Re: [SQLObject] SingleJoin help

[Darren G. <da...@on...>]

I think I figured this out. The it seems to matter what class has the
foreign key so special attention needed there. In my case.

> class DataRow(SQLObject):
>      type = StringCol()
>      data  = BLOBCol(length=2**24)
>      text = UnicodeCol()
>      row = ForeignKey('ProcessRow')

class DataRow(SQLObject):
     type = StringCol()
     data  = BLOBCol(length=2**24)
     text = UnicodeCol()
     row = SingleJoin('ProcessRow')

and

>class ProcessRow(SQLObject):
>      path = StringCol()
>      status = StringCol()
>      data = SingleJoin('DataRow')
> 
class ProcessRow(SQLObject):
     path = StringCol()
     status = StringCol()
     data = ForeignKey('DataRow')

This now works correctly:

    r = ProcessRow.get(1)
    print "STATUS:"+r.status
    print "DATA:"+r.data.type


The other direction didn't work when retrieving ProcessRow and referring
to DataRow.

Maybe the documentation can mention something about this cardinality for
One-to-One mapping more clearly. Just a thought!

Darren

On Fri, 2008-11-14 at 09:08 -0500, Darren Govoni wrote:
> Hi,
>   I read the documentation and it briefly mentions SingleJoin, but gives
> no example. 
> 
> I tried to use ForeignKey in the referenced class and SingleJoin in the
> primary class, but I get this error when retrieving.
> 
> AttributeError: DataRow instance has no attribute 'processRowID'
> 
> My classes are simple.
> 
> class DataRow(SQLObject):
>      type = StringCol()
>      data  = BLOBCol(length=2**24)
>      text = UnicodeCol()
>      row = ForeignKey('ProcessRow')
> 
> class ProcessRow(SQLObject):
>      path = StringCol()
>      status = StringCol()
>      data = SingleJoin('DataRow')
> 
> r = ProcessRow(path='here',status='loading')
> datar=DataRow(data=d,type='binary',text='',row=r)
> 
> I'm not sure how to set the 'data' attribute for a ProcessRow since
> both classes refer to each other. The DataRow SQL entry has a correct
> row_id column set, but when I try to read it back like this, gives
> error.
> 
>     r = ProcessRow.get(1)
>     print "STATUS:"+r.status
>     print "DATA:"+r.data.type   <<<<< generates error
> 
> 
> thank you.
> Darren
> 
> 
> 
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