sqlobject-discuss

[SQLObject] fetchAlternateID()

[Luke O. <lu...@me...>]

Not sure if i just saw a message about this, but can't find it..

modification to _SO_fetchAlternateID to deal with the situation where
there is no record with that value.

    def _SO_fetchAlternateID(cls, dbIDName, value):
        result = cls._connection._SO_selectOneAlt(
            cls,
            [cls._idName] +
            [col.dbName for col in cls._columns],
            dbIDName,
            value)
        if not result:
            raise KeyError, "The object %s by the alternate ID (%s) %s
does not exist" % (cls.__name__, dbIDName, value)
        obj = cls(result[0])
     ....

Now, this raise the question of what error to raise. We're doing a
similar check in _init() if the ID is non-existent, and KeyError
isn't exactly the right error to throw for these "no such object
exists". We're catching a generic LookupError for now for both these
cases, but I suggesting an SQLObject-specific lookup error:

class SQLObjectLookupError(LookupError):
     pass

(or maybe named NoSuchObject(LookupError) ?)

just so that catches can be more explicit and not catch other generic
Key/Lookup Errors. Thoughts? (Think of a better name for it? I
definitely think it should inherit from LookupError, and not just
Exception..)

- Luke

Re: [SQLObject] fetchAlternateID()

[Ian B. <ia...@co...>]

On Fri, 2003-04-18 at 15:44, Luke Opperman wrote:
> Not sure if i just saw a message about this, but can't find it..
> 
> modification to _SO_fetchAlternateID to deal with the situation where
> there is no record with that value.
> 
>     def _SO_fetchAlternateID(cls, dbIDName, value):
>         result = cls._connection._SO_selectOneAlt(
>             cls,
>             [cls._idName] +
>             [col.dbName for col in cls._columns],
>             dbIDName,
>             value)
>         if not result:
>             raise KeyError, "The object %s by the alternate ID (%s) %s
> does not exist" % (cls.__name__, dbIDName, value)
>         obj = cls(result[0])
>      ....

Sure, that seems right.  I've named it SQLObjectNotFound, subclass
LookupError.  At some point I'll get rid of the lazy fetching of column
data, at which point trying to instantiate a non-existant object will
raise the same exception.

  Ian