Grid/Form validation function inconsistency

[Tom Clerckx]

I think this is worth mentioning in the documentation regarding the validation function of the grid/form (and/or make code-changes). 

In web2py:

In the validation function:

• you could modify the values of the form vars 
• you could add additional form vars

In py4web:

In the validation function:

• You cannot add form vars
• You cannot assign new values to the form vars
• You can manipulate certain form vars (like a list)
• In order to change/add elements in py4web that are stored in the database, one could use one of the DAL callbacks 
  • _before_insert 
  • _before_update

In general, I would say not to use the validation function to make changes to the form data.

See code sample below (note the remarks in the validation function)

### Model

table_test_two = db.define_table('test_two',

Field('name', 'string'),

Field('number', 'list:integer'),

)

db.commit()

### Controller

def sample_two_validate(form):

# --> This does not work in py4web - whereas it worked in web2py:

# (the name stays unchanged in py4web)

form.vars['name'] = "Hellow"

# --> This works both in py4web and web2py:

form.vars['number'].append(42)

@action("sample_two")

@action("sample_two/<path:path>")

@action.uses("generic.html")

def index(path=None):

# testtwo: test validation function

grid = Grid(path,

query=(db.test_two.id > 0),

validation=sample_two_validate

)

return dict(grid=grid)