编译查询:
public static class Machines
{
public static readonly Func<OperationalDataContext, short, Machine>
QueryMachineById =
CompiledQuery.Compile((OperationalDataContext db, short machineID) =>
db.Machines.Where(m => m.MachineID == machineID).SingleOrDefault()
);
public static Machine GetMachineById(IUnitOfWork unitOfWork, short id)
{
Machine machine;
// Old code (working)
//var machineRepository = unitOfWork.GetRepository<Machine>();
//machine = machineRepository.Find(m => m.MachineID == id).SingleOrDefault();
// New code (making problems)
machine = QueryMachineById(unitOfWork.DataContext, id);
return machine;
}
看起来编译的查询返回来自另一个数据上下文的结果
[TestMethod]
public void GetMachinesTest()
{
using (var unitOfWork = IoC.Get<IUnitOfWork>())
{
// Compile Query
var machine = Machines.GetMachineById(unitOfWork, 3);
// In this unit of work everything works…
// Machine from repository (table) is equal to Machine from compile query.
}
using (var unitOfWork = IoC.Get<IUnitOfWork>())
{
var machineRepository = unitOfWork.GetRepository<Machine>();
// Get From Repository
var machineFromRepository = machineRepository.Find(m => m.MachineID == 2).SingleOrDefault();
// Get From COmpiled Query
var machine = Machines.GetMachineById(unitOfWork, 2);
VerifyMachine(machineFromRepository, 2, "Machine 2", "222222", ...);
VerifyMachine(machine, 2, "Machine 2", "222222", ...);
Assert.AreSame(machineFromRepository, machine); // FAIL
}
}
如果我运行其他(复杂)单元测试,我会得到预期的:
已尝试附加或添加非新的实体,可能已从另一个DataContext加载.
另一个重要信息是此测试是在TransactionScope下进行的(但即使没有事务处理,问题也会出现.)!
我正在使用使用XML映射到数据库的POCO.
更新:
看起来下一个链接描述了类似的问题(这个bug是解决了吗?):
http://social.msdn.microsoft.com/Forums/en-US/linqprojectgeneral/thread/9bcffc2d-794e-4c4a-9e3e-cdc89dad0e38
最佳答案 您可以尝试将上下文的ObjectTrackingEnabled设置为false.这在同样的情况下帮助了我,但我后来在更新和插入记录时打开它.
DBDataContext.ObjectTrackingEnabled = false; // Read Only