unique-key, but not primary key

naa · **Joined:** Thu Feb 05, 2009 7:31 pm **Posts:** 9

I've got an easy question, i hope i will be luckier than latest time i asked a generical quesiton in this forum (although i know that my problem was not easy to be understood)

In order to avoid boring you with my particular classes, i'm exposing my current situation with a similar example

Let's assume the following class:

Code:

Class Student
{
         public int StudentId;
         public string FirstName;
         public string MiddleName;
         public string SecondName;
}

I'm assuming that in case StudentId were primary key, mapping should seem like this:

Code:

<class name="Student" table="STUDENTS">
      <id name="StudentId">
          <column name="StudentID"/>
          <generator class="native"/>
      </id>
      <property name="FirstName"/>
      <property name="MiddleName"/>
      <property name="SecondName"/>
</class>

But, what if i wanted to make FirstName/MiddleName/SecondName an unique index?

I've tried with following:

Code:

<class name="Student" table="STUDENTS">
      <id name="StudentId">
          <column name="StudentID"/>
          <generator class="native"/>
      </id>
      <property name="FirstName" unique-key="NAME_MUST_BE_UNIQUE"/>
      <property name="MiddleName" unique-key="NAME_MUST_BE_UNIQUE"/>
      <property name="SecondName" unique-key="NAME_MUST_BE_UNIQUE"/>
</class>

I'm using _session.SaveOrUpdate, but i still seeing unique constraints violated. After digging into forum, i've started to think that unique-key it's just intende to crate tables, but it's unuseful for already created tables processing

Does NHibernate provide any way to (let say) check FirstName MiddleName and SecondName and insert in case there were not violating unique constraing and update when they were?

I'm working on SQLExpress, but it's intende to move to Oracle in near future

Thanks for any helpful answer you can provide me.

wolli · **Posted:** Fri Feb 13, 2009 1:27 am

Quote:

i've started to think that unique-key it's just intende to crate tables, but it's unuseful for already created tables processing

You're right. It's only used during schema export.

Quote:

Does NHibernate provide any way to (let say) check FirstName MiddleName and SecondName and insert in case there were not violating unique constraing and update when they were?

Not really. You either have to go and use try/catch or do the validation yourself before you insert the object. YOu can have a look at NHibernate.Validator project if they provide a more general approach.