Can't enter scientific notation in decimal fields

[gregthe1]

Here is an example:

>>> from django.forms import DecimalField
>>> f = DecimalField(max_digits=10, decimal_places=1)
>>> f.validate(Decimal('1E+2'))
Traceback (most recent call last):
...
ValidationError: [u'Ensure that there are no more than 1 decimal places.']

Also if I try upping the max_digits and decimal_places to something like 20, and 13, I get this error:

quantize result has too many digits for current context

[Carl Meyer]

The validation issue is a bug in DecimalField. DecimalField calls value.as_tuple() and unconditionally takes the absolute value of the third argument (exponent) as the number of decimal places. This is just wrong, because it's perfectly valid for exponent to be positive, and in that case it doesn't represent a number of decimal places at all, it represents trailing zeros.

The other issue (quantize error) I can't reproduce and I don't think is related. Please open as a separate ticket with full reproduction instructions (including version of Python, since that's an error coming directly from Python's decimal module).

[Aymeric Augustin]

It should be fairly easy to convert the example given in the description of the ticket into a test case.

[samufuentes]

The second file includes tests

[Aymeric Augustin]

I suggest the following changes to the patch, by order of decreasing importance.

You should use TestCase from django.utils.unittest, which is already imported, and not from django.test, since you're not using the extra features of django.test.TestCase.

            f.validate(Decimal('1E+2'))  # Ensure that scientific notation with positive exponent is accepted (#15775)

would be more readable as:

            # regression test for #15775: scientific notation with positive exponent is valid
            f.validate(Decimal('1E+2'))

You may try to re-wrap a bit django/forms/fields.py. It's hard to read 140-chars lines — the coding rules recommend wrapping at 80 chars.

You're missing a \n at the end of the file (look at your patch in Trac).

[Bruno Gola]

applied (some of) the changes proposed

[anonymous]

I still don't think this is correct. Using the patch, it doesn't work for 1E+4.

>>> f = DecimalField(max_digits=10, decimal_places=1)
>>> f.validate(Decimal('1E+4'))
Traceback (most recent call last):
...
ValidationError: [u'Ensure that there are no more than 1 decimal places.']

[anonymous]

Sorry, disregard my last comment. I was using the wrong version.

[Claude Paroz <claude@…>]

In 58afd30b593fbd1e3d17c1bba83597da07bdb5f5:

Tested DecimalField with scientific notation

Refs #15775.

[Claude Paroz]

Seems the issue has been fixed since. I added a test to confirm that.