Entity Framwork

Convention based Concurrency Management in Entity Framework Core

Who does not love convention over configuration? Whenever it makes sense I try to use it in my role as a system architect. It helps my programmers write more robust code out of the box.

Writing concurrency safe code is a corner stone in writing robust code today,  without it data quality can not be guaranteed. And when things go wrong you want to know who and when entities were updated so you can investigate what have gone wrong.

So what I did at my latest assignment was to force this onto the entities by convention using two markup interfaces ICreated and IUpdated.  (more…)

SQL CE and namespaces

We use SQL CE in our unit test project to test our EF6 queries. This works pretty well and Code first setup makes sure each test gets a fresh CE database to work with.

We ran into a problem where two EF types had the same table name but inside different schemas. CE does not support schemas and this resulted in naming conflicts when setting up database. My solution was to create a little convention.

public class BakeSchemaIntoTableNameConvention : IStoreModelConvention<EntityType>
{
    public void Apply(EntityType item, DbModel model)
    {
        var entitySet = model.StoreModel.Container.EntitySets.Single(es => es.ElementType == item);
        entitySet.Table = $"{entitySet.Schema}_{entitySet.Table}";
    }
}

It bakes the schema into the table name like dbo_MyTable. You add the convention like.

protected override void OnModelCreating(DbModelBuilder modelBuilder)
{
    modelBuilder.Conventions.Add<BakeSchemaIntoTableNameConvention>();

    modelBuilder.Configurations.AddFromAssembly(typeof (MyContext).Assembly);
}

You do not want to add this for production code so what I did was create a public event on the context. And call it from the OnModelCreating method.

protected override void OnModelCreating(DbModelBuilder modelBuilder)
{
    ModelCreating?.Invoke(this, modelBuilder);

    modelBuilder.Configurations.AddFromAssembly(typeof (MyContext).Assembly);
}

Call it from your Unittest project like.

ctx.ModelCreating += (s, e) => e.Conventions.Add<BakeSchemaIntoTableNameConvention>();

Entity framework 6 and fluent mapping

If you google for EF and fluent mapping this is the first hit you get which is not strange since its the official MSDN page about fluent mapping in EF6.

They only discuss overriding the OnModelCreating method and configure the mapping inline in that method. And this is the most common way of dealing with fluent mapping out there in the community. But there is a much better and seperated way of doing it which MSDN fail to show.

System.Data.Entity.ModelConfiguration.EntityTypeConfiguration

This little class is your salvation when working with Fluent mapping in large enterprise systems. Implement it like. (more…)