NHibernate SchemaExport: How to generate a meaningful unique key name?

Question

When I use SchemaExport with SQL Server 2005, it generate unique key name like: UQ_Employees_03317E3D

Hom can I generate a name like: UQ_Employees_Name? Even in SQL Server!

Answer 1

I think that there is a couple of ways to do what you are trying to to.

The first one is to specify the name in the mapping file. I know it works for foreign keys, though I haven't tried with unique keys.

<property name="KeyId" column="KeyId" type="Int" unique="true" unique-key="MyKeyName"/>

Within NHibernate you can change the Naming Strategy by creating a class that implements NHibernate.Cfg.INamingStrategy and adding that class when you configure nhibernate.

ISessionFactory sf = new Configuration()  
     .SetNamingStrategy(new YourNamingStrategy())  
     .Configure()  
     .SchemaExport(true, false);

The is also an ImprovedNamingStrategy that is built in to nhibernate. Can't remember what it outputs off hand but worth a try

ISessionFactory sf = new Configuration()
    .SetNamingStrategy(ImprovedNamingStrategy.Instance)
    .Configure()
    .SchemaExport(true, false);

EDIT
There are a couple of other possibilities I have found the first one involves the property tag. there is a column tag that has a number of attributes that may be of use.

<property name=KeyID>
  <column name="KeyId" unique-key="MyKeyName"/>
</property>

the other one is a bit more involved You can either add something like this

<database-object >
   <create>
      create table MyTable(
      Id UNIQUEIDENTIFIER not null,
      Name NVARCHAR(10) not null,
      RowVersion INT not null,

      primary key (Id)
      )

ALTER TABLE dbo.MyTable ADD  
  CONSTRAINT IX_Table_1 UNIQUE NONCLUSTERED(Name) 
  WITH( STATISTICS_NORECOMPUTE = OFF, IGNORE_DUP_KEY = OFF, 
  ALLOW_ROW_LOCKS = ON, ALLOW_PAGE_LOCKS = ON) ON [PRIMARY]
    </create>
    <drop></drop>
</database-object>

Or create a class that implements NHibernate.Mapping.IAuxiliaryDatabaseObject which will create the DDL statements.
Have a look in the NHiberate manual on NHForge and scroll down to

5.6. Auxiliary Database Objects

This explains what you need to do.