MireaBackend/Application/Cqrs/Faculty/Commands/CreateFaculty/CreateFacultyCommandHandler.cs

using MediatR;
using Microsoft.EntityFrameworkCore;
using Mirea.Api.DataAccess.Application.Common.Exceptions;
using Mirea.Api.DataAccess.Application.Interfaces.DbContexts.Schedule;
using System.Threading;
using System.Threading.Tasks;

namespace Mirea.Api.DataAccess.Application.Cqrs.Faculty.Commands.CreateFaculty;

public class CreateFacultyCommandHandler(IFacultyDbContext dbContext) : IRequestHandler<CreateFacultyCommand, int>
{
    public async Task<int> Handle(CreateFacultyCommand request, CancellationToken cancellationToken)
    {
        var entity = await dbContext.Faculties.FirstOrDefaultAsync(f => f.Name == request.Name, cancellationToken: cancellationToken);

        if (entity != null)
            throw new RecordExistException(typeof(Domain.Schedule.Faculty), nameof(Domain.Schedule.Faculty.Name), entity.Id);

        var faculty = new Domain.Schedule.Faculty()
        {
            Name = request.Name,
            CampusId = request.CampusId
        };

        var result = await dbContext.Faculties.AddAsync(faculty, cancellationToken);
        await dbContext.SaveChangesAsync(cancellationToken);

        return result.Entity.Id;
    }
}