private static IQueryable <TSource> OrderBy <TSource>(this IQueryable <TSource> query, string propertyName, OrderDirection direction)
{
var entity = typeof(TSource);
var propertyInfo = entity.GetProperty(propertyName, BindingFlags.GetProperty | BindingFlags.Public | BindingFlags.IgnoreCase | BindingFlags.Instance);
var arg = Expression.Parameter(entity, "x");
var property = Expression.Property(arg, propertyName);
var selector = Expression.Lambda(property, arg);
var actionName = direction.Equals(OrderDirection.Asc)
? "OrderBy"
: "OrderByDescending";
var method = typeof(Queryable).GetMethods()
.Where(m => m.Name == actionName && m.IsGenericMethodDefinition)
.Single(m =>
{
var parameters = m.GetParameters().ToList();
return(parameters.Count == 2);
});
if (propertyInfo == null)
{
return(query);
}
var genericMethod = method.MakeGenericMethod(entity, propertyInfo.PropertyType);
var newQuery = (IOrderedQueryable <TSource>)genericMethod.Invoke(genericMethod, new object[] { query, selector });
return(newQuery);
}
public IQueryable <T> GetAllAsQuery(Expression <Func <T, object> > orderby = null, OrderDirection orderDirection = OrderDirection.Asc, params Expression <Func <T, object> >[] includes)
{
IQueryable <T> query = _context.Set <T>();
if (orderby != null)
{
query = orderDirection.Equals(OrderDirection.Asc) ? query.OrderBy(orderby) : query.OrderByDescending(orderby);
}
if (includes != null)
{
foreach (var i in includes)
{
query = query.Include(i);
}
}
return(query);
}
public static IQueryable <T> OrderBy <T>(this IQueryable <T> source, string property, OrderDirection direction) where T : class
{
//STEP 1: Verify the property is valid
var searchProperty = typeof(T).GetProperty(property);
if (searchProperty == null)
{
throw new ArgumentException("property");
}
if (!searchProperty.PropertyType.IsValueType &&
!searchProperty.PropertyType.IsPrimitive &&
!searchProperty.PropertyType.Namespace.StartsWith("System") &&
!searchProperty.PropertyType.IsEnum)
{
throw new ArgumentException("property");
}
if (searchProperty.GetMethod == null ||
!searchProperty.GetMethod.IsPublic)
{
throw new ArgumentException("property");
}
//STEP 2: Create the OrderBy property selector
var parameter = Expression.Parameter(typeof(T), "o");
var selectorExpr = Expression.Lambda(
Expression.Property(parameter, property),
parameter);
//STEP 3: Update the IQueryable expression to include OrderBy
Expression queryExpr = source.Expression;
queryExpr = Expression.Call(typeof(Queryable),
direction.Equals(OrderDirection.Asc) ? "OrderBy" : "OrderByDescending",
new Type[] { source.ElementType, searchProperty.PropertyType },
queryExpr,
selectorExpr);
return(source.Provider.CreateQuery <T>(queryExpr));
}