Web2py - How to update a table field appending a string to an existing field value

[Meinolf]

Hi there

So far i only know how to update a record by replacing the old field value with the new value. Suppose i want to append the search_term string value the corresponding text field so that both values are stored, how can i do that in this code:

myrow = db((db.rated_items.user_id==auth.user.id) &  (db.rated_items.item_id==request.args(0))).update(search_term=str(request.vars.search_term)

Would appreciate any help!!

[Massimo Di Pierro]

This should work for appending strings to strings (not to lists of strings):

myrow = db((db.rated_items.user_id==auth.user.id) &  (db.rated_items.item_id==request.args(0))).update(search_term=db.rated_items.search_term+str(request.vars.search_term)

[Meinolf]

I had tried that and tried it just now but still gives a None value in the rated_items.search_term field. maybe it's got to do with the table def; my table definition is as follows:

db.define_table('rated_items',

    Field('search_term','string'),

    Field('user_id', 'reference auth_user', default=auth.user and auth.user.id),

    Field('item_id', 'integer'),

    Field('clicks', 'integer', default=0),

    migrate=True,

    )

[Massimo Di Pierro]

This works for me, I just tried:

>>> db.define_table('rated_items',

    Field('search_term','string'),

    )

>>> k = db.rated_items.insert(search_term='a')

>>> db(db.rated_items.id==k).update(search_term=db.rated_items.search_term+'b')

>>> print db.rated_items[k]

<Row {'search_term': 'ab', 'id': 1L}>

you probably have None into the search_term field and it cannot be concatenated with string.

[Meinolf]

Excellent, the None value was indeed the problem, so i just gave a default string value in the table definition as Field('search_term', 'string', default='') and now it works. Thanks a lot.