Learn how to create a base controller in ASP.NET core here - https://danielk.tech

BaseController.cs

using System;
using System.Collections.Generic;
using System.Linq;
using System.Threading.Tasks;
using Microsoft.AspNetCore.Mvc;
using Microsoft.EntityFrameworkCore;

namespace BaseController.Controllers
{
    [ApiController]
    public class BaseController<TEntity> : ControllerBase where TEntity : BaseModel
    {
        protected readonly BaseControllerDBContext _context;
        protected DbSet<TEntity> _dbSet { get; set; }
        public BaseController(BaseControllerDBContext context) 
        { 
            _context = context;
            _dbSet = _context.Set<TEntity>();
        }

        [HttpGet]
        public virtual async Task<IEnumerable<TEntity>> GetAllAsync()
        {
            return await _dbSet.ToListAsync();
        }

        [HttpGet("{id}")]
        public virtual async Task<TEntity> GetAsync(Guid id)
        {           
            return await _dbSet.Where(e => e.Id == id).FirstOrDefaultAsync();
        }

        [HttpDelete("{id}")]
        public virtual async Task DeleteAsync(Guid id)
        {           
            var entity = await _dbSet.Where(e => e.Id == id).FirstOrDefaultAsync();
            _dbSet.Remove(entity);
            await _context.SaveChangesAsync();
        }

        [HttpPost]
        public virtual async Task<TEntity> CreateAsync(TEntity entity)
        {           
            await _dbSet.AddAsync(entity);
            await _context.SaveChangesAsync();
            return entity;
        }

        [HttpPost]
        public virtual async Task<TEntity> UpdateAsync(TEntity entity)
        {           
            _dbSet.Update(entity);
            await _context.SaveChangesAsync();
            return entity;
        }
    }
}