@@ -113,9 +113,89 @@ Options
113113
114114 The ``fields `` option was introduced in Symfony 6.1.
115115
116- This is optional and defines key or keys
117- in a collection that should be checked for uniqueness.
118- By default, all collection keys are checked for uniqueness.
116+ This is defines the key or keys in a collection that should be checked for
117+ uniqueness. By default, all collection keys are checked for uniqueness.
118+
119+ For instance, assume you have a collection of items that contain a
120+ ``latitude ``, ``longitude `` and ``label `` fields. By default, you can have
121+ duplicate coordinates as long as the label is different. By setting the
122+ ``fields `` option, you can force latitude+longitude to be unique in the
123+ collection::
124+
125+ ..configuration-block ::
126+
127+ ..code-block ::php-annotations
128+
129+ // src/Entity/Poi.php
130+ namespace App\Entity;
131+
132+ use Symfony\Component\Validator\Constraints as Assert;
133+
134+ class Poi
135+ {
136+ /**
137+ * @Assert\Unique(fields={"latitude", "longitude"})
138+ */
139+ protected $coordinates;
140+ }
141+
142+ code-block ::php-attributes
143+
144+ // src/Entity/Poi.php
145+ namespace App\Entity;
146+
147+ use Symfony\Component\Validator\Constraints as Assert;
148+
149+ class Poi
150+ {
151+ #[Assert\Unique(fields=['latitude', 'longitude'])]
152+ protected $coordinates;
153+ }
154+
155+ code-block ::yaml
156+
157+ # config/validator/validation.yaml
158+ App\Entity\Poi :
159+ properties :
160+ contactEmails :
161+ -Unique :
162+ fields :[latitude, longitude]
163+
164+ code-block ::xml
165+
166+ <!-- config/validator/validation.xml-->
167+ <?xml version =" 1.0" encoding =" UTF-8"
168+ <constraint-mapping xmlns =" http://symfony.com/schema/dic/constraint-mapping"
169+ xmlns : xsi =" http://www.w3.org/2001/XMLSchema-instance"
170+ xsi : schemaLocation =" http://symfony.com/schema/dic/constraint-mapping https://symfony.com/schema/dic/constraint-mapping/constraint-mapping-1.0.xsd"
171+
172+ <class name =" App\Entity\Poi"
173+ <property name =" coordinates"
174+ <constraint name =" Unique"
175+ <field >latitude</field >
176+ <field >longitude</field >
177+ </constraint >
178+ </property >
179+ </class >
180+ </constraint-mapping >
181+
182+ code-block ::php
183+
184+ // src/Entity/Poi.php
185+ namespace App\Entity;
186+
187+ use Symfony\Component\Validator\Constraints as Assert;
188+ use Symfony\Component\Validator\Mapping\ClassMetadata;
189+
190+ class Poi
191+ {
192+ public static function loadValidatorMetadata(ClassMetadata $metadata)
193+ {
194+ $metadata->addPropertyConstraint('contactEmails', new Assert\Unique([
195+ 'fields' => ['latitude', 'longitude'],
196+ ]));
197+ }
198+ }
119199
120200include ::/reference/constraints/_groups-option.rst.inc
121201