Microsoft.EntityFrameworkCore.DbUpdateException: An error occurred while saving the entity changes. See the inner exception for details

Question

I'm Learning web APIs, so I'm trying to build a simple API connected to a SQL server. I got this error when I add new movie data:

Microsoft.EntityFrameworkCore.DbUpdateException: An error occurred while saving the entity changes. See the inner exception for details. ---> Microsoft.Data.SqlClient.SqlException (0x80131904): The INSERT statement conflicted with the FOREIGN KEY constraint "FK_Movies_SuperHeroes_HeroId". The conflict occurred in database "SupersDb", table "dbo.SuperHeroes", column 'HeroId'.

I have two models:

Superhero Model:

namespace SuperHeroesApi.Models
{
    public class SuperHero
    {
        [Key]
        [DatabaseGenerated(DatabaseGeneratedOption.Identity)]
        public int HeroId { get; set; }

        [Required]
        [MaxLength(100)]
        public string Name { get; set; } 

        [MaxLength(100)]
        public string FirstName { get; set; } 

        [MaxLength(100)]
        public string LastName { get; set; }

        [MaxLength(100)]
        public string City { get; set; } 
    }
}

Movie Model:

namespace SuperHeroesApi.Models
{
    public class Movie
    {
        [Key]
        [DatabaseGenerated(DatabaseGeneratedOption.Identity)]
        public int MovieId { get; set; }

        [Required]
        [MaxLength(100)]
        public string Title { get; set; }

        public int Year { get; set; }

        public double Rate { get; set; }

        public byte [] Poster { get; set; }

        [ForeignKey("SuperHero")]
        public int HeroId { get; set; }
       
        //public string  SuuperHeroName { get; set; }

        public virtual SuperHero SuperHero { get; set; }
    }
}

dto :

namespace SuperHeroesApi.Otds
{
    public class MoviesDtos
    {
        public string Title { get; set; }

        public int Year { get; set; }

        public double Rate { get; set; }

        public IFormFile Poster { get; set; }

        [ForeignKey("SuperHero")]
        public int HeroId { get; set; }
    }
}

MoviesController:

using SuperHeroesApi.Otds;

namespace SuperHeroesApi.Controllers
{
    [Route("api/[controller]")]
    [ApiController]
    public class MoviesController : ControllerBase
    {
        private readonly AppDbContext _dbContext;

        private new List<string> _allowedExtention = new List<string> { "jbg", "png" };
        private long _maxAllowedPosterSize = 5242880;

        public MoviesController(AppDbContext dbContext)
        {
            _dbContext = dbContext;
        }

        [HttpGet]
        public async Task<IActionResult>GetAllAsync()
        {
            var movie = await _dbContext.Movies.ToListAsync();

            return Ok(movie);

        }

        [HttpPost]
        public async Task <IActionResult> CreateAsync([FromForm] MoviesDtos dto)
        {
            if (_allowedExtention.Contains(Path.GetExtension(dto.Poster.FileName).ToLower()))
                return BadRequest();

            using var dataStream = new MemoryStream();
            await dto.Poster.CopyToAsync(dataStream);

            var movie = new Movie
            {
                Title = dto.Title,
                Year = dto.Year,
                Rate = dto.Rate,
                Poster = dataStream.ToArray(),
            };

            await _dbContext.AddAsync(movie);
            _dbContext.SaveChanges();

            return Ok(movie);
        }
    }
}

you are referencing superhero in movies, when you then create a new movie, you don't set the heroid. — gsharp
– gsharp, Commented Feb 3, 2022 at 18:40
@gsharp hi, do you mean in the movie model or the dot? can you explain more please — ha33
– ha33, Commented Feb 3, 2022 at 18:42

Qudus · Accepted Answer · 2022-02-03 18:43:29Z

7

You probably already have existing rows before you made changes to your schema. Now that you're creating a new foreignkey HeroId in movie which cannot be null and an integer for that matter which means it will be a zero by default. It becomes a problem for the existing rows because they will try to reference a Hero entity with Id of 0 which doesn't exist. So, the obvious solution is to make the foreign key nullable and redo the migrations

[ForeignKey("SuperHero")] 
public int? HeroId { get; set; }

answered Feb 3, 2022 at 18:43

Qudus

1,5392 gold badges14 silver badges24 bronze badges

Sign up to request clarification or add additional context in comments.

2 Comments

Qudus Over a year ago

I'm curious. You had this answer marked as accepted, then you removed it later. did it not solve your problem?

ha33 Over a year ago

your answer guided me to a better way to solve my problem and to implement my app better than the way I have planned, so thank you

ipodtouch0218 · Accepted Answer · 2024-08-29 19:07:59Z

0

Make sure you are not giving Id by yourself, it will automatically generate it.

If your class look like this

public class Canditate:Entity,IHasCreationTime
{
    [Required]
    public String Name { get;set; } 

    public String Position { get; set; }
    public DateTime CreationTime { get; set ; }

    public Canditate()
    {
        CreationTime = DateTime.Now;    
    }
}

edited Aug 29, 2024 at 19:07

ipodtouch0218

3,4259 gold badges17 silver badges31 bronze badges

answered Jul 12, 2023 at 11:45

Mohmd Taimoor

11 bronze badge

Collectives™ on Stack Overflow

Microsoft.EntityFrameworkCore.DbUpdateException: An error occurred while saving the entity changes. See the inner exception for details

2 Answers 2

2 Comments

Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

2 Answers 2

2 Comments

Comments

Your Answer

Sign up or log in

Post as a guest

Related