Django-haystack: `order_by` does not work with `DecimalField`

Perhaps the best way to (quickly) address this would be to update the DecimalField documentation to indicate that order_by is not supported.

In the longer term, a WARNING leve log message could be output when the order_by operation is attempted on a DecimalField. For performance reasons, the verification of the field type could only be done when the site is in DEBUG mode.

One work-around for this is to store the contents of a decimal field as an integer. For example, if I have a model called MyModel with a Decimal field called price, I could multiply it by the number of decimal places and store as an integer.

class MyIndex(SearchIndex):
    ...
    price = IntegerField(model_attr='price')

    def prepare_price(self, obj):
        return int(obj.price * Decimal('100'))

This seems to work for elasticsearch but not for solr.

The bug apparently applies to Whoosh as well.

Range queries fail too on elasticsearch.

+1

I've hit this same issue using the SolrBackend. We are sorting by a field which contains a number between 0.0 - 1.0 representing a complex scoring algorithm. When sorting by string that means elements with a very small score are sorted above those with larger scores e.g. 9e-08

Fairly, obvious work around is to use a float field instead (doesn't really matter for my purposes).

This is pretty bad. If it's not going to be fixed, but just documented as "order_by doesn't work", then I think we should deprecate the field type or have a clear warning in the list of field types, because it would be easy to use it by mistake, and slow to repair if you have a large database.

doesn't work for elasticsearch either

:+1:

@JoeJasinski thank you so much, your answer helped me

One work-around for this is to store the contents of a decimal field as an integer. For example, if I have a model called MyModel with a Decimal field called price, I could multiply it by the number of decimal places and store as an integer.

class MyIndex(SearchIndex):
    ...
    price = IntegerField(model_attr='price')

    def prepare_price(self, obj):
        return int(obj.price * Decimal('100'))

And then?
MyIndex.objects.all().order_by('prepare_price')? Right?