Question

I am using linq to sql for my mvc 3 project. There are several ways to generate domain modal class files.

1. sqlmetal
2. Object Relational Designer
3. hand code

I always hand code those model class files. because files generated by sqlmetal or designer are messy. whats your opinion? whats the best way to do it.

EDIT:

I am using MVC 3, not 2. Maybe I am wrong, but this is how I validate. I gonna end up writing all those class files anyway, so whats the point to use tools to generate them???

public class User
{ 
    [Required]
    public string Password { get; set; } 
    [Required, Compare("Password")] 
    public string ComparePassword { get; set; } 
}

Answer 1

We have hundreds of tables across multiple databases (one server). We do table first development, drag the tables onto different DBML designer files each in different folders representing different namespaces within each project. The designer files are marked not to compile, and we use a custom built T4 template that generates our code by reading from whatever DBML files are in the project. This lets us have full control of the code that’s generated, so we can do things like implement an interface (IAuditable is one example where we have CreatedBy, CreatedDate, ModifiedBy, ModifiedDate). We can also put System.ComponentModel.DataAnnotations on our Linqed objects this way too without resorting to Buddy Classes. We have a second T4 template that’s in charge of refreshing the DBML from the database, so we can ensure that tables have the 3 part prefix (db.schema.tbl) and so we don’t have to delete and re-add to the designer. The XML just gets changed based on reading the db schema and updating the DBML. We also generate a repository/manager object for each POCO that have a few common query operations like GetByID(), and also handle commits and the audit logging. These managers get extended with all the custom queries you’d need to write against each table, and they own the DataContext. This design is sometimes known as the “Mommy-may-I?” approach, where the object Linqed to the table has to ask its manager to do everything for it.

I’ve found this to be a very versatile and slick way of doing L2S, and it’s made our back-end development a breeze so that we can put our focus on the user experience. The only downside is that if we do associations across namespaces, you have to manually add those to the partial class yourself, because otherwise you’d have to add that foreign table to another DBML in order to draw the association. This is actually not such a bad thing as causes us to really think about the specificity of our namespaces and cut down extra ones. Using T4 this way is a great way to develop DRY (don’t repeat yourself). The table definition is the only place you need to change the structure and it all propogates. Validation goes in one place, the POCO. Queries go in one place, the manager. If you want to do something similar, here’s a good place to start.