Registering Entity Mapping

Question

I am working in asp.net core project using EF core. I mapped my entities by overriding the OnModelCreating function in the context class. I can easily map these entities manually. Well, I would better post my codes and explain ..

This is what I did in my Context class:

protected override void OnModelCreating(ModelBuilder builder)
    {        
        base.OnModelCreating(builder);
        //builder.RegisterEntityMapping<CodeTable, CodeTableMap>();
        builder.RegisterEntityMapping<Country, CountryMap>();
        builder.RegisterEntityMapping<State, StateMap>();
        builder.RegisterEntityMapping<City, CityMap>();
        builder.RegisterEntityMapping<User, UserMap>();
        builder.RegisterEntityMapping<Prospect, ProspectMap>();
    }

Country.cs

public class Country:BaseEntity
{

    public string CountryCode { get; set; }
    public string CountryName { get; set; }
    public string Currency { get; set; }
    public string CurrencyName { get; set; }
    public string UnitOfMeasure { get; set; }
    public string TelephoneCountryCode { get; set; }
    public string CurrencySymbol { get; set; }

    public virtual ICollection<State> States { get; set; }
    public virtual ICollection<City> Cities { get; set; }
}

CountryMap.cs

public class CountryMap : QuantumEntityTypeConfiguration<Core.Domain.Country>
{
    public override void Map(EntityTypeBuilder<Core.Domain.Country> builder)
    {
        builder.ToTable("Country");
        builder.HasKey(pr => pr.CountryCode);

        builder.HasMany(m => m.Cities).WithOne(i=> i.Country).HasForeignKey(m=> m.CountryCode);
        builder.HasMany(m => m.States).WithOne(i => i.Country).HasForeignKey(m => m.CountryCode);
    }
}

But, I would like to do it dynamically as it would be hectic later on to map all the models. I could find the solution in nopCommerce's context class where they did in this way:

 protected override void OnModelCreating(DbModelBuilder modelBuilder)
    {
        //dynamically load all configuration
        //System.Type configType = typeof(LanguageMap);   //any of your configuration classes here
        //var typesToRegister = Assembly.GetAssembly(configType).GetTypes()

        var typesToRegister = Assembly.GetExecutingAssembly().GetTypes()
        .Where(type => !String.IsNullOrEmpty(type.Namespace))
        .Where(type => type.BaseType != null && type.BaseType.IsGenericType &&
            type.BaseType.GetGenericTypeDefinition() == typeof(NopEntityTypeConfiguration<>));
        foreach (var type in typesToRegister)
        {
            dynamic configurationInstance = Activator.CreateInstance(type);
            modelBuilder.Configurations.Add(configurationInstance);
        }
        //...or do it manually below. For example,
        //modelBuilder.Configurations.Add(new LanguageMap());



        base.OnModelCreating(modelBuilder);
    }

I tried to implement that and I got an error:

 protected override void OnModelCreating(ModelBuilder builder)
    {
        // TODO: Use Dynamic mapping by getting classes which uses QuantumEntityTypeConfiguration
        var typesToRegister = Assembly.GetExecutingAssembly().GetTypes()
        .Where(type => !String.IsNullOrEmpty(type.Namespace))
        .Where(type => type.BaseType != null && type.BaseType.IsGenericType &&
            type.BaseType.GetGenericTypeDefinition() == typeof(QuantumEntityTypeConfiguration<>));
        foreach (var type in typesToRegister)
        {
            dynamic configurationInstance = Activator.CreateInstance(type);                   
            builder.Configurations.Add(configurationInstance); //Error in this line specifying:ModelBuilder has no defination for Configuration.
        }}

Error

Well nopCommerce uses the DbModelBuilder from namespace: System.Data.Entity and I use ModelBuilder under namespace : Microsoft.EntityFrameworkCore.

So, if you have any solutions or recommendations. please let me know.

Answer 1

In EF Core, there is no Configurations property available on ModeBuilder as of now.

One way to work around this issue is to change your configurations to

public class CountryMap : QuantumEntityTypeConfiguration<Country>
{
    public CountryMap(ModelBuilder modelBuilder)
    {
        EntityTypeBuilder<Country> builder = modelBuilder.Entity<Country>()

        builder.ToTable("Country");
        builder.HasKey(pr => pr.CountryCode);

        builder.HasMany(m => m.Cities).WithOne(i=> i.Country).HasForeignKey(m=> m.CountryCode);
        builder.HasMany(m => m.States).WithOne(i => i.Country).HasForeignKey(m => m.CountryCode);
    }
}

And then you can add them in your DbContext's on OnModelCreating method like this:

foreach (var type in typesToRegister)
{       
    Activator.CreateInstance(type, modelBuilder);
}