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.
Is there a way to get an IQueryable object for a table using the entity type without specifying the querystring?
*EDIT: 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);
}
*EDIT: 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);
}
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.
I hope I've been clear, thanks in advance,
Marco :)
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;
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);
}
public IQueryable GetTable<T>(T entity) where T : class
{
return context.CreateObjectSet<T>();
}
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