我正在尝试使用EF4创建通用方法来查找对象的主键。
例
public string GetPrimaryKey<T>()
{
...
}
为了提供更多信息,我正在使用Tekpub StarterKit,下面是我尝试启动并运行的类
using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;
using System.Data.Objects;
using System.Data.Objects.ELinq;
using System.Data.Linq;
using Web.Infrastructure.Storage.EF4;
namespace Web.Infrastructure.Storage {
public class EFSession:ISession {
PuzzleEntities _db;//This is an ObjectContext
public EFSession() {
_db = new PuzzleEntities();
}
public void CommitChanges() {
_db.SaveChanges();
}
/// <summary>
/// Gets the table provided by the type T and returns for querying
/// </summary>
private ObjectSet<T> GetObjectSet<T>() where T:class {
return _db.CreateObjectSet<T>();
}
private T GetByPrimaryKey<T>() where T: class
{
.....
}
public void Delete<T>(System.Linq.Expressions.Expression<Func<T, bool>> expression) where T: class{
foreach (T item in All<T>().Where(expression))
{
GetObjectSet<T>().DeleteObject(item);
}
}
public void Delete<T>(T item) where T : class {
GetObjectSet<T>().DeleteObject(item);
}
public void DeleteAll<T>() where T : class {
foreach(T item in All<T>())
{
GetObjectSet<T>().DeleteObject(item);
}
}
public void Dispose() {
_db.Dispose();
}
public T Single<T>(System.Linq.Expressions.Expression<Func<T, bool>> expression) where T:class {
return GetObjectSet<T>().SingleOrDefault(expression);
}
public IQueryable<T> All<T>() where T : class {
return GetObjectSet<T>().AsQueryable();
}
public void Add<T>(T item) where T : class {
GetObjectSet<T>().AddObject(item);
}
public void Add<T>(IEnumerable<T> items) where T : class {
foreach (T item in items)
{
GetObjectSet<T>().AddObject(item);
}
}
public void Update<T>(T item) where T : class {
//nothing needed here
}
}
}
最佳答案
所以我终于能够找到如何使它起作用的方法。我希望我不会因为我未编写代码而失去到昨晚阅读的博客的链接。
public T GetByPrimaryKey<T>(int id) where T : class
{
return (T)_db.GetObjectByKey(new EntityKey(_db.DefaultContainerName + "." + this.GetEntityName<T>(), GetPrimaryKeyInfo<T>().Name, id));
}
string GetEntityName<T>()
{
string name = typeof(T).Name;
if (name.ToLower() == "person")
return "People";
else if (name.Substring(name.Length - 1, 1).ToLower() == "y")
return name.Remove(name.Length - 1, 1) + "ies";
else if (name.Substring(name.Length - 1, 1).ToLower() == "s")
return name + "es";
else
return name + "s";
}
private PropertyInfo GetPrimaryKeyInfo<T>()
{
PropertyInfo[] properties = typeof(T).GetProperties();
foreach (PropertyInfo pI in properties)
{
System.Object[] attributes = pI.GetCustomAttributes(true);
foreach (object attribute in attributes)
{
if (attribute is EdmScalarPropertyAttribute)
{
if ((attribute as EdmScalarPropertyAttribute).EntityKeyProperty == true)
return pI;
}
else if (attribute is ColumnAttribute)
{
if ((attribute as ColumnAttribute).IsPrimaryKey == true)
return pI;
}
}
}
return null;
}
我希望这可以帮助其他人。我只能说的是,它应该在方法上更加清晰。
关于c# - Entity Framework 4:如何查找主键?,我们在Stack Overflow上找到一个类似的问题:https://stackoverflow.com/questions/2958921/