More standard filters in Content Delivery API

[bjarnef]

According to documentation Content Delivery API allows to filter on a few standard fields:
https://docs.umbraco.com/umbraco-cms/reference/content-delivery-api#filter

e.g. contentType, name, createDate, updateDate

However there are other standard fields in index, which would be nice to filter, when one don't fetch from a single parent/ancestor node.

E.g. filter on ancestorIds or parentId.

This works for me to filter on multiple parent/ancestor ids, where it otherwise return all items of the filtered content types.

public class AncestorFilter : IFilterHandler
{
    private const string FilterOptionSpecifier = "ancestor:";
    private const string IndexFieldName = "ancestorIds";

    public bool CanHandle(string query)
        => query.StartsWith(FilterOptionSpecifier, StringComparison.OrdinalIgnoreCase);

    public FilterOption BuildFilterOption(string filter)
    {
        var filterValue = filter.Substring(FilterOptionSpecifier.Length);
        var negate = filterValue.StartsWith('!');
        var aliases = filterValue.TrimStart('!').Split(',', StringSplitOptions.TrimEntries | StringSplitOptions.RemoveEmptyEntries);

        return new FilterOption
        {
            FieldName = IndexFieldName,
            Values = aliases,
            Operator = negate
                ? FilterOperation.IsNot
                : FilterOperation.Is
        };
    }
}

Perhaps other may be relevant like level.