Select Expression Support

[enisn]

Summary

This feature aims to generate an expression for .Select() Linq method.

Declaration

See usage example for better understanding:

• Entity

public class Book
{
  public string Name { get; set; }

  public int TotalPage { get; set; }

  public DateTime CreateDate { get; set; }

  public virtual ICollection<BookOrder> BookOrders { get; set; }
}

• FilterDto (As always but inherits SelectorFilterBase)

public class BookFilterDto : SelectorFilterBase<BookDto>
{
  [ToLowerContainsComparison]
  public string Name { get; set; }

  public Range<int> TotalPage { get; set; }

  public Range<DateTime> CreateDate { get; set; }
}

• Output dto:

public class BookDto
{
  [From("Name")]
  public string Title { get; set; }

  public int TotalPage { get; set; }

  public DateTime CreateDate { get; set; }

  [Count("BookOrders")]
  public int SellCount { get; set; }

  [Sum("BookOrders.Price")]
  public float TotalSoldPrice { get; set; }
}

---

Usage

As default, SelectorFilterBase should override ApplyFilter() method, so calling ApplyFilter method will work.

[HttpGet]
public IActionResult GetBooks([FromQuery] BookFilterDto filter)
{
    var query = db.Books.ApplyFilter(filter);  // IQueryable<BookDto>
    return Ok(query.ToList());
}

• Or alternative usage:

As default, SelectorFilterBase should override ApplyFilter() method, so calling ApplyFilter method will work.

[HttpGet]
public IActionResult GetBooks([FromQuery] BookFilterDto filter)
{
    var query = db.Books.ApplySelector(filter)  // IQueryable<BookDto>
                            .Where(x => x.TotalSoldPrice > 299.95); // If db provider supports.

    return Ok(query.ToList());
}

Structure

• FilterBase
  • OrderableFilterBase
    • PaginationFilterBase
      • SelectorFilterBase

TODO List

• Extension methods for last user usage
• SelectorFilterBase and SelectorPaginationFilterBase implementation.
• Attributes
  • Sum
  • Count
  • Min
  • Max
  • Average

[enisn]

This might be useful:
https://stackoverflow.com/questions/12701737/expression-to-create-an-instance-with-object-initializer/12705338#12705338

[enisn]

Dynamic Select is not compatible with Open API 3.0 standards. This is the main purpose of AutoFilterer. Only static select support can be provided.

• Also, this is a 'Filtering' library, it doesn't aim projection by the way