entity 如何为dbcontext运行时动态附加上一个dbset

[gispk47]

类似这样

public class DefaultDBContext :DBContext{
    public DbSet<User> User {get;set;}
    ..........
}

需要动态增加类似这个user的entity我现在只知道它的type的string；想用dbcontext读取这个未知实体的数据，有什么思路吗

[save4me]

参考 Creating DbSet Properties Dynamically

DbSet<MyEntity> set = context.Set<MyEntity>();

或

DbSet set = context.Set( typeof( MyEntity ) );

或者利用反射，通过实现DbContext的OnModelCreating方法，参考 Dynamically Adding DbSet Properties in DbContext for Entity Framework Code First

引用

However, for a project with even a fair bit of domain complexity, defining DbSet properties for all entities would not be possible and we need a way to dynamically read our Entity Types and add them dynamically in the DbContext. This can be achieved by implementing OnModelCreating method of the DbContext. The Entity Types can be read from either the executing assembly Assembly.GetExecutingAssembly() or by loading more than one assemblies which can be placed in a configuration file (as shown below in the example). For details about setting up the custom configuration section with your assemblies see my last post The following code will add all Class Types to the DbContext for all the assemblies added in the configuration file, notice we are actually calling modelBuilder.Entity<T>() method through reflection.

public class MyAppContext : DbContext
    {
        protected override void OnModelCreating(DbModelBuilder modelBuilder)
        {
            CustomAssemblySection configSection = (CustomAssemblySection)System.Configuration.ConfigurationManager.GetSection("CustomAssemblySection");
 

            foreach (CustomAssembly customAssembly in configSection.Assemblies)
            {
                Assembly assembly = Assembly.Load(customAssembly.Name);
                foreach (Type type in assembly.ExportedTypes)
                {
                    if (type.IsClass)
                    {
                        MethodInfo method = modelBuilder.GetType().GetMethod("Entity");
                        method = method.MakeGenericMethod(new Type[] { type });
                        method.Invoke(modelBuilder, null);
                    }
                }
            }
            base.OnModelCreating(modelBuilder);
        }
    }