private static Expression <Func <T, bool> > GetExpression <T>(
MappingCollection <T> mappings,
FilterGroup filterGroup
) where T : class
{
var predicate = PredicateBuilder.New <T>(filterGroup.Operator == FilterOperator.And);
var filterApplied = false;
foreach (var filter in filterGroup.Filters.Where(f => !string.IsNullOrWhiteSpace(f.Value)))
{
var mapping = mappings.GetMapping(filter.Field);
var expression = mapping.GetFilterLambda(filter.Value, filter.Action);
if (expression == null)
{
continue;
}
filterApplied = true;
if (filterGroup.Operator == FilterOperator.And)
{
predicate = predicate.And(expression);
}
else
{
predicate = predicate.Or(expression);
}
}
// if an or filter doesnt actually do any filtering, we return true.
// this allows us to ignore empty predicates
if (!filterApplied && filterGroup.Operator == FilterOperator.Or)
{
predicate = PredicateBuilder.New <T>(true);
}
if (filterGroup.FilterGroups != null)
{
foreach (var group in filterGroup.FilterGroups)
{
if (filterGroup.Operator == FilterOperator.And)
{
predicate = predicate.And(GetExpression <T>(mappings, group));
}
else
{
predicate = predicate.Or(GetExpression <T>(mappings, group));
}
}
}
return(predicate);
}
private IQueryable <TEntityType> ApplySort <TEntityType>(
IQueryable <TEntityType> query,
FilterSet filter,
MappingCollection <TEntityType> mappings
) where TEntityType : class
{
if (!string.IsNullOrWhiteSpace(filter.SortBy))
{
var mapping = mappings.GetMapping(filter.SortBy);
return(mapping.ApplySort(query, filter.SortDir ?? mappings.DefaultSort.SortOrder));
}
var defaultSort = mappings.DefaultSort;
return(defaultSort.Mapping.ApplySort(query, filter.SortDir ?? mappings.DefaultSort.SortOrder));
}
private IQueryable <TEntityType> ApplySort <TEntityType>(
IQueryable <TEntityType> query,
FilterSet filter,
MappingCollection <TEntityType> mappings
) where TEntityType : class
{
var isDescending = filter.SortDir == "desc";
var isAscending = filter.SortDir == "asc";
bool?selectedSort = isDescending ? true : (isAscending ? false : (bool?)null);
if (!string.IsNullOrWhiteSpace(filter.SortBy))
{
var mapping = mappings.GetMapping(filter.SortBy);
return(mapping.ApplySort(query, selectedSort ?? mappings.DefaultSort.Descending));
}
var defaultSort = mappings.DefaultSort;
return(defaultSort.Mapping.ApplySort(query, selectedSort ?? mappings.DefaultSort.Descending));
}