Friday, October 27, 2006

Okey, things I miss about NHibernate

Lately I have been working without a formal object relational mapping (you know, using custom "hand made" business objects, and fetching data from the database using stored procedures)

Here are the things I miss from NHibernate:

  • Automatic caching of objects by primary key
  • Easy support for primary keys with multiple fields
  • Polymorphic Queries (and all the benefits of persistent inheritance)
  • Queries with "." navigation "object.Relationship.Relationship.Field = :parameter"
  • Prefecthing relationships: "load Products with their to one relationship with Vendor preloaded"
  • Easy pagination (instead of trying to figure out how to do it in combination with stored procedures for a particular version of a particular database (that can be a real nightmare))
  • Interactive single and multicolumn sorting (try to do it with stored procedures, and of course without cheating by using the execute command, remember if you use execute all the so called "security benefits" of stored procedures vs dynamic sql dissapear)
  • Concurrency support (automatical increment of a "version" field when saving changes, even if those changes are not just field changes, but relationship changes, custom exception type for concurrency errors, optimistic locking)
  • Query by example (no need to concatenate strings by hand based on whether a field is null, no need to worry about upper case or lower case comparision when comparing each field, no need to update a query definition if a column is added or dropped from a table)

And, if somehow you have to work with a database that doesn't have support for stored procedures (and you can't use NHibernate)... things get even more "interesting":

  • Alias for ugly table names and ugly field names (instead of "select * from PDT where PCKT = 1" you write "select * from Products where PackageType = 1"
  • Named Parameters: Instead of "select * from PDT where PCKT = ? and RQTY = ?" you can write: "select * from Products where PackageType= :packageType and RemainingQuantity = :remainingQuantity" this is specially a nightmare when one has to use OleDb, and it gets worse with Inserts or Updates: "INSERT INTO PDT (NN,PCKT,RQTY,DRP,PRNBR) VALUES (?,?,?,?,?)" instead of the simple: "session.save(product)"

I will update this list as it increases...

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