What is the Primary Key of this ORM Entity

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• #1 by Ben Nadel on 12/21/09 - 11:21 AM

  

  What does it return if the primary key is composed of more than one column? Is that even possible (I can't remember what I read about relationships).

• #2 by Dan Vega on 12/21/09 - 11:29 AM

  

  @Ben - I think I am going to confuse people here with my title. This is the identifier column. In your orm entity its the one you marked as fieldtype="id". Sorry for the confusion.

• #3 by Raymond Camden on 12/21/09 - 11:46 AM

  

  But, to add to Ben's comment, I wonder if you can get more MD about the column. I wonder how much MD (sorry, metadata if that isn't clear) you can get from the session factory.

• #4 by John Whish on 12/21/09 - 11:47 AM

  

  If you use:
  
  ORMGetSessionFactory().getClassMetadata( "EntityName" ).getIdentifierColumnNames()
  
  you get an array of properties which make up the identifier.
  
  I did post some other handy methods here if anyone is interested: http://www.aliaspooryorik.com/blog/index.cfm/e/pos...

• #5 by Ben Nadel on 12/21/09 - 11:47 AM

  

  @Dan,
  
  Sorry if I muddied the waters :) Still haven't fully dove into this stuff yet.

• #6 by Dan Vega on 12/21/09 - 12:03 PM

  

  @John - This is the primary key right? Why is it called the identifier? Is there a difference?
  
  @Ben - No problem, it sparked a good conversation and I like you am just trying to learn man.

• #7 by Dan Vega on 12/21/09 - 12:08 PM

  

  @Ray - These are the 3 methods I see related to the identifier. The type returns more info about the type like sqltype and default value.
  
  getIdentifierGenerator(java.lang.String)   returns - org.hibernate.id.IdentifierGenerator
  
  getIdentifierPropertyName(java.lang.String)   returns - java.lang.String
  
  getIdentifierType(java.lang.String)   
  returns - org.hibernate.type.Type

• #8 by Justice on 12/24/09 - 7:12 PM

  

  Dan,
  
  Hibernate makes a drastic distinction between properties and columns. Java classes (and CF components) have "properties," while database tables have "columns," and Hibernate is capable of handling very complex mappings between these class properties and database columns. It is important to keep these two words clear and distinct in one's mind when thinking about Hibernate.
  
  For example, the identifier property might be mapped to two columns. And another pair of properties might be mapped to a single column.
  
  Hibernate requires a single identifier property, which can be mapped to either a unicolumn primary key or a multicolumn primary key.
  
  That's why you will see the apparent discrepancy between getIdentifierPropertyName and getIdentifierColumnNames.
  
  Cheers,
  Justice