LoomKit.Requests.Crud.Abstractions 10.0.1

LoomKit.Requests.Crud.Abstractions

Contracts for LoomKit.Requests.Crud: a single interface, IProjectable<TEntity, TDto>, that lets a DTO declare its own EF-Core-translatable projection expression.

Status: early stage. The public API may still change between versions — pin a commit/tag if you depend on it.

Why a separate package

IProjectable<TEntity, TDto> is implemented on your DTOs, not on your handlers. DTOs commonly live in a shared "contracts" project that is also referenced by client code (a Blazor WASM app, a mobile client, ...). That project has no business depending on LoomKit.Requests.Crud itself — the server-side CRUD handler base classes, LoomKit.Requests.Abstractions, LoomKit.Esits, and everything else that comes with it.

Referencing LoomKit.Requests.Crud.Abstractions alone gets you IProjectable with no further dependencies.

Installation

dotnet add package LoomKit.Requests.Crud.Abstractions

Usage

Implement IProjectable<TEntity, TDto> on a DTO to declare how it's built from its source entity:

using System.Linq.Expressions;
using LoomKit.Requests.Crud.Contracts;

public record ProductDto : IProjectable<Product, ProductDto>
{
    public int Id { get; init; }
    public string Name { get; init; }
    public UserDto? User { get; init; }

    // EF Core translates this into an optimized SQL SELECT.
    // Use property-initializer syntax, not a positional record constructor.
    public static Expression<Func<Product, ProductDto>> Projection =>
        e => new ProductDto
        {
            Id = e.Id,
            Name = e.Name,
            User = new UserDto
            {
                Email = e.User.Email,
                Roles = e.User.Roles.Select(r => new RoleDto
                {
                    Id = r.Id,
                    Name = r.Name
                }).ToList()
            }
        };

    // Fields included by default when the caller doesn't request specific ones.
    // Omit (or return []) to always include every field.
    public static string[] DefaultSelects => ["Id", "Name"];
}

A server-side project using LoomKit.Requests.Crud's BaseGetByIdHandler/BaseListHandler reads Projection/DefaultSelects off the DTO to build a pruned, SQL-translatable query — see that package's README for the full Selects syntax and how the projection gets pruned at request time.

License

MIT