如何解决如何使用反射调用DomainService.Load方法？
| 我正在尝试构建一个实用程序方法，该方法通常将使用反射加载实体集合。这个想法是，使用该实用程序的程序员可以指定任何类型的实体，并且该方法将发现正确的EntityQuery并使用他们所请求的内容加载上下文。因此，我已经从用户那里收集了Entity类型和Where子句，现在我试图弄清楚如何调用该方法。这是我所拥有的：public void Handle(LoadEntityQuery loadQuery,Action<LoadEntityQueryResult> reply)
{
foreach (var entry in loadQuery.Entities)
{
Type entityType = entry.Key;
Type _contextType = EmployeeJobsContext.Instance.GetType();
MethodInfo _methodInfo = (from x in _contextType.GetMethods()
where x.ReturnType.BaseType == typeof(EntityQuery)
from y in x.ReturnType.GetGenericArguments()
where y == entityType
select x).FirstOrDefault();
if (_methodInfo != null)
{
var query = _methodInfo.Invoke(EmployeeJobsContext.Instance,null);
var _loadMethods = from x in _contextType.GetMethods()
where x.Name == \"Load\" &&
x.GetParameters().Length == 3
select x;
MethodInfo _loadMethod = null;
if (_loadMethods != null)
{
foreach (MethodInfo item in _loadMethods)
{
ParameterInfo[] _paramInfo = item.GetParameters();
if (_paramInfo[0].ParameterType.BaseType == typeof(EntityQuery) &&
_paramInfo[1].ParameterType.IsGenericType &&
_paramInfo[1].ParameterType.GetGenericArguments().Length == 1 &&
_paramInfo[1].ParameterType.GetGenericArguments()[0].BaseType == typeof(LoadOperation) &&
_paramInfo[2].ParameterType == typeof(object))
{
_loadMethod = item;
break;
}
}
}
MethodInfo _loadOpMethod = this.GetType().GetMethod(\"LoadOperationResult\");
Delegate d = Delegate.CreateDelegate(typeof(LoadOpDel),_loadOpMethod);
if (_loadMethod != null)
{
object [] _params = new object[3];
_params[0] = query;
_params[1] = d;
_params[2] = null;
_loadMethod = _loadMethod.MakeGenericMethod(entityType);
_loadMethod.Invoke(_context,_params);
}
}
}
}
public delegate void LoadOpDel(LoadOperation loadOp);
public void LoadOperationResult (LoadOperation loadOp)
{
if (loadOp.HasError == true)
{
//reply(new LoadEntityQueryResult { Error = loadOp.Error.Message });
loadOp.MarkErrorAsHandled();
}
}
解决方法
好吧，在不了解您正在使用的类的任何其他信息的情况下，我无法真正测试我的解决方案，但是当我从for循环中删除委托创建时，我就可以使其工作。我将您的目标方法更改为静态：
public static void LoadOperationResult(LoadOperation loadOp)
Action<LoadOperation>
LoadOpDel
/// <summary>
/// The Action callback for the LoadEntityQuery handler. This callback is used to respond to the
/// LoadEntityQuery when all Load calls are complete. See the Handle method
/// </summary>
private Action<LoadEntityQueryResult> _reply = null;
/// <summary>
/// Accumulator used to determine when the last entity has been loaded
/// </summary>
private int EntityCount { get; set; }
/// <summary>
/// Collective error container for Errors from the LoadOperation. This is value is returned via
/// the _reply callback to the calling code.
/// </summary>
private List<Exception> Errors = null;
public void Handle(LoadEntityQuery loadQuery,Action<LoadEntityQueryResult> reply)
{
_reply = reply;
Errors = new List<Exception>();
EntityCount = loadQuery.Entities.Count();
MethodInfo _loadOpMethod = this.GetType().GetMethod(\"Load\",BindingFlags.NonPublic | BindingFlags.Instance);
int _entityCount = loadQuery.Entities.Count();
foreach (var entry in loadQuery.Entities)
{
Type entityType = entry.Key;
Type _contextType = EmployeeJobsContext.Instance.GetType();
MethodInfo _methodInfo = (from x in _contextType.GetMethods()
where x.ReturnType.BaseType == typeof(EntityQuery)
from y in x.ReturnType.GetGenericArguments()
where y == entityType
select x).FirstOrDefault();
if (_methodInfo != null)
{
var query = _methodInfo.Invoke(EmployeeJobsContext.Instance,null);
MethodInfo _typedLoadOpMethod = _loadOpMethod.MakeGenericMethod(new Type[] { entityType });
_typedLoadOpMethod.Invoke(this,new[] { query,entry.Value});
}
}
}
private void Load<T>(EntityQuery<T> query,Expression<Func<T,bool>> where) where T: Entity
{
if (where != null)
query = query.Where(where);
EmployeeJobsContext.Instance.Load(query,(loadOp) =>
{
EntityCount--;
if (loadOp.HasError)
{
Errors.Add(loadOp.Error);
loadOp.MarkErrorAsHandled();
}
if (EntityCount == 0)
_reply(new LoadEntityQueryResult { ErrorList = Errors });
},null);
}
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