Add fuzzy lookup for text and char fields

binder/models.py

@@ -10,6 +10,7 @@
 
 from django import forms
 from django.db import models
+from django.db.models import Value
 from django.db.models.fields.files import FieldFile, FileField
 from django.contrib.postgres.fields import CITextField, ArrayField, DateTimeRangeField as DTRangeField
 from django.core import checks
@@ -29,6 +30,29 @@
 from . import history
 
 
+@models.CharField.register_lookup
+@models.TextField.register_lookup
+class FuzzyLookup(models.Lookup):
+
+	lookup_name = 'fuzzy'
+
+	def get_prep_lookup(self):
+		assert isinstance(self.rhs, str)
+		pattern = ['%']
+		for part in self.rhs.split():
+			for char in part:
+				if char in '%_[\\':
+					char.append('\\')
+				pattern.append(char)
+			pattern.append('%')
+		return Value(''.join(pattern))
+
+	def as_sql(self, compiler, connection):
+		lhs, lhs_params = self.process_lhs(compiler, connection)
+		rhs, rhs_params = self.process_rhs(compiler, connection)
+		return f'{lhs} ilike {rhs} escape \'\\\'', (*lhs_params, *rhs_params)
+
+
 class DateTimeRangeField(DTRangeField):
 
 	default_error_messages = {
@@ -347,7 +371,7 @@ def clean_value(self, qualifier, v):
 
 class TextFieldFilter(FieldFilter):
 	fields = [models.CharField, models.TextField]
-	allowed_qualifiers = [None, 'in', 'iexact', 'contains', 'icontains', 'startswith', 'istartswith', 'endswith', 'iendswith', 'exact', 'isnull']
+	allowed_qualifiers = [None, 'in', 'iexact', 'contains', 'icontains', 'startswith', 'istartswith', 'endswith', 'iendswith', 'exact', 'isnull', 'fuzzy']
 
 	# Always valid(?)
 	def clean_value(self, qualifier, v):

tests/filters/test_text_filters.py

@@ -0,0 +1,51 @@
+import unittest, os
+
+from django.test import TestCase, Client
+from django.contrib.auth.models import User
+
+from binder.json import jsonloads
+
+from ..testapp.models import Zoo
+
+
+@unittest.skipIf(
+	os.environ.get('BINDER_TEST_MYSQL', '0') != '0',
+	"Only available with PostgreSQL"
+)
+class TextFiltersTest(TestCase):
+
+    def setUp(self):
+        super().setUp()
+        u = User(username='testuser', is_active=True, is_superuser=True)
+        u.set_password('test')
+        u.save()
+
+        self.client = Client()
+        r = self.client.login(username='testuser', password='test')
+        self.assertTrue(r)
+
+        Zoo(name='Burgers Zoo').save()
+        Zoo(name='Artis').save()
+        Zoo(name='Apenheul').save()
+        Zoo(name='Ouwehand Zoo').save()
+
+    def test_filter_fuzzy(self):
+        response = self.client.get('/zoo/', data={'.name:fuzzy': 'b zo'})
+        self.assertEqual(response.status_code, 200)
+        result = jsonloads(response.content)
+        self.assertEqual(1, len(result['data']))
+        self.assertEqual('Burgers Zoo', result['data'][0]['name'])
+
+        response = self.client.get('/zoo/', data={'.name:fuzzy': '  zo  '})
+        self.assertEqual(response.status_code, 200)
+        result = jsonloads(response.content)
+        self.assertEqual(2, len(result['data']))
+        self.assertEqual('Burgers Zoo', result['data'][0]['name'])
+        self.assertEqual('Ouwehand Zoo', result['data'][1]['name'])
+
+        response = self.client.get('/zoo/', data={'.name:fuzzy': 'ar'})
+        self.assertEqual(response.status_code, 200)
+        result = jsonloads(response.content)
+        self.assertEqual(response.status_code, 200)
+        self.assertEqual(1, len(result['data']))
+        self.assertEqual('Artis', result['data'][0]['name'])