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.. _term-boost-label:
Term Boost
==========
.. warning::
**BIG FAT WARNING**
As far as I can see, the term boost functionality is implemented by the specs in the
`Haystack documentation <https://django-haystack.readthedocs.io/en/v2.4.0/boost.html#term-boost>`_,
however it does not really work as it should!
When applying term boost, results are discarded from the search result, and not re-ordered by
boost weight as they should.
These are known problems and there exists open issues for them:
- https://github.com/inonit/drf-haystack/issues/21
- https://github.com/django-haystack/django-haystack/issues/1235
- https://github.com/django-haystack/django-haystack/issues/508
**Please do not use this unless you really know what you are doing!**
(And please let me know if you know how to fix it!)
Term boost is achieved on the SearchQuerySet level by calling ``SearchQuerySet().boost()``. It is
implemented as a :class:`drf_haystack.filters.HaystackBoostFilter` filter backend.
The ``HaystackBoostFilter`` does not perform any filtering by itself, and should therefore be combined with
some other filter that does, for example the :class:`drf_haystack.filters.HaystackFilter`.
.. code-block:: python
from drf_haystack.filters import HaystackBoostFilter
class SearchViewSet(HaystackViewSet):
...
filter_backends = [HaystackFilter, HaystackBoostFilter]
The filter expects the query string to contain a ``boost`` parameter, which is a comma separated string
of the term to boost and the boost value. The boost value must be either an integer or float value.
**Example query**
.. code-block:: none
/api/v1/search/?firstname=robin&boost=hood,1.1
The query above will first filter on ``firstname=robin`` and next apply a slight boost on any document containing
the word ``hood``.
.. note::
Term boost are only applied on terms existing in the ``document field``.
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