#27147: Add support for defining bounds in postgres range fields
-------------------------------------+-------------------------------------
Reporter: Kirill Stepanov | Owner: (none)
Type: New feature | Status: new
Component: contrib.postgres | Version: master
Severity: Normal | Resolution:
Keywords: postgres range | Triage Stage: Accepted
bounds |
Has patch: 0 | Needs documentation: 0
Needs tests: 0 | Patch needs improvement: 0
Easy pickings: 0 | UI/UX: 0
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Comment (by Matthew Schinckel):
There's two parts: ensuring that the user-entered-data is upper-bounds-
inclusive, and ensuring that the saved data is presented back to the user
as upper-bounds-inclusive.
The first part of this is trivial - just have a bounds value of '[]'
passed in to the constructor. In my case, I have an InclusiveRangeMixin
that does this in compress.
The second part is less clear - because in the case of distinct range
types there is a "unit value" that needs to be removed from the upper
bounds, but in the case of continuous ranges, this is not possible (but in
that case, postgres will not have normalised it, so it's all good).
Anyway, code speaks louder than words here, so here's how I've approached
this in the past:
{{{
class InclusiveRangeMixin(object):
_unit_value = None
def compress(self, values):
range_value = super(InclusiveRangeMixin, self).compress(values)
if range_value:
return self.range_type(range_value.lower, range_value.upper,
bounds='[]')
def prepare_value(self, value):
value = super(InclusiveRangeMixin, self).prepare_value(value)
# We need to clean both fields.
value = [field.clean(val) for field, val in zip(self.fields,
value)]
if value[1] is not None:
value[1] = value[1] - self._unit_value
return value
class InclusiveDateRangeField(InclusiveRangeMixin, DateRangeField):
_unit_value = datetime.timedelta(1)
class InclusiveIntegerRangeField(InclusiveRangeMixin, IntegerRangeField):
_unit_value = 1
}}}
--
Ticket URL: <https://code.djangoproject.com/ticket/27147#comment:5>
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