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Edwin Romero
Asked: 2022-03-31 07:25:48 +0800 CST 2022-03-31 07:25:48 +0800 CST

Retrieving related data at various levels with Entity Framework Core 3.1 or higher

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Although there is information on the net that gives you a guide to answer this question, it is normally in English and is distributed in several documents, so I have decided to publish it so that others who are looking for information in Spanish have an idea.

I assume that we know how to relate the entities via the entity framework and what we are going to deal with here is how to retrieve all the information.

problem I have a class structure like this

enter image description here

As I anticipated, we have the entity configured in the ContextBase in such a way that they are related, but I have the problem that I do not know how to retrieve several levels, that is, retrieving master - detail is a piece of cake (there are only 2 levels) but in this case there are 5 levels. How can i do this then?

When reading documentation it said that it was not possible, but it is possible and we will see it later. This Solution has been tested with EF Core 3.1 and 5.0.

asp.net-core

1 Answers

  1. Best Answer

    We must have the related tables more or less in the base context, you would see something like this

      protected override void OnModelCreating(ModelBuilder modelb)
  {

       //Relación suceso->datosuceso 
       modelb.Entity<datosuceso>().HasOne(p => p.suceso)
       .WithMany(c => c.datosucesos)
       .HasForeignKey(p => p.IdSuceso);

       //Relación datosuceso->datocaracteristicosuceso 
       modelb.Entity<datocaracteristicosuceso>().HasOne(p => p.datosuceso)
       .WithMany(c => c.datocaracteristicosucesos)
       .HasForeignKey(p => p.IdDatoSuceso);

       //Datosucesoadif -> datosuceso
       modelb.Entity<datosucesoadif>().HasOne(f => f.datosuceso)
            .WithMany(t => t.datosucesoadifs).HasForeignKey(t => t.IdDatoSuceso);

       //FicheroSuceso -> datosuceso
       modelb.Entity<ficherosuceso>().HasOne(f => f.datosuceso)
            .WithMany(t => t.Ficherosucesos).HasForeignKey(p => p.IdDatoSuceso);

       //datosucesocaracteristicoadif -> datosuceso
       modelb.Entity<datocaracteristicosucesoadif>().HasOne(t => t.datosuceso)
            .WithMany(f => f.datocaracteristicosucesoadifs).HasForeignKey(p => p.IdDatoSuceso);

       //Datomattodante -> datosucesoadif
       modelb.Entity<datomatrodantesuceso>().HasOne(t => t.Datosucesoadif)
            .WithMany(f => f.Datomatrodantesucesos).HasForeignKey(p => p.IdDatosSucesoAdif);

       //Consecuenciasuseso -> datosucesoadif
       modelb.Entity<consecuenciasuceso>().HasOne(t => t.Datosucesoadif)
            .WithMany(f => f.Consecuenciasucesos).HasForeignKey(p => p.IdDatosSucesoAdif);

  }

    I do not dwell much on this, it is not the objective, but then how do I recover all the information, then the code with comments to explain it.

    /// Here is the first level, the relation that includes EVENT AND SUCCESS DATA (you can see the image above) /// here everything is easy master detail with include

                    var rList = await iData.suceso.Include(a => a.datosucesos)

    ///third level here we are going to add Dataecessadif, eventfile, etc. we are going to start /// with datsucesoadif because it has a fourth level so we put a "ThenInclude(b => ///b.datosucesoadifs)" adding this 3rd level and then another "ThenInclude(c => c.Datomatrodanteucesos )" /// which adds a fourth level

                         .ThenInclude(b => b.datosucesoadifs).ThenInclude(c => c.Datomatrodantesucesos)

    ///As we have to add another table to the fourth level, it is done by placing another ThenInclude /// but this one has something special, as you can see it cannot be done like the first one because otherwise ///Entity would think it is a fifth level and it is not that's why we tell it that it is still /// the fourth level of this form d.AdifDataEvent.EventConsequence

                         .ThenInclude(d => d.Datosucesoadif.Consecuenciasucesos)

    ///Add the others of the third level easily as you can see here

                         .Include(a => a.datosucesos).ThenInclude(e => e.datocaracteristicosucesos)
                     .Include(a => a.datosucesos).ThenInclude(f => f.datocaracteristicosucesoadifs)
                     .Include(a => a.datosucesos).ThenInclude(g => g.Ficherosucesos)

    ///look here we have an extra table so we can make multilevel calls

                         .Include(a => a.datosucesos).ThenInclude(h => h.datosucesorebaseseñals).ToListAsync();

    in the end something like this

        namespace Infrastructure.Repository.Services
{
     public class ServiceSuceso : ServiceGeneric<suceso>, ISuceso
     {
          private readonly DbContextOptionsBuilder<ContextBase> _OptionsBuilder;

          public ServiceSuceso()
          {
               _OptionsBuilder = new DbContextOptionsBuilder<ContextBase>();
          }

          public async Task<List<suceso>> GetAllSucesos()
          {
               try
               {
                    using var iData = new ContextBase(_OptionsBuilder.Options);

                    var rList = await iData.suceso.Include(a => a.datosucesos)
                         .ThenInclude(b => b.datosucesoadifs).ThenInclude(c => c.Datomatrodantesucesos)
                         .ThenInclude(d => d.Datosucesoadif.Consecuenciasucesos)
                         .Include(a => a.datosucesos).ThenInclude(e => e.datocaracteristicosucesos)
                         .Include(a => a.datosucesos).ThenInclude(f => f.datocaracteristicosucesoadifs)
                         .Include(a => a.datosucesos).ThenInclude(g => g.Ficherosucesos)
                         .Include(a => a.datosucesos).ThenInclude(h => h.datosucesorebaseseñals).ToListAsync();

                    return rList;
               }
               catch (Exception e)
               {
                    return null;
               }
          }
     }
}

    And I hope that it will be of some use to you as it has served me, greetings

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