fix: only check minProperties or maxProperties on objects (#802)

`minProperties` and `maxProperties` are only applicable on objects.

https://www.learnjsonschema.com/draft4/validation/minproperties/ 

https://json-schema.org/draft-04/draft-fge-json-schema-validation-00#rfc.section.5.4.2

Author: DannyvdSluijs

CHANGELOG.md

@@ -6,6 +6,8 @@ The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.1.0/),
 and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0.html).
 
 ## [Unreleased]
+### Fixed
+- only check minProperties or maxProperties on objects ([#802](https://github.com/jsonrainbow/json-schema/pull/802))
 
 ## [6.2.1] - 2025-03-06
 ### Fixed

src/JsonSchema/Constraints/ObjectConstraint.php

@@ -175,15 +175,19 @@ protected function &getProperty(&$element, $property, $fallback = null)
      */
     protected function validateMinMaxConstraint($element, $objectDefinition, ?JsonPointer $path = null)
     {
+        if (!$this->getTypeCheck()::isObject($element)) {
+            return;
+        }
+
         // Verify minimum number of properties
-        if (isset($objectDefinition->minProperties) && !is_object($objectDefinition->minProperties)) {
-            if ($this->getTypeCheck()->propertyCount($element) < $objectDefinition->minProperties) {
+        if (isset($objectDefinition->minProperties) && is_int($objectDefinition->minProperties)) {
+            if ($this->getTypeCheck()->propertyCount($element) < max(0, $objectDefinition->minProperties)) {
                 $this->addError(ConstraintError::PROPERTIES_MIN(), $path, ['minProperties' => $objectDefinition->minProperties]);
             }
         }
         // Verify maximum number of properties
-        if (isset($objectDefinition->maxProperties) && !is_object($objectDefinition->maxProperties)) {
-            if ($this->getTypeCheck()->propertyCount($element) > $objectDefinition->maxProperties) {
+        if (isset($objectDefinition->maxProperties) && is_int($objectDefinition->maxProperties)) {
+            if ($this->getTypeCheck()->propertyCount($element) > max(0, $objectDefinition->maxProperties)) {
                 $this->addError(ConstraintError::PROPERTIES_MAX(), $path, ['maxProperties' => $objectDefinition->maxProperties]);
             }
         }

tests/Constraints/MinMaxPropertiesTest.php

@@ -9,6 +9,8 @@
 
 namespace JsonSchema\Tests\Constraints;
 
+use JsonSchema\Constraints\Constraint;
+
 class MinMaxPropertiesTest extends BaseTestCase
 {
     protected $validateSchema = true;
@@ -19,50 +21,71 @@ class MinMaxPropertiesTest extends BaseTestCase
     public function getValidTests(): array
     {
         return [
-            [
-                '{
+            'Empty object with minProperties: 0' => [
+                'input' => '{
                   "value": {}
                 }',
-                '{
+                'schema' => '{
                   "type": "object",
                   "properties": {
                     "value": {"type": "object", "minProperties": 0}
                   }
                 }'
             ],
-            [
-                '{
+            'Empty object with maxProperties: 1' => [
+                'input' => '{
                   "value": {}
                 }',
-                '{
+                'schema' => '{
                   "type": "object",
                   "properties": {
                     "value": {"type": "object", "maxProperties": 1}
                   }
                 }'
             ],
-            [
-                '{
+            'Empty object with minProperties: 0 and maxProperties: 1' => [
+                'input' => '{
                   "value": {}
                 }',
-                '{
+                'schema' => '{
                   "type": "object",
                   "properties": {
                     "value": {"type": "object", "minProperties": 0,"maxProperties": 1}
                   }
                 }'
             ],
-            [
-                '{
+            'Object with two properties with minProperties: 1 and maxProperties: 2' => [
+                'input' => '{
                   "value": {"foo": 1, "bar": 2}
                 }',
-                '{
+                'schema' => '{
                   "type": "object",
                   "properties": {
                     "value": {"type": "object", "minProperties": 1,"maxProperties": 2}
                   }
                 }'
             ],
+            'Empty array with minProperties: 1 and maxProperties: 2' => [
+                'input' => '{
+                  "value": []
+                }',
+                'schema' => '{
+                  "properties": {
+                    "value": {"minProperties": 1,"maxProperties": 2}
+                  }
+                }',
+                'checkMode' => Constraint::CHECK_MODE_NORMAL,
+            ],
+            'Array with two items with maxProperties: 1' => [
+                'input' => '{
+                  "value": [1, 2]
+                }',
+                'schema' => '{
+                  "properties": {
+                    "value": {"maxProperties": 1}
+                  }
+                }'
+            ],
         ];
     }
 
@@ -72,20 +95,20 @@ public function getValidTests(): array
     public function getInvalidTests(): array
     {
         return [
-            [
-                '{
+            'Empty object with minProperties: 1' => [
+                'input' => '{
                   "value": {}
                 }',
-                '{
+                'schema' => '{
                   "type": "object",
                   "properties": {
                     "value": {"type": "object", "minProperties": 1}
                   }
                 }'
             ],
-            [
-                '{}',
-                '{
+            'Empty object with minProperties' => [
+                'input' => '{}',
+                'schema' => '{
                   "type": "object",
                   "properties": {
                     "propertyOne": {
@@ -98,41 +121,31 @@ public function getInvalidTests(): array
                   "minProperties": 1
                 }'
             ],
-            [
-                '{
+            'Object with two properties with maxProperties: 1' => [
+                'input' => '{
                   "value": {
                     "propertyOne": "valueOne",
                     "propertyTwo": "valueTwo"
                   }
                 }',
-                '{
+                'schema' => '{
                   "type": "object",
                   "properties": {
                     "value": {"type": "object", "maxProperties": 1}
                   }
                 }'
             ],
-            [
-                '{
+            'Object with two properties with minProperties: 1 and maxProperties: 2' => [
+                'input' => '{
                   "value": {"foo": 1, "bar": 2, "baz": 3}
                 }',
-                '{
+                'schema' => '{
                   "type": "object",
                   "properties": {
                     "value": {"type": "object", "minProperties": 1,"maxProperties": 2}
                   }
                 }'
             ],
-            [
-                '{
-                  "value": []
-                }',
-                '{
-                  "properties": {
-                    "value": {"minProperties": 1,"maxProperties": 2}
-                  }
-                }'
-            ],
         ];
     }
 }