Issues with complex objects

[X0RN0T]

Describe the bug
When working with Pomelo.EntityFrameworkCore.MySql Version 9 in my Blazor application i tried to work with the objects

[Table("Users")]
public class User
{
[Key]
[DatabaseGenerated(DatabaseGeneratedOption.Identity)]
public int Id { get; set; }

public Guid Guid { get; set; }

[MaxLength(256)]
[Column("firstname", TypeName = "varchar(256)")]
public string Firstname { get; set; } = string.Empty;

[MaxLength(256)]
[Column("lastname", TypeName = "varchar(256)")]
public string Lastname { get; set; } = string.Empty;

}

[Table("Restaurants")]
public class Restaurant
{
public int Id { get; set; }

[Required]
[MaxLength(200)]
public string Name { get; set; } = string.Empty;

[MaxLength(1024)]
public string? GoogleShareLink { get; set; }

public List<Ranking> Rankings { get; set; } = new();

public List<Scoring> Scorings { get; set; } = new();

[Column(TypeName = "date")]
public DateTime? ProposedDate { get; set; }

[Column(TypeName = "date")]
public DateTime? VisitedDate { get; set; }

public int CreatorId { get; set; }

public User Creator { get; set; }

}

[Table("Scorings")]
public class Scoring
{
[Key]
public int Id { get; set; }

public int Score { get; set; }

[ForeignKey(nameof(Creator))]
public int CreatorId { get; set; }

public User Creator { get; set; }

[ForeignKey(nameof(Restaurant))]
public int RestaurantId { get; set; }

public Restaurant Restaurant { get; set; }

public DateTime CreatedAt { get; set; } = DateTime.UtcNow;

}

[Table("Rankings")]
public class Ranking
{
[Key]
[DatabaseGenerated(DatabaseGeneratedOption.Identity)]
public int Id { get; set; }

[Range(0, 5)]
public double Score { get; set; }

[MaxLength(1024)]
public string ChoosenMeal { get; set; }

[MaxLength(2024)]
public string? Comment { get; set; }

[ForeignKey(nameof(Restaurant))]
public int RestaurantId { get; set; }

[JsonIgnore]
public Restaurant Restaurant { get; set; }

[ForeignKey(nameof(RankingCreator))]
public int RankingCreatorId { get; set; }

[JsonIgnore]
public User RankingCreator { get; set; }

[Column(TypeName = "date")]
public DateTime RankingDate { get; set; }

}

I tried to used my controller like

// POST: api/restaurants
[HttpPost]
public async Task<ActionResult> CreateRestaurant(Restaurant restaurant)
{
_context.Restaurants.Add(restaurant);
await _context.SaveChangesAsync();
return CreatedAtAction(nameof(GetRestaurantById), new { id = restaurant.Id }, restaurant);
}

gets Error "MySqlException: Duplicate entry '1' for key 'PRIMARY'"

Database is a Maria DB Version(10, 6, 22)

Also gets often error "StatusCode: 400, ReasonPhrase: 'Bad Request', Version: 1.1, Content: System.Net.Http.BrowserHttpContent, Headers:
{
Content-Type: application/problem+json; charset=utf-8
}"

To Reproduce
Build a PWA Blazor application and a corresponding .NET API. Design the models and the api controller, call the api

Expected behavior
Should work without error

Technical details (please complete the following information):

• Database server version: Maria DB Version(10, 6, 22)
• Operating system: Windows 11
• Pomelo.EntityFrameworkCore.MySql version: 9.0.0
• Other technical details: ASP.NET Core

Additional context
I tried to find the error in designing the models best as possible but nothing changed the problems. A workaround that works was to pass a restaurant object to the api (for not getting the bad request error) and delete it in the controller (for not getting the Duplicate entry error). But i´m sure that shouldn`t be the way

[roji]

@X0RN0T there's a good chance that this is not a MySQL/Pomelo-related issue, but a general one - if that's the case, it belongs in https://github.com/dotnet/efcore and not here.

In any case, the above is a partial bunch of snippets that makes it difficult fo maintainers to actually reproduce what's going on. When submitting issues, please always include a minimal, runnable console program (no Blazor or web code), that's very specifically doing the EF operations you're having trouble with. You can also try swapping MySQL with e.g. SQLite to see whether the issue is MySQL-specific or not.