id	summary	reporter	owner	description	type	status	component	version	severity	resolution	keywords	cc	stage	has_patch	needs_docs	needs_tests	needs_better_patch	easy	ui_ux
7485	OtherField validators don't work with inline child objects	slinkp@…	nobody	"If you have a child model that references a parent model as a foreign key, and edit them inline in the django admin UI, you can't use any of the *OtherField validators such as IsLessThanOtherField.

The reason is that these validators expect the other_key parameter to be the exact name of the relevant form field; but with ForeignKey(edit_inline=...), the name is mangled.

I tried this workaround - but see the inline comments for why it's wrong:

{{{

class IsGreaterThanOtherField:
    """"""Django defines an IsLessThanOtherField validator,
    but it doesn't work on one-to-many children because the
    keys have some name-mangling going on.
    """"""

    def __init__(self, other_field):
        self.other_field = other_field

    def __call__(self, field_data, all_data):
        # We have to iterate over them because we don't know the name of
        # our own field.
        for key, val in sorted(all_data.items()):
            if val == field_data:
                # Hope and pray there's no duplicate values.
                # If there are, this validator will only work for the first row.
                # The remaining rows will incorrectly compare against other_field from the first row.
                modelname, pkey, fieldname = key.split('.')
                myval = val
                break
        otherkey = '.'.join([modelname, pkey, self.other_field])
        if myval <= all_data[otherkey]:
            raise validators.ValidationError(
                ""Must be greater than the value of %s"" % self.other_field)

}}}

I can't think of any way to work around this limitation, because the validator API doesn't provide any way that I see to know the actual name of the field we're validating.
"		closed	contrib.admin	0.96		invalid			Design decision needed	0	0	0	0	0	0