代码优先实体框架：外键 - 无效的对象名称

Question

I'm having trouble with Entity Framework and the code-first approach.

Foreign key will not link properly

Here is the error page: ( https://prnt.sc/JUWTdRVCEWq7 )

public class Organisme
{
    public int ID { get; set; }
    public string Name { get; set; } = null! ;
    public string Description { get; set; } = null! ;
    public string Image { get; set; } = null! ;

    public Soort Soort { get; set; } = null!;
}

public class Soort
{
    public int Id { get; set; }
    public string Name { get; set; } = null!;
    public Geslacht Geslacht { get; set; } = null!;

    public ICollection<Organisme> Organismes { get; set; } = null!;
}


modelBuilder.Entity<Soort>().HasMany(a => a.Organismes).WithOne(b => b.Soort);


public async Task<Organisme?> GetByIdAsync(int id)
{
    using OrganismeContext oc = new();
    return await oc.Organismes.AsNoTracking()
                   .Include(x => x.Soort)
                   .SingleOrDefaultAsync(x => x.ID == id);
}

By removing .Include(x => x.Soort) , I no longer get the error, but the value becomes null which is not what I want

Adding .HasForeignKey(c => c.Soort) gives a whole different error

InvalidOperationException: 'Soort' cannot be used as a property on entity type 'Organisme' because it is configured as a navigation.

Error pages: https://prnt.sc/1GL3-CgD1ruj and https://prnt.sc/GymTfEIhXy5x

Answer 1

You have your navigation property ( Soort ) but no foreign key column, so EF doesn't know how to link the two up, hence why you get error when trying to include. Add both a Foreign Key Property and a Navigation Property to your entity model, so for example, class Organisme { [ForeignKey(nameof(Soort)] public int SoortId {get; set;} public Soort Soort {get; set;} }

from @nbokmans in comments