Extract individual DataSourceRequest.Filters in Kendo.Mvc on server side, and rearrange the filter logic

filterRearrange.cs

using Kendo.Mvc;

///
/// I needed to modify my incoming kendoGrid dataSourceRequest filters to append additional columns that is not bounded on the kendoGrid,
/// to do that I needed to extract all the [FilterDescriptor] for the columns,
/// this is to correct the arrangement of the [CompositeFilterDescriptor] as I needed it
/// 
/// for some reason when adding it via JS on the client side, logically I got:
/// {
/// 	|    // Group A   |     |              // Group B                 |
///	(ColumnAACondition) AND (ColumnBACondition) AND (ColumnBBCondition)
/// }
///
/// and I wanted it to be like the following instead:
/// 
/// {
/// 	|    // Group A   |     |              // Group B                  |
/// 	(ColumnAACondition) AND {(ColumnBACondition) OR (ColumnBBCondition)}
/// }
/// 
/// the encompasing curly braces for BA & BB and the curly brace on line 16 & 19, is a [CompositeFilterDescriptor],
/// it has the property of LogicalOperator to determine if the descriptors within it operate as an OR or AND logic gate.
/// 
/// The following method extracts the nested [CompositeFilterDescriptor] & [FilterDescriptor] into a single List of filters
/// 

public List<FilterDescriptor> filterSeparator(IEnumerable<IFilterDescriptor> filters)
{
	List<FilterDescriptor> _descriptors = new List<FilterDescriptor>();
	
	if (filters.Any())
	{
		foreach (var filter in filters)
		{
			var descriptor = filter as FilterDescriptor;
			if (descriptor != null)
			{
				_descriptors.Add(descriptor);
			}
			else if (filter is CompositeFilterDescriptor)
			{
				var _r = filterSeparator(((CompositeFilterDescriptor)filter).FilterDescriptors);
				if (_r.Any())
				{
					_descriptors.AddRange(_r);
				}
			}
		}
	}
	
	return _descriptors;
}

/// I then used another method to sort via FilterDescriptor.Member property to get the column name for said filter. 
/// I then group them as I wanted them into a [CompositeFilterDescriptor] for each group
/// And then I placed all those [CompositeFilterDescriptor] into a final [CompositeFilterDescriptor] like the following
/// 
/// {
/// 	(columnAACondition) AND {(columnBAcondition) OR (columnBBcondition)} AND {( {(columnCAcondition) OR (columnCBcondition)} AND columnCCcondition)}
/// }
/// 
/// And finally it's simple to replace the [DataSourceRequest] filters as following
public IActionResult DummyAction([DataSourceRequest]DataSourceRequest dsr)
{
	var newFilters = filterSeparator(dsr.Filters); // output result: List<FilterDescriptor>
	var rearrangedFilters = filterRearranger(newFilters); // output result: CompositeFilterDescriptor
	
	dsr.Filters.Clear();
	dsr.Filters.Add(rearrangedFilters);
	
	// ...
	var table = callDataSource();
	var data = table.ToDataSourceResultAsync(dsr);
	// ...
	
	return Json(data);
}