is there any sort of find_or_create query?

[CoolAJ86]

If I have an object User in rails with attributes first, last, and
password I can do something like this

user = {:first => 'John', :last => 'Doe'} # a dict-like object
user = Users.find_or_create(user)

is there any such convenience method in sqlalchemy?

[AJ ONeal]

It looks like the answer to my question is no.

Is there any add-on (Elixer or whatever) which has a shortcut method like what I'm asking?

I did find that "insert_or_update" is not the solution.

I also found an appropriate, but longer way to read or create:

page = Session.query(Page).filter(Page.url == url, Page.body==body).first() 

if not page: 

  page = Page(url = url, body=body) 

  session.save(page)

If you know the primary key identifiers of the object, you may also use merge():

page = Page(<primary key identifiers>) 

  persisted_page = Session.merge(page)

the latter will do the same thing automatically as the former (SQLA does not use IntegrityErrors to query the database).

AJ ONeal

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[AJ ONeal]

Actually the answer is yes.

merge() reconciles the current state of an instance and its associated children with existing data in the database, and returns a copy of the instance associated with the session. Usage is as follows:

merged_object = session.merge(existing_object)

When given an instance, it follows these steps:

• It examines the primary key of the instance. If it’s present, it attempts to load an instance with that primary key (or pulls from the local identity map).
• If there’s no primary key on the given instance, or the given primary key does not exist in the database, a new instance is created.
• The state of the given instance is then copied onto the located/newly created instance.
• The operation is cascaded to associated child items along the merge cascade. Note that all changes present on the given instance, including changes to collections, are merged.
• The new instance is returned.

Generically the pattern is called: insert_or_update

SQLAlchemy calls it: merge

Rails calls it: find_or_create

Symfony implements it as: setNew(false) and then save()

MySql calls it: insert on duplicate update

AJ ONeal

[Nebur]

AJ, thanks for the monologue ;-)
It reads like a good overview.