AutoFilterer aim is keeping models strong-typed and removing complicated algorithms while filtering. With AutoFilterer, you define only filter object with rules and do not write any LINQ Expression, AutoFilterer does it for you.


Create a filter object that inherits from FilterBase. Create a property for each field you want to filter.

  • Property names should match entity property names. If not use [CompareTo] attribute.

  • ValueTypes should be nullable in case the value is not sent. Otherwise, even the value isn't sent, the filter will be applied with the default value of ValueType.

public class BookFilter : FilterBase // 👈 Inherit from FilterBase
    public string Title { get; set; }
    public int? Year { get; set; } // 👈 Value Types have to be nullable
    // ...
    // Only written properties can be filterable

(If property names doesn't match or can't match, you can use [CompareTo] attribute to define entity property name. Check out Property name mapping for more info).


FilterBase implements IFilter interface that has ApplyFilter method. That means, the class you inherit from FilterBase is able to generate filters on collections.

public IActionResult GetBooks([FromQuery]BookFilter filter)
    var query = filter.ApplyFilterTo(db.Books);

    return Ok(query.ToList());

ApplyFilter() Extension method

You can also use ApplyFilter extension method for IQueryable<T> types.

public IActionResult GetBooks([FromQuery]BookFilter filter)
    return Ok(db.Books.ApplyFilter(filter).ToList());

Those properties can be used in the following ways in querystring.

/books?title=Middlemarch /books?title=Nostromo&year=1904

Further reading

In this document