Commit 1962a96a authored by Matthew Somerville's avatar Matthew Somerville Committed by Tim Graham
Browse files

Fixed #24938 -- Added PostgreSQL trigram support.

parent d7334b40

django/contrib/postgres/apps.py

+3 −1
Original line number Diff line number Diff line
@@ -3,7 +3,7 @@ from django.db.backends.signals import connection_created 
from django.db.models import CharField, TextField

from django.utils.translation import ugettext_lazy as _



from .lookups import SearchLookup, Unaccent

from .lookups import SearchLookup, TrigramSimilar, Unaccent

from .signals import register_hstore_handler
@@ -17,3 +17,5 @@ class PostgresConfig(AppConfig): 
        TextField.register_lookup(Unaccent)

        CharField.register_lookup(SearchLookup)

        TextField.register_lookup(SearchLookup)

        CharField.register_lookup(TrigramSimilar)

        TextField.register_lookup(TrigramSimilar)

django/contrib/postgres/lookups.py

+5 −0
Original line number Diff line number Diff line
@@ -60,3 +60,8 @@ class SearchLookup(SearchVectorExact): 
            self.lhs = SearchVector(self.lhs)

        lhs, lhs_params = super(SearchLookup, self).process_lhs(qn, connection)

        return lhs, lhs_params





class TrigramSimilar(PostgresSimpleLookup):

    lookup_name = 'trigram_similar'

    operator = '%%'

django/contrib/postgres/operations.py

+6 −0
Original line number Diff line number Diff line
@@ -40,3 +40,9 @@ class UnaccentExtension(CreateExtension): 


    def __init__(self):

        self.name = 'unaccent'





class TrigramExtension(CreateExtension):



    def __init__(self):

        self.name = 'pg_trgm'

django/contrib/postgres/search.py

+16 −0
Original line number Diff line number Diff line
@@ -185,3 +185,19 @@ class SearchRank(Func): 




SearchVectorField.register_lookup(SearchVectorExact)





class TrigramBase(Func):

    def __init__(self, expression, string, **extra):

        if not hasattr(string, 'resolve_expression'):

            string = Value(string)

        super(TrigramBase, self).__init__(expression, string, output_field=FloatField(), **extra)





class TrigramSimilarity(TrigramBase):

    function = 'SIMILARITY'





class TrigramDistance(TrigramBase):

    function = ''

    arg_joiner = ' <-> '

docs/ref/contrib/postgres/lookups.txt

+26 −0
Original line number Diff line number Diff line
@@ -2,6 +2,32 @@ 
PostgreSQL specific lookups

===========================



Trigram similarity

==================



.. fieldlookup:: trigram_similar



.. versionadded:: 1.10



The ``trigram_similar`` lookup allows you to perform trigram lookups,

measuring the number of trigrams (three consecutive characters) shared, using a

dedicated PostgreSQL extension. A trigram lookup is given an expression and

returns results that have a similarity measurement greater than the current

similarity threshold.



To use it, add ``'django.contrib.postgres'`` in your :setting:`INSTALLED_APPS`

and activate the `pg_trgm extension

<http://www.postgresql.org/docs/current/interactive/pgtrgm.html>`_ on

PostgreSQL. You can install the extension using the

:class:`~django.contrib.postgres.operations.TrigramExtension` migration

operation.



The ``trigram_similar`` lookup can be used on

:class:`~django.db.models.CharField` and :class:`~django.db.models.TextField`::



    >>> City.objects.filter(name__trigram_similar="Middlesborough")

    ['<City: Middlesbrough>']



``Unaccent``

============