/// <summary>
/// Lazily loads a document from the session. When the value is accessed, an exception will be thrown if the document is null.
/// </summary>
/// <typeparam name="T"></typeparam>
/// <param name="sessionOps"></param>
/// <param name="id"></param>
/// <returns></returns>
public static Lazy <Task <T> > LoadRequiredAsync <T>(this IAsyncLazySessionOperations sessionOps, string id)
{
if (id == null)
{
throw new ArgumentNullException(nameof(id), "Tried to load required entity but passed in a null ID");
}
var loadTask = sessionOps.LoadAsync <T>(id);
var wrappedLazy = new Lazy <Task <T> >(() =>
{
// When unwrapping the Lazy, return a task that does the actually loading.
var result = loadTask.Value;
return(result.ContinueWith(t =>
{
// When unwrapping the Task, return the result of the task. But if it's null, throw an execption.
if (t.Result == null)
{
throw new ArgumentException($"Tried to lazily load {id}, but it wasn't found in the database.");
}
return t.Result;
}, TaskContinuationOptions.OnlyOnRanToCompletion));
}, isThreadSafe: false);
return(wrappedLazy);
}
/// <summary>
/// Lazily loads an entity from the Raven. The result is wrapped as an optional value.
/// </summary>
/// <typeparam name="T"></typeparam>
/// <param name="lazyOps"></param>
/// <param name="id"></param>
/// <returns></returns>
public static Lazy <Task <Option <T> > > LoadOptionAsync <T>(this IAsyncLazySessionOperations lazyOps, string id)
{
var loadTask = lazyOps.LoadAsync <T>(id);
var optionTask = new Lazy <Task <Option <T> > >(() =>
{
var result = loadTask.Value;
return(result.ContinueWith(t => t.Result.SomeNotNull(), TaskContinuationOptions.OnlyOnRanToCompletion));
}, isThreadSafe: false);
return(optionTask);
}
/// <summary>
/// Lazily loads a document from the session. When the value is accessed, an exception will be thrown if the document is null.
/// </summary>
/// <typeparam name="T"></typeparam>
/// <param name="session"></param>
/// <param name="id"></param>
/// <returns></returns>
public static Lazy <Task <T> > LoadRequiredAsync <T>(this IAsyncLazySessionOperations sessionOps, string id)
{
var loadTask = sessionOps.LoadAsync <T>(id);
var wrappedLazy = new Lazy <Task <T> >(() =>
{
var result = loadTask.Value;
return(result.ContinueWith(t =>
{
if (t.Result == null)
{
throw new ArgumentException($"Tried to lazily load {id}, but it wasn't found in the database.");
}
return t.Result;
}, TaskContinuationOptions.OnlyOnRanToCompletion));
}, isThreadSafe: false);
return(wrappedLazy);
}
