我可以将我的Database.SetInitializer调用放入具有基本字符串而不是静态构造函数的上下文构造函数中吗？

Question

I am using Entity Framework to store some entities generated at run time using Codedom. I am actually also creating my contexts dynamically using Codedom too. Before I started dynamically generating contexts I was using a hardcoded context. The start of this hardcoded context class (up to the constructors) looked like this:

public class EntityModelContext : DbContext, IEntityRegistry
{
    static EntityModelContext()
    {
        Database.SetInitializer(new DropCreateDatabaseIfModelChanges<EntityModelContext>());
    }

    public EntityModelContext()
        : base("EntityModelContext")
    {
        EntityToRegisterDictionary = new ConcurrentDictionary<string, Assembly>();
    }

This was all good. However, I tried generating this using Codedom and discovered that static isn't a thing with Codedom. Even if I could generate a static constructor, I was getting an error which basically said that there are two constructors and I don't know which one to use. So then I merged these two constructors in my Codedom generated context class, and it now looks like this (note it's called TreeContext because I am creating a context for every entity I make and I'm making a tree entity with it in my tests):

TreeContext() : 
        base("TreeContext")
{
    Database.SetInitializer(new DropCreateDatabaseIfModelChanges<TreeContext>());
    EntityToRegisterDictionary = new ConcurrentDictionary<string, Assembly>();
}

I just tried running a test which generates a tree entity class and an instance of this tree entity, as well as the corresponding tree context class and an instance of this tree context. I tried inserting this tree entity instance into the tree context instance and it seems to have worked in SQL Server. Therefore I guess the constructor works. However, I wanted to make sure with anyone else who understands better how Database.SetInitializer works. I thought it had to be called before the base connection string is called, but it seems to work. Anyway I have only tested inserting an entity instance. I haven't tried changing the model or anything more complex.

Answer 1

You can use SetInitializer where you want. Usually is in the static constructor of the context because is static.

System.Data.Entity.Database.SetInitializer(...);

Usually is called when you first access context functions (is not enough to create the context). Usually at first read or at first SaveChanges.

You can also generate a static constructor with CodeDom with CodeTypeConstructor instead of CodeContructor.