C＃-Dll插件和实体框架

Question

I am using a PluginManager which searches for dll Files and add them (and her functions) to my current application.

I also use Entity Framework to create a database and tables from objects, but I have to declare the objects for the database in the DatabaseContext class.

How can I save some objects from a plugin in this database?

I tried this:

    protected override void OnModelCreating(DbModelBuilder modelBuilder)
    {
        foreach( PluginDto plugin in BackendContext.Current.PluginManager._plugins) {
            foreach(Type obj in plugin.plugin.getPluginDatabaseObjects())
            {
                Type typ = typeof(EntityTypeConfiguration<>).MakeGenericType(obj);

                List<MethodInfo> l = modelBuilder.GetType().GetMethods().ToList<MethodInfo>();

                MethodInfo m_Entitiy = modelBuilder.GetType().GetMethod("Entity").MakeGenericMethod(new Type[] { obj });
                var configObj = m_Entitiy.Invoke(modelBuilder, null);

                MethodInfo m_ToTable = configObj.GetType().GetMethod("ToTable", new Type[] { typeof(String) });
                m_ToTable.Invoke(configObj, new object [] { obj.Name });
            }
        }
    }

But get this exception:

An unhandled exception of type 'System.InvalidOperationException' occurred in EntityFramework.dll

Additional information: The model backing the 'DatabaseContext' context has changed since the database was created. Consider using Code First Migrations to update the database ( http://go.microsoft.com/fwlink/?LinkId=238269 ).

Answer 1

EF can support adding dynamic DBSets using this following example .

The idea is that, instead of manually creating your DbSets on your Db Context, you overload the OnModelCreating method, which allows to build types on the fly.

Bear in mind that ths sample takes a custom attribute PersistentAttribute , used to annotate classes in order for this code to find out which classes fits into model generation.