C#•4w ago

Generic converter bounding in EF Core

Is there an way to "easily" define converters for all properties which uses an generic type? Currently, I have something like this:

protected override void ConfigureConventions(ModelConfigurationBuilder configurationBuilder)
{
    configurationBuilder.Properties<EntityId<User>>().HaveConversion<EntityIdValueConverter<User>>();
    configurationBuilder.Properties<EntityId<Tenant>>().HaveConversion<EntityIdValueConverter<Tenant>>();
}

protected override void ConfigureConventions(ModelConfigurationBuilder configurationBuilder)
{
    configurationBuilder.Properties<EntityId<User>>().HaveConversion<EntityIdValueConverter<User>>();
    configurationBuilder.Properties<EntityId<Tenant>>().HaveConversion<EntityIdValueConverter<Tenant>>();
}

and an ugly static method that gets all properties from entities, map eachs one and applies the converter using reflection and activator.

1 Reply

cypherpotato•4w ago

currently, i'm using this:

static void ApplyGenericConverter(ModelBuilder modelBuilder, Type commonType, Type converterGenericType, int? maxLength = null)
{
    foreach (var entityType in modelBuilder.Model.GetEntityTypes())
    {
        var properties = entityType.ClrType.GetProperties()
            .Where(p => p.PropertyType.IsAssignableTo(commonType));

        foreach (var property in properties)
        {
            var converterType = converterGenericType.MakeGenericType(property.PropertyType.GenericTypeArguments[0]);

            var converter = Activator.CreateInstance(converterType);
            if (converter is null)
            {
                throw new Exception("Error creating the dynamic converter object: " + entityType.ClrType.ToString() + " Property: " + property.ToString());
            }

            var builder = modelBuilder.Entity(entityType.Name).Property(property.Name)
                .HasConversion((ValueConverter)converter);

            if (maxLength is int ml) builder = builder.HasMaxLength(ml);
        }
    }
}

protected override void OnModelCreating(ModelBuilder modelBuilder)
{
    ApplyGenericConverter(modelBuilder, typeof(IEntityId), typeof(EntityIdValueConverter<>), maxLength: 26 + 1 + 3);
    ApplyGenericConverter(modelBuilder, typeof(IJsonBox), typeof(JsonBoxValueConverter<>));
}

static void ApplyGenericConverter(ModelBuilder modelBuilder, Type commonType, Type converterGenericType, int? maxLength = null)
{
    foreach (var entityType in modelBuilder.Model.GetEntityTypes())
    {
        var properties = entityType.ClrType.GetProperties()
            .Where(p => p.PropertyType.IsAssignableTo(commonType));

        foreach (var property in properties)
        {
            var converterType = converterGenericType.MakeGenericType(property.PropertyType.GenericTypeArguments[0]);

            var converter = Activator.CreateInstance(converterType);
            if (converter is null)
            {
                throw new Exception("Error creating the dynamic converter object: " + entityType.ClrType.ToString() + " Property: " + property.ToString());
            }

            var builder = modelBuilder.Entity(entityType.Name).Property(property.Name)
                .HasConversion((ValueConverter)converter);

            if (maxLength is int ml) builder = builder.HasMaxLength(ml);
        }
    }
}

protected override void OnModelCreating(ModelBuilder modelBuilder)
{
    ApplyGenericConverter(modelBuilder, typeof(IEntityId), typeof(EntityIdValueConverter<>), maxLength: 26 + 1 + 3);
    ApplyGenericConverter(modelBuilder, typeof(IJsonBox), typeof(JsonBoxValueConverter<>));
}

but that doens't seems correct. each entity has an strong typed ID EntityId<TEntity>, and I want to map all of them for all entities. so, what's the better way to create an converter for all EntityId<> without using reflection and activator?

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Generic converter bounding in EF Core