itemDB.ToModel();

ctx.Transaction.Commit();
return newModel;
}
catch (Exception ex)
{
ctx.Transaction.Rollback();
}