Grid: New (create) form validation problem

[Jumbleoak]

I am trying to validate a field. In models.py I have:

db.define_table(
    "weather",
    Field("temp"),
    etc.
)

db.weather.temp.requires = IS_EMPTY_OR(
IS_DECIMAL_IN_RANGE(-99, 99, dot=".", error_message='must be empty or a number from -99 to 99'))

The problem I have is that by introducing that validation the form displays '0.00' by default
whereas I want it to display nothing (and then by allowing that default of 0.00 to post it
results in 0.00 being posted to the underlying table - as expected).

In other words, I want the user to be able to enter a decimal from -99..0..99, and I want to validate any entry they do make, but I also want to be able to post NULL if they do not enter anything themselves.

(I confirm that the underlying mariadb table will accept NULL in the corresponding decimal field. I also confirm that I am new to py4web and python!)

Many thanks

Max

[Massimo DiPierro]

Can you please open a ticket about this. It looks like a bug in the IS_EMPTY_OR validator.

[Jumbleoak]

Hi,

I held back on the ticket because just to be more precise:

Used by itself, IS_DECIMAL_IN_RANGE() will insert a default value of '.00' in the form entry field. If that is left as the submitted value and it is is in range, as with minimum=-99, maximum=99, then 0 gets posted thru to the database. If the user deletes that default value, leaving the entry field blank, then the out of range error message is displayed. That is all as expected, except possibly for the initial insertion of '.00'.

If IS_EMPTY_OR(IS_DECIMAL_IN_RANGE()) is used, then a default value of '.00' is still inserted in the form entry field.  If that is left as the submitted value and it is is in range, as with minimum=-99, maximum=99, then 0 gets posted thru to the database. But, if the user deletes that default value, leaving the entry field blank, then None/null gets posted thru to the database. This is also all as expected, except possibly  for the initial insertion of '.00'.

I don't know if it is actually an issue that IS_DECIMAL_IN_RANGE() inserts a default value of '.00'. But if it is not, then my question boils down to: Is there any way to to start with a blank entry field, and on submission validate that the final entry is in [blank/None/null, -99..0..99]?

(Just so I don't waste anyone's time, I can now do this with a custom validator, but it isn't pretty)

Thank you.

[Massimo DiPierro]

I think the behavior should be:

1) IS_DECIMAL_IN_RANGE should prefill with 0 if 0 is in between range, else should use the minimum value

2) IS_EMPTY_OR(...) should never have a prefill value

I suspect anyway, that the prefill value comes from Field("name", "decimal", ..., default=0.0)

Have you tried Field("name", "decimal", ..., default=None)?

[Jumbleoak]

Hi,

Yes, I tried Field("name", "decimal", ..., default=None), with and without "decimal", with both IS_DECIMAL_IN_RANGE() and IS_EMPTY_OR(IS_DECIMAL_IN_RANGE()) and the prefill is '.00' in all cases.

So, if IS_EMPTY_OR() is supposed to overwrite or otherwise prevent the prefill from IS_DECIMAL_IN_RANGE(), then it does not appear to be doing that. On that basis I could open an issue.

Thank you.