EF6 Linq Query。仅包含返回子表的第一个条目

Question

I would like to retrieve a list of Encounters for a Given Pokemon, as a Pokemon can be encountered in many places, so I've been trying many variants of

var currentPokemon = _context.Pokemon
                                     .Where(mon => mon.Id == id)
                                     .Include(mon => mon.Encounters)
                                     .FirstOrDefault();

With the result being a Pokemon object with all of the relevant data, but only the FIRST encounter being retrieved and put into a collection resulting in this:

Looking at the database, there are about 20 encounters for caterpie, and I'd like access to all of them, but only ever just get the one.

What the Pokemon class looks like (irrelevant fields omitted):

[Table("pokemon")]
public partial class Pokemon {
    public Pokemon()
    {
        Encounters = new HashSet<Encounters>();
    }
    [Column("id")]
    public long Id { get; set; }
    [Required]
    [Column("identifier", TypeName = "VARCHAR(79)")]
    public string Identifier { get; set; }
    .
    .
    .

    [InverseProperty("Pokemon")]
    public virtual ICollection<Encounters> Encounters { get; set; }
 }

What Encounters looks like:

public partial class Encounters {
    .
    .
    .
    [ForeignKey("PokemonId")]
    [InverseProperty("Encounters")]
    public virtual Pokemon Pokemon { get; set; }
}

Db data :

What am I misunderstanding here?

Answer 1

I think its because you are calling .FirstOrDefault() , which is only getting the first item. Can you omit that and add .ToList() ? Also, var currentPokemon doesn't seem like a good variable name. You said you want a list of Encounters, right? How about var pokemonEncounters ?

Answer 2

I think that the problem is the way that you set the relationship using ForeignKey and InverseProperty.

Try to rewrite to something like:

[Table("Pokemon")]
public class Pokemon
{
    public int Id { get; set; }
    public string Name { get; set; }

    [InverseProperty("Pokemon")]
    public ICollection<Encounter> Encounters { get; set; }

}

[Table("Enconters")]
public class Encounter
{
    public int Id { get; set; }

    public int PokemonId { get; set; }

    [ForeignKey("PokemonId")]
    public Pokemon Pokemon { get; set; }

}

Answer 3

My apologies, I've been looking to the wrong places for my answer. After stepping through this in a debugger, I can see that my Pokemon query does indeed return the desired result: A pokemon with many encounters attached. My problem seems to be elsewhere (specifically: the JSONified object I'm seeing come through to my web front-end truncates the encounters array to contain only the first result).

I'll post a new question with the correct problem and link to it from here when it's figured out.