问题描述
我在寻找的 DataContext.GetTable＆LT的等效; TEntity＆gt;在实体框架。我已经找到了 ObjectContext.CreateQuery＆LT; T＆GT; 方法，但它是从 DataContext.GetTable＆LT不同，TEntity＆GT; 自它需要一个查询字符串工作。
I'm looking for an equivalent of the DataContext.GetTable<TEntity> in Entity Framework.I've found the ObjectContext.CreateQuery<T> method but it is different from DataContext.GetTable<TEntity> since it needs a querystring to work.
有没有一种方法可以使用该实体类型的表一个IQueryable对象，而无需指定查询字符串？
Is there a way to get an IQueryable object for a table using the entity type without specifying the querystring?
*编辑：增加了code段*
这是一个与LINQ2SQL工作存储库类，我实现的一个片段。我不能使用 ObjectContext的。[表名] ，因为它不会是通用的了。
* Added code snippet*
This is a snippet of a Repository class I've implemented that works with linq2sql. I can't use ObjectContext.[TableName] because it wouldn't be generic anymore.
public class BaseRepository<TClass> : IDisposable
where TClass : class
{
protected BaseRepository(DataContext database)
{
_database = database;
}
...
public IQueryable<TClass> GetAllEntities()
{
IQueryable<TClass> entities = _database.GetTable<TClass>();
return entities;
}
public IQueryable<TClass> GetEntities(Expression<Func<TClass, bool>> condition)
{
IQueryable<TClass> table = _database.GetTable<TClass>();
return table.Where(condition);
}
*编辑：增加了我的解决方案（到目前为止..）*
这是我使用的是什么：
* Added my solution (so far..)*
This is what I'm using:
public IQueryable<TClass> GetEntities(Expression<Func<TClass, bool>> condition)
{
IQueryable<TClass> table = _database.CreateQuery<TClass>(typeof(TClass).Name);
return table.Where(condition);
}
这个工作，只要类名是相同的表名。这将成为一个问题，对我来说，当我开始使用不同的对象同一个表。
This works as long as the class name is the same of the table name. This will became a problem for me when I'll start using different objects for the same table.
我希望我已经清楚，在此先感谢，
马可：）
I hope I've been clear, thanks in advance,
Marco :)
推荐答案
其实，EF设计者本身使用的createQuery 与硬codeD字符串的静态引用。如果你深入到设计文件，你会看到这样的内容：
Actually, the EF designer itself uses CreateQuery with hard-coded strings for the static references. If you dig into the designer file you'll see something like this:
public global::System.Data.Objects.ObjectQuery<Customers> Customers
{
get
{
if ((this._Customers == null))
{
this._Customers = base.CreateQuery<Customers>("[Customers]");
}
return this._Customers;
}
}
private global::System.Data.Objects.ObjectQuery<Customers> _Customers;
在技术上有没有完美的解决方案，因为你可以使用不同的实体集相同的实体类型。但是你可以给它的老学院尝试：
Technically there's no perfect solution because you can use the same entity type for different entity sets. But you can give it the old college try:
public IQueryable<TEntity> GetEntities<TEntity>()
{
Type t = typeof(TEntity);
var edmAttr = (EdmEntityTypeAttribute)Attribute.GetCustomAttribute(t,
typeof(EdmEntityTypeAttribute), false);
if (edmAttr == null) // Fall back to the naive way
{
return context.CreateQuery<TEntity>(t.Name);
}
var ec = context.MetadataWorkspace.GetEntityContainer(
context.DefaultContainerName, DataSpace.CSpace);
var entityType = context.MetadataWorkspace.GetType(edmAttr.Name,
edmAttr.NamespaceName, DataSpace.CSpace);
var es = ec.BaseEntitySets.First(es => es.ElementType == entityType);
return context.CreateQuery<TEntity>(es.Name);
}
这篇关于难道实体框架有DataContext.GetTable＆LT的等效; TEntity＆GT;从LINQ2SQL（ObjectContext.CreateQuery＆LT; T＆GT;？）的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持！