I'm trying to perform a LINQ query on a DataTable object and bizarrely I am finding that performing such queries on DataTables is not straightforward. For example: var results = from myRow in myDataTable where results.Field("RowNo") == 1 select results; This is not allowed. How do I get something like this working? I'm amazed that LINQ queries are not allowed on DataTables! You ca
我试图对DataTable对象执行LINQ查询，奇怪的是我发现在DataTable上执行这样的查询并不简单。 例如： var results = from myRow in myDataTable where results.Field("RowNo") == 1 select results; 这是不允许的。 我如何得到这样的工作？ 我很惊讶LINQ查询不允许在DataTable上！ 由于DataRowCollection未实现IEnumerable<T> ，因此无法对DataTable的Rows集合进行查询。 您需要为DataTable使用AsEnumerable()扩展
We have successfully called our callback function in SDL Audio with the following setup. struct { SDL_AudioSpec spec; /* SDL Audio Spec Structure */ Uint8 *sound; /* Pointer to wave data */ Uint32 soundlen; /* Length of wave data */ int soundpos; /* Current play position */ } wave; void fillerup(void *unused, Uint8 *stream, int len) { Uint8 *waveptr; int waveleft=0; printf("in fillerup:%d",wave
我们已经使用以下设置成功地在SDL Audio中调用了我们的回调函数。 struct { SDL_AudioSpec spec; /* SDL Audio Spec Structure */ Uint8 *sound; /* Pointer to wave data */ Uint32 soundlen; /* Length of wave data */ int soundpos; /* Current play position */ } wave; void fillerup(void *unused, Uint8 *stream, int len) { Uint8 *waveptr; int waveleft=0; printf("in fillerup:%d",wave.soundlen); waveptr = wave.
I'm implementing Charikar's fast search on a locality sensitive hash and I'm looking for a fast method of permuting bits (the kind of thing that can be done in one operation in MMIX) in C#. The requirements are: Always less than 64 bits, so representation can be a long integer Randomly generate a permutation (this can be slow as it's only done once). I'll probably use a
我正在实现Charikar对局部敏感散列的快速搜索，并且正在寻找一种在C＃中快速排列位（在MMIX中可以在一个操作中完成的事情）的方法。 要求是： 总是小于64位，因此表示可以是一个长整数 随机生成一个排列（这可能很慢，因为它只能执行一次）。 我可能会使用Knuth shuffle。 使用生成的排列很多次，所以这需要很快 我知道Knuth详细介绍了这一点，但我想知道是否有任何.NET / C＃特定的解决方案。 编辑：我使用.NET版
I have an entity class Timecard , I get this entity from this method: public Timecard GetTimeCardForPerson(long timecardId) { return timecardContext.First(item => item.TimeCardId = timeCardId); } timecardContext is of type TimecardContext: DbContext . I later make a change to the Timecard entity, the Timecard entity has a property: public virtual ICollection<TimecardRow> TimeCa
我有一个实体类Timecard ，我从这个方法得到这个实体： public Timecard GetTimeCardForPerson(long timecardId) { return timecardContext.First(item => item.TimeCardId = timeCardId); } TimecardContext: DbContext的类型是TimecardContext: DbContext 。 我后来对Timecard实体进行了更改， Timecard实体具有一个属性： public virtual ICollection<TimecardRow> TimeCardRows { get; set; } 它在Timec
I have an Entity Territory public partial class Territory { public Territory() { this.Employees = new HashSet<Employee>(); } public string TerritoryID { get; set; } public string TerritoryDescription { get; set; } public int RegionID { get; set; } public virtual Region Region { get; set; } public virtual ICollection<Employee> Employees { get;
我有一个实体地区 public partial class Territory { public Territory() { this.Employees = new HashSet<Employee>(); } public string TerritoryID { get; set; } public string TerritoryDescription { get; set; } public int RegionID { get; set; } public virtual Region Region { get; set; } public virtual ICollection<Employee> Employees { get; set; } }
I have been exploring different methods of editing/updating a record within Entity Framework 5 in an ASP.NET MVC3 environment, but so far none of them tick all of the boxes I need. I'll explain why. I have found three methods to which I'll mention the pros and cons: Method 1 - Load original record, update each property var original = db.Users.Find(updatedUser.UserId); if (original
在ASP.NET MVC3环境中，我一直在探索在Entity Framework 5中编辑/更新记录的不同方法，但到目前为止，他们都没有打勾我需要的所有框。 我会解释为什么。 我已经找到了三种方法，我会提及利弊： 方法1 - 加载原始记录，更新每个属性 var original = db.Users.Find(updatedUser.UserId); if (original != null) { original.BusinessEntityId = updatedUser.BusinessEntityId; original.Email = updatedUser.Email;
I'm looking for the fastest way of inserting into Entity Framework. I'm asking this because of the scenario where you have an active TransactionScope and the insertion is huge (4000+). It can potentially last more than 10 minutes (default timeout of transactions), and this will lead to an incomplete transaction. To your remark in the comments to your question: "...SavingChange
我正在寻找插入Entity Framework的最快方式。 我问这是因为你有一个活跃的TransactionScope的场景，插入是巨大的（4000+）。 它可能会持续超过10分钟（事务的默认超时），并且这将导致不完整的事务。 要对你的问题发表评论： “... SavingChanges（ 对于每个记录 ）...” 这是你能做的最糟糕的事！ 为每个记录调用SaveChanges()会极大地降低批量插入的速度。 我会做几个简单的测试，这很可能会提高性能： 在ALL记录后
I have a problem with Entity Framework in Asp.net. I want to get the Id value whenever I add an object to database. How can I do this? It is pretty easy. If you are using DB generated Ids (like IDENTITY in MS SQL) you just need to add entity to ObjectSet and SaveChanges on related ObjectContext . Id will be automatically filled for you: using (var context = new MyContext()) { context.MyE
我在Asp.net中遇到了实体框架问题。 无论何时将对象添加到数据库，我都想获取Id值。 我怎样才能做到这一点？ 这很容易。 如果您使用数据库生成的ID（如MS SQL中的IDENTITY ），则只需将实体添加到ObjectSet和SaveChanges相关的ObjectContext 。 Id会自动为您填写Id ： using (var context = new MyContext()) { context.MyEntities.AddObject(myNewObject); context.SaveChanges(); int id = myNewObject.Id; // Ye
Is there a way to get all the changes made to a object in the Entity Framework before it saves all changes. The reason for this is that i want to create a log table in our clients database: so... Is there a way to get the current database values(old) and the new values(current) before changes are saved? If not, how can i achieve this in a generic way, so all my View Models can inherit from
是否有方法在保存所有更改之前获取对Entity Framework中的对象所做的所有更改。 原因是我想在我们的客户数据库中创建一个日志表： 所以... 有没有办法在更改保存之前获取当前数据库值（旧）和新值（当前）？ 如果没有，我怎样才能以通用的方式实现这一点，所以我所有的视图模型都可以继承它（我正在使用MVVM + M结构） 您可以使用ObjectContext的ObjectStateManager和GetObjectStateEntry来获取对象的ObjectStateEntry
This code fails to actually save any changes: // // POST: /SomeType/Edit/5 [AcceptVerbs(HttpVerbs.Post)] public ActionResult Edit(Guid id, SomeType Model) { db.AttachTo(Model.GetType().Name, Model); db.ApplyPropertyChanges(Model.EntityKey.EntitySetName, Model); db.SaveChanges(); return RedirectToAction("Index"); } ASP.NET MVC creates the object Model as a Department type Entity
此代码未能实际保存任何更改： // // POST: /SomeType/Edit/5 [AcceptVerbs(HttpVerbs.Post)] public ActionResult Edit(Guid id, SomeType Model) { db.AttachTo(Model.GetType().Name, Model); db.ApplyPropertyChanges(Model.EntityKey.EntitySetName, Model); db.SaveChanges(); return RedirectToAction("Index"); } ASP.NET MVC使用EntityState值为Detached将对象Model创建为部门类型EntityObject。