CODEWITHSUNDEEP
c#entity-frameworkasp.net-web-apiasp.net-coreentity-framework-core
Aaron
Aaron

Reputation: 1061

How to load related entities with the Entity Framework Core

I am exploring with Entity Framework Core and started off by using the code first approach while reading through this guide https://docs.efproject.net/en/latest/platforms/aspnetcore/new-db.html with the exception of different models.

In EF6 it had lazy loading and I was able to pull the related entities really easily but it is no working in EF Core. I was wondering how to get this working or if there is a work around to get it working.

Here is an example of what Two of my models look like:

public class Team
{
    public string Id { get; set; }
    public string Name { get; set; }
    public string Icon { get; set; }
    public string Mascot { get; set; }
    public string Conference { get; set; }
    public int NationalRank { get; set; }

    public List<Game> Games { get; set; }
}

public class Game
{
    public string Id { get; set; }
    public string Opponent { get; set; }
    public string OpponentLogo { get; set; }
    public string GameDate { get; set; }
    public string GameTime { get; set; }
    public string TvNetwork { get; set; }
    public string TeamId { get; set; }

    public Team Team { get; set; }
}

I am wanting to get all of the Games for a Team but as of right now it is null.

I decided to make a Web Api project so I have a controller called TeamsController and when I make a GET request to the controller I want to get a list of Teams with the Games property populated with the related games.

Here is what I have tried:

[HttpGet]
public async Task<List<Team>> Get()
{
    return await _context.Teams.Include(t => t.Games).ToListAsync();
}

This is the JSON result:

[
  {
    "id": "007b4f09-d4da-4040-be3a-8e45fc0a572b",
    "name": "New Mexico",
    "icon": "lobos.jpg",
    "mascot": "New Mexico Lobos",
    "conference": "MW - Mountain",
    "nationalRank": null,
    "games": [
      {
        "id": "1198e6b1-e8ab-48ab-a63f-e86421126361",
        "opponent": "vs Air Force*",
        "opponentLogo": "falcons.jpg",
        "gameDate": "Sat, Oct 15",
        "gameTime": "TBD ",
        "tvNetwork": null,
        "teamId": "007b4f09-d4da-4040-be3a-8e45fc0a572b"
      }
    ]
  }
]

When I do this:

[HttpGet]
public async Task<List<Team>> Get()
{
    return await _context.Teams.ToListAsync();
}

I get all of the teams but the Games property is null.

I was hoping it would return all the teams in the database along with all of the games for each team. How can I get this working?

Upvotes: 4

Views: 644

Answers (1)

hokkos
hokkos

Reputation: 499

Lazy loading is currently not implemented in entity framework core as indicated here, I suggest you to look at AutoMapper to project your desired results in POCO. Because what you want will exactly cause the n+1 problem.

Upvotes: 2

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