static QueryFilterAttribute()
{
ToFutureMethod =
ReflectHelper.GetMethodDefinition(() => LinqExtensionMethods.ToFuture <object>(null))
.GetGenericMethodDefinition();
ToFutureValueMethod =
ReflectHelper.GetMethodDefinition(() => LinqExtensionMethods.ToFutureValue <object, object>(null, null))
.GetGenericMethodDefinition();
GetCountExpressionMethod = ReflectHelper.GetMethodDefinition <QueryFilterAttribute>(o => o.GetCountExpression <object>())
.GetGenericMethodDefinition();
}
/// <summary>
/// Gets the result of a getter-expression from the query, but lazily so
/// that the data-source will not be contacted until the value is retrieved.
/// </summary>
/// <returns>The lazy value.</returns>
/// <param name="query">The query.</param>
/// <typeparam name="T">The type of object queried.</typeparam>
public Lazy <T> GetLazyValue <T>(IQueryable <T> query)
{
if (query == null)
{
throw new ArgumentNullException(nameof(query));
}
if (!(query.Provider is NhQueryProvider))
{
throw new ArgumentException($"The query provider must be an instance of {typeof(NhQueryProvider).FullName}.", nameof(query));
}
var futureValue = LinqExtensionMethods.ToFutureValue(query);
return(new Lazy <T>(() => futureValue.Value));
}