DbFirst/DbFirst.Application/Catalogs/Commands/CreateCatalogHandler.cs

using AutoMapper;
using DbFirst.Domain.Entities;
using DbFirst.Domain.Repositories;
using MediatR;

namespace DbFirst.Application.Catalogs.Commands;

public class CreateCatalogHandler : IRequestHandler<CreateCatalogCommand, CatalogReadDto?>
{
    private readonly ICatalogRepository _repository;
    private readonly IMapper _mapper;

    public CreateCatalogHandler(ICatalogRepository repository, IMapper mapper)
    {
        _repository = repository;
        _mapper = mapper;
    }

    public async Task<CatalogReadDto?> Handle(CreateCatalogCommand request, CancellationToken cancellationToken)
    {
        var existing = await _repository.GetByTitleAsync(request.Dto.CatTitle, cancellationToken);
        if (existing != null)
        {
            return null;
        }

        var entity = _mapper.Map<VwmyCatalog>(request.Dto);
        entity.AddedWho = "system";
        entity.AddedWhen = DateTime.UtcNow;
        entity.ChangedWho = "system";
        entity.ChangedWhen = DateTime.UtcNow;

        var created = await _repository.InsertAsync(entity, cancellationToken);
        return _mapper.Map<CatalogReadDto>(created);
    }
}