diff --git a/src/Fields/BaseField.php b/src/Fields/BaseField.php
index 3be621e..d306033 100644
--- a/src/Fields/BaseField.php
+++ b/src/Fields/BaseField.php
@@ -292,30 +292,27 @@ protected function checkMaximumConstraint($val, $maxConstraint)
         return $val <= $maxConstraint;
     }
 
-    protected function checkMinLengthConstraint($val, $minLength)
+    protected function getLengthForConstraint($val)
     {
         if (is_string($val)) {
-            return strlen($val) >= $minLength;
+            return strlen($val);
         } elseif (is_array($val)) {
-            return count($val) >= $minLength;
+            return count($val);
         } elseif (is_object($val)) {
-            return count($val) >= $minLength;
+            return count((array)$val);
         } else {
-            throw $this->getValidationException('invalid value for minLength constraint', $val);
+            throw $this->getValidationException('invalid value for length constraint', $val);
         }
     }
 
+    protected function checkMinLengthConstraint($val, $minLength)
+    {
+        return $this->getLengthForConstraint($val) >= $minLength;
+    }
+
     protected function checkMaxLengthConstraint($val, $maxLength)
     {
-        if (is_string($val)) {
-            return strlen($val) <= $maxLength;
-        } elseif (is_array($val)) {
-            return count($val) <= $maxLength;
-        } elseif (is_object($val)) {
-            return count($val) <= $maxLength;
-        } else {
-            throw $this->getValidationException('invalid value for maxLength constraint', $val);
-        }
+        return $this->getLengthForConstraint($val) <= $maxLength;
     }
 
     protected function getAllowedValues()
diff --git a/tests/FieldTypesTest.php b/tests/FieldTypesTest.php
index c163c70..fe342c4 100644
--- a/tests/FieldTypesTest.php
+++ b/tests/FieldTypesTest.php
@@ -19,23 +19,23 @@ public function testAny()
             ['default', '3.14', '3.14'],
             ['default', true, true],
             ['default', '', ''],
-            [(object) ['format' => 'default', 'constraints' => (object) ['required' => true]],
+            [['format' => 'default', 'constraints' => ['required' => true]],
                 null, null, ], // any field has no empty value, so required without enum is meaningless
-            [(object) [
+            [[
                 'format' => 'default',
-                'constraints' => (object) ['required' => true, 'enum' => ['test', 1, false]],
+                'constraints' => ['required' => true, 'enum' => ['test', 1, false]],
             ], null, self::ERROR],
-            [(object) [
+            [[
                 'format' => 'default',
-                'constraints' => (object) ['required' => true, 'enum' => ['test', 1, false]],
+                'constraints' => ['required' => true, 'enum' => ['test', 1, false]],
             ], 'FOO', self::ERROR],
-            [(object) [
+            [[
                 'format' => 'default',
-                'constraints' => (object) ['required' => true, 'enum' => ['test', 1, false]],
+                'constraints' => ['required' => true, 'enum' => ['test', 1, false]],
             ], false, false],
-            [(object) [
+            [[
                 'format' => 'default',
-                'constraints' => (object) ['required' => true, 'enum' => ['test', 1, null, false]],
+                'constraints' => ['required' => true, 'enum' => ['test', 1, null, false]],
             ], null, null],
         ]);
     }
@@ -47,42 +47,42 @@ public function testArray()
             ['default', '[]', []],
             ['default', ['key', 'value'], ['key', 'value']],
             ['default', '["key", "value"]', ['key', 'value']],
-            ['default', (object) ['key' => 'value'], self::ERROR],
+            ['default', (object)['key' => 'value'], self::ERROR],
             ['default', '{"key": "value"}', self::ERROR],
             ['default', 'string', self::ERROR],
             ['default', 1, self::ERROR],
             ['default', '3.14', self::ERROR],
             ['default', '', self::ERROR],  // missingValues is handled at the schema level
             // required
-            [(object) ['format' => 'default', 'constraints' => (object) ['required' => true]],
+            [['format' => 'default', 'constraints' => ['required' => true]],
                 null, self::ERROR, ],
-            [(object) ['format' => 'default', 'constraints' => (object) ['required' => true]],
+            [['format' => 'default', 'constraints' => ['required' => true]],
                 [], [], ],
             // enum
-            [(object) [
-                'format' => 'default', 'constraints' => (object) ['enum' => [[1, 2], ['foo', 'bar']]],
+            [[
+                'format' => 'default', 'constraints' => ['enum' => [[1, 2], ['foo', 'bar']]],
             ], [], self::ERROR],
-            [(object) [
-                'format' => 'default', 'constraints' => (object) [
+            [[
+                'format' => 'default', 'constraints' => [
                     'required' => true,
                     'enum' => [[1, 2], ['foo', 'bar']], ],
             ], '[1,2]', [1, 2]],
-            [(object) [
-                'format' => 'default', 'constraints' => (object) ['enum' => [[1, 2], ['foo', 'bar']]],
+            [[
+                'format' => 'default', 'constraints' => ['enum' => [[1, 2], ['foo', 'bar']]],
             ], [1, 2], [1, 2]],
             // minLength / maxLength
-            [(object) ['format' => 'default', 'constraints' => (object) ['minLength' => 1]], [], self::ERROR],
-            [(object) ['format' => 'default', 'constraints' => (object) ['minLength' => 1]], [1], [1]],
-            [(object) ['format' => 'default', 'constraints' => (object) ['minLength' => 1]], [1, 2], [1, 2]],
-            [(object) ['format' => 'default', 'constraints' => (object) ['minLength' => 1]], 'invalid', self::ERROR],
-            [(object) ['format' => 'default', 'constraints' => (object) ['maxLength' => 1]], [], []],
-            [(object) ['format' => 'default', 'constraints' => (object) ['maxLength' => 1]], [1], [1]],
-            [(object) ['format' => 'default', 'constraints' => (object) ['maxLength' => 1]], [1, 2], self::ERROR],
-            [(object) ['format' => 'default', 'constraints' => (object) ['minLength' => 1, 'maxLength' => 1]],
+            [['format' => 'default', 'constraints' => ['minLength' => 1]], [], self::ERROR],
+            [['format' => 'default', 'constraints' => ['minLength' => 1]], [1], [1]],
+            [['format' => 'default', 'constraints' => ['minLength' => 1]], [1, 2], [1, 2]],
+            [['format' => 'default', 'constraints' => ['minLength' => 1]], 'invalid', self::ERROR],
+            [['format' => 'default', 'constraints' => ['maxLength' => 1]], [], []],
+            [['format' => 'default', 'constraints' => ['maxLength' => 1]], [1], [1]],
+            [['format' => 'default', 'constraints' => ['maxLength' => 1]], [1, 2], self::ERROR],
+            [['format' => 'default', 'constraints' => ['minLength' => 1, 'maxLength' => 1]],
                 [1, 2], self::ERROR, ],
-            [(object) ['format' => 'default', 'constraints' => (object) ['minLength' => 1, 'maxLength' => 1]],
+            [['format' => 'default', 'constraints' => ['minLength' => 1, 'maxLength' => 1]],
                 [1], [1], ],
-            [(object) ['format' => 'default', 'constraints' => (object) ['minLength' => 1, 'maxLength' => 1]],
+            [['format' => 'default', 'constraints' => ['minLength' => 1, 'maxLength' => 1]],
                 [], self::ERROR, ],
         ]);
     }
@@ -91,7 +91,7 @@ public function testBoolean()
     {
         $this->assertFieldTestData('boolean', [
             ['default', true, true],
-            [(object) ['format' => 'default', 'trueValues' => ['yes']], 'yes', true],
+            [['format' => 'default', 'trueValues' => ['yes']], 'yes', true],
             ['default', 'y', self::ERROR],
             ['default', 'true', true],
             ['default', 't', self::ERROR],
@@ -102,7 +102,7 @@ public function testBoolean()
             ['default', 'no', self::ERROR],
             ['default', 'n', self::ERROR],
             ['default', 'false', false],
-            [(object) ['format' => 'default', 'falseValues' => ['f']], 'f', false],
+            [['format' => 'default', 'falseValues' => ['f']], 'f', false],
             ['default', '0', false],
             ['default', 'NO', self::ERROR],
             ['default', 'No', self::ERROR],
@@ -111,13 +111,13 @@ public function testBoolean()
             ['default', '3.14', self::ERROR],
             ['default', '', self::ERROR],  // missingValues is handled at the schema level,
             // required
-            [(object) ['format' => 'default', 'constraints' => (object) ['required' => true]], null, self::ERROR],
+            [['format' => 'default', 'constraints' => ['required' => true]], null, self::ERROR],
             // enum
-            [(object) [
-                'format' => 'default', 'constraints' => (object) ['enum' => [false]],
+            [[
+                'format' => 'default', 'constraints' => ['enum' => [false]],
             ], true, self::ERROR],
-            [(object) [
-                'format' => 'default', 'constraints' => (object) ['enum' => [false]],
+            [[
+                'format' => 'default', 'constraints' => ['enum' => [false]],
             ], false, false],
         ]);
     }
@@ -142,14 +142,19 @@ public function testDate()
             ['%d/%m/%y', '', self::ERROR],  // missingValues is handled at the schema level,
             ['invalid', '21/11/06 16:30', self::ERROR],
             // required
-            [(object) ['format' => 'default', 'constraints' => (object) ['required' => true]], null, self::ERROR],
+            [['format' => 'default', 'constraints' => ['required' => true]], null, self::ERROR],
             // enum
-            [(object) [
-                'format' => 'default', 'constraints' => (object) ['enum' => ['2019-01-01']],
+            [[
+                'format' => 'default', 'constraints' => ['enum' => ['2019-01-01']],
             ], '2019-01-01', Carbon::create(2019, 1, 1, 0, 0, 0)],
-            [(object) [
-                'format' => 'default', 'constraints' => (object) ['enum' => ['2019-01-01']],
+            [[
+                'format' => 'default', 'constraints' => ['enum' => ['2019-01-01']],
             ], '2019-01-02', self::ERROR],
+            // minimum / maximum
+            [['format' => 'default', 'constraints' => ['minimum' => '2019-01-01']], '2018-12-28', self::ERROR],
+            [['format' => 'default', 'constraints' => ['maximum' => '2019-01-01']], '2019-01-02', self::ERROR],
+            [['format' => 'default', 'constraints' => ['minimum' => '2019-01-01', 'maximum' => '2019-01-01']], '2019-01-01', Carbon::create(2019, 1, 1, 0, 0, 0)],
+            [['format' => 'default', 'constraints' => ['minimum' => '2019-01-01', 'maximum' => '2019-01-04']], '2019-01-01', Carbon::create(2019, 1, 1, 0, 0, 0)],
         ]);
     }
 
@@ -173,14 +178,19 @@ public function testDatetime()
             ['%d/%m/%y %H:%M', '', self::ERROR],  // missingValues is handled at the schema level,
             ['invalid', '21/11/06 16:30', self::ERROR],
             // required
-            [(object) ['format' => 'default', 'constraints' => (object) ['required' => true]], null, self::ERROR],
+            [['format' => 'default', 'constraints' => ['required' => true]], null, self::ERROR],
             // enum
-            [(object) [
-                'format' => 'default', 'constraints' => (object) ['enum' => ['2014-01-01T06:00:00Z']],
+            [[
+                'format' => 'default', 'constraints' => ['enum' => ['2014-01-01T06:00:00Z']],
             ], '2014-01-01T06:00:00Z', Carbon::create(2014, 1, 1, 6, 0, 0, 'UTC')],
-            [(object) [
-                'format' => 'default', 'constraints' => (object) ['enum' => ['2014-01-01T06:00:00Z']],
+            [[
+                'format' => 'default', 'constraints' => ['enum' => ['2014-01-01T06:00:00Z']],
             ], '2014-01-01T06:01:00Z', self::ERROR],
+            // minimum / maximum
+            [['format' => 'default', 'constraints' => ['minimum' => '2014-01-01T06:35:21Z']], '2014-01-01T06:35:20Z', self::ERROR],
+            [['format' => 'default', 'constraints' => ['maximum' => '2014-01-01T06:35:21Z']], '2014-01-01T06:35:22Z', self::ERROR],
+            [['format' => 'default', 'constraints' => ['minimum' => '2014-01-01T06:35:21Z', 'maximum' => '2014-01-01T06:35:21Z']], '2014-01-01T06:35:21Z', Carbon::create(2014, 1, 1, 6, 35, 21, 'UTC')],
+            [['format' => 'default', 'constraints' => ['minimum' => '2014-01-01T06:35:21Z', 'maximum' => '2014-01-01T06:35:22Z']], '2014-01-01T06:35:21Z', Carbon::create(2014, 1, 1, 6, 35, 21, 'UTC')],
         ]);
     }
 
@@ -198,15 +208,15 @@ public function testDuration()
             ['default', 1, self::ERROR],
             ['default', '', self::ERROR],  // missingValues is handled at the schema level,
             ['default', [], self::ERROR],
-            ['default', (object) [], self::ERROR],
+            ['default', [], self::ERROR],
             // required
-            [(object) ['format' => 'default', 'constraints' => (object) ['required' => true]], null, self::ERROR],
+            [['format' => 'default', 'constraints' => ['required' => true]], null, self::ERROR],
             // enum
-            [(object) [
-                'format' => 'default', 'constraints' => (object) ['enum' => ['P1Y10M3DT5H11M7S']],
+            [[
+                'format' => 'default', 'constraints' => ['enum' => ['P1Y10M3DT5H11M7S']],
             ], 'P1Y10M3DT5H11M7S', new CarbonInterval(1, 10, 0, 3, 5, 11, 7)],
-            [(object) [
-                'format' => 'default', 'constraints' => (object) ['enum' => ['P1Y10M3DT5H11M7S']],
+            [[
+                'format' => 'default', 'constraints' => ['enum' => ['P1Y10M3DT5H11M7S']],
             ], 'P1Y10M3DT5H11M8S', self::ERROR],
         ]);
     }
@@ -216,47 +226,47 @@ public function testGeojson()
         $this->assertFieldTestData('geojson', [
             [
                 'default',
-                (object) ['properties' => (object) ['Ã' => 'Ã'], 'type' => 'Feature', 'geometry' => null],
-                (object) ['properties' => (object) ['Ã' => 'Ã'], 'type' => 'Feature', 'geometry' => null],
+                ['properties' => ['Ã' => 'Ã'], 'type' => 'Feature', 'geometry' => null],
+                ['properties' => ['Ã' => 'Ã'], 'type' => 'Feature', 'geometry' => null],
             ],
             [
                 'default',
                 '{"geometry": null, "type": "Feature", "properties": {"\\u00c3": "\\u00c3"}}',
-                (object) ['properties' => (object) ['Ã' => 'Ã'], 'type' => 'Feature', 'geometry' => null],
+                ['properties' => ['Ã' => 'Ã'], 'type' => 'Feature', 'geometry' => null],
             ],
             [
                 'default',
-                (object) ['coordinates' => [0, 0, 0], 'type' => 'Point'],
-                (object) ['coordinates' => [0, 0, 0], 'type' => 'Point'],
+                ['coordinates' => [0, 0, 0], 'type' => 'Point'],
+                ['coordinates' => [0, 0, 0], 'type' => 'Point'],
             ],
             ['default', 'string', self::ERROR],
             ['default', 1, self::ERROR],
             ['default', '3.14', self::ERROR],
             ['default', '', self::ERROR],  // missingValues is handled at the schema level,
-            ['default', (object) [], self::ERROR],
+            ['default', [], self::ERROR],
             ['default', '{}', self::ERROR],
             [
                 'topojson',
-                (object) ['type' => 'LineString', 'arcs' => [42]],
-                (object) ['type' => 'LineString', 'arcs' => [42]],
+                ['type' => 'LineString', 'arcs' => [42]],
+                ['type' => 'LineString', 'arcs' => [42]],
             ],
             [
                 'topojson',
                 '{"type": "LineString", "arcs": [42]}',
-                (object) ['type' => 'LineString', 'arcs' => [42]],
+                ['type' => 'LineString', 'arcs' => [42]],
             ],
             ['topojson', 'string', self::ERROR],
             ['topojson', 1, self::ERROR],
             ['topojson', '3.14', self::ERROR],
             ['topojson', '', self::ERROR],
             // required
-            [(object) ['format' => 'default', 'constraints' => (object) ['required' => true]], null, self::ERROR],
+            [['format' => 'default', 'constraints' => ['required' => true]], null, self::ERROR],
             // enum
-            [(object) [
-                'format' => 'default', 'constraints' => (object) ['enum' => ['{"geometry": null, "type": "Feature", "properties": {"\\u00c3": "\\u00c3"}}']],
-            ], '{"geometry": null, "type": "Feature", "properties": {"\\u00c3": "\\u00c3"}}', (object) ['properties' => (object) ['Ã' => 'Ã'], 'type' => 'Feature', 'geometry' => null]],
-            [(object) [
-                'format' => 'default', 'constraints' => (object) ['enum' => ['{"geometry": null, "type": "Feature", "properties": {"\\u00c3": "\\u00c3"}}']],
+            [[
+                'format' => 'default', 'constraints' => ['enum' => ['{"geometry": null, "type": "Feature", "properties": {"\\u00c3": "\\u00c3"}}']],
+            ], '{"geometry": null, "type": "Feature", "properties": {"\\u00c3": "\\u00c3"}}', ['properties' => ['Ã' => 'Ã'], 'type' => 'Feature', 'geometry' => null]],
+            [[
+                'format' => 'default', 'constraints' => ['enum' => ['{"geometry": null, "type": "Feature", "properties": {"\\u00c3": "\\u00c3"}}']],
             ], '{"geometry": null, "type": "Feature", "properties": {"\\u00c3": "\\u00c4"}}', self::ERROR],
         ]);
     }
@@ -268,7 +278,7 @@ public function testGeopoint()
             ['default', [180, 90],  self::ERROR],
             ['default', '180,90',  [180, 90]],
             ['default', '180, -90',  [180, -90]],
-            ['default', (object) ['lon' => 180, 'lat' => 90], self::ERROR],
+            ['default', ['lon' => 180, 'lat' => 90], self::ERROR],
             ['default', '181,90', self::ERROR],
             ['default', '0,91', self::ERROR],
             ['default', 'string', self::ERROR],
@@ -278,7 +288,7 @@ public function testGeopoint()
             ['array',  [180, 90],  [180, 90]],
             ['array', [180, 90],  [180, 90]],
             ['array', '[180, -90]',  [180, -90]],
-            ['array', (object) ['lon' => 180, 'lat' => 90], self::ERROR],
+            ['array', ['lon' => 180, 'lat' => 90], self::ERROR],
             ['array', [181, 90], self::ERROR],
             ['array', [0, 91], self::ERROR],
             ['array', '180,90', self::ERROR],
@@ -286,12 +296,12 @@ public function testGeopoint()
             ['array', 1, self::ERROR],
             ['array', '3.14', self::ERROR],
             ['array', '', self::ERROR],  // missingValues is handled at the schema level,
-            ['object', (object) ['lon' => 180, 'lat' => 90],  [180, 90]],
+            ['object', ['lon' => 180, 'lat' => 90],  [180, 90]],
             ['object', '{"lon":180, "lat":90}',  [180, 90]],
             ['object', '{"lat":90, "lon":180, "foo": "bar"}',  [180, 90]],
             ['object', '[180, -90]', self::ERROR],
-            ['object', (object) ['lon' => 181, 'lat' => 90], self::ERROR],
-            ['object', (object) ['lon' => 180, 'lat' => -91], self::ERROR],
+            ['object', ['lon' => 181, 'lat' => 90], self::ERROR],
+            ['object', ['lon' => 180, 'lat' => -91], self::ERROR],
             ['object', [180, -90], self::ERROR],
             ['object', '180,90', self::ERROR],
             ['object', 'string', self::ERROR],
@@ -299,10 +309,10 @@ public function testGeopoint()
             ['object', '3.14', self::ERROR],
             ['object', '', self::ERROR],  // missingValues is handled at the schema level,
             // required
-            [(object) ['format' => 'default', 'constraints' => (object) ['required' => true]], null, self::ERROR],
+            [['format' => 'default', 'constraints' => ['required' => true]], null, self::ERROR],
             // enum
-            [(object) ['format' => 'array', 'constraints' => (object) ['enum' => ['[180, -90]']]], '[180, -90]', [180, -90]],
-            [(object) ['format' => 'array', 'constraints' => (object) ['enum' => ['[180, -90]']]], '[171, -90]', self::ERROR],
+            [['format' => 'array', 'constraints' => ['enum' => ['[180, -90]']]], '[180, -90]', [180, -90]],
+            [['format' => 'array', 'constraints' => ['enum' => ['[180, -90]']]], '[171, -90]', self::ERROR],
         ]);
     }
 
@@ -314,74 +324,97 @@ public function testInteger()
             ['default', '3.14', self::ERROR],
             ['default', '', self::ERROR],  // missingValues is handled at the schema level,
             // required
-            [(object) ['format' => 'default', 'constraints' => (object) ['required' => true]], null, self::ERROR],
+            [['format' => 'default', 'constraints' => ['required' => true]], null, self::ERROR],
             // enum
-            [(object) ['format' => 'default', 'constraints' => (object) ['enum' => [0, '1']]], '0', 0],
-            [(object) ['format' => 'default', 'constraints' => (object) ['enum' => [0, '1']]], '2', self::ERROR],
+            [['format' => 'default', 'constraints' => ['enum' => [0, '1']]], '0', 0],
+            [['format' => 'default', 'constraints' => ['enum' => [0, '1']]], '2', self::ERROR],
+            // minimum / maximum
+            [['format' => 'default', 'constraints' => ['minimum' => 2]], 1, self::ERROR],
+            [['format' => 'default', 'constraints' => ['maximum' => '0']], 1, self::ERROR],
+            [['format' => 'default', 'constraints' => ['maximum' => "1", 'minimum' => 1]], "1", 1],
         ]);
     }
 
     public function testNumber()
     {
         $this->assertFieldTestData('number', [
-            [(object) ['format' => 'default'], 1, 1.0],
-            [(object) ['format' => 'default'], 1, 1.0],
-            [(object) ['format' => 'default'], 1.0, 1.0],
-            [(object) ['format' => 'default'], '1', 1.0],
-            [(object) ['format' => 'default'], '10.00', 10.0],
-            [(object) ['format' => 'default'], '10.50', 10.5],
-            [(object) ['format' => 'default'], '100%', 1.0],
-            [(object) ['format' => 'default'], '1000‰', self::ERROR],  // spec only supports percent sign
-            [(object) ['format' => 'default'], '-1000', -1000.0],
-            [(object) ['format' => 'default', 'groupChar' => ','], '1,000', 1000.0],
-            [(object) ['format' => 'default', 'groupChar' => ','], '10,000.00', 10000.0],
-            [(object) ['format' => 'default', 'groupChar' => ','], '10,000,000.50', 10000000.5],
-            [(object) ['format' => 'default', 'groupChar' => '#'], '10#000.00', 10000.0],
-            [(object) ['format' => 'default', 'groupChar' => '#'], '10#000#000.50', 10000000.5],
-            [(object) ['format' => 'default', 'groupChar' => '#'], '10.50', 10.5],
-            [(object) ['format' => 'default', 'groupChar' => '#'], '1#000', 1000.0],
-            [(object) ['format' => 'default', 'groupChar' => '#', 'decimalChar' => '@'], '10#000@00', 10000.0],
-            [(object) ['format' => 'default', 'groupChar' => '#', 'decimalChar' => '@'], '10#000#000@50', 10000000.5],
-            [(object) ['format' => 'default', 'groupChar' => '#', 'decimalChar' => '@'], '10@50', 10.5],
-            [(object) ['format' => 'default', 'groupChar' => '#', 'decimalChar' => '@'], '1#000', 1000.0],
-            [(object) ['format' => 'default', 'groupChar' => ',', 'currency' => true], '10,000.00', 10000.0],
-            [(object) ['format' => 'default', 'groupChar' => ',', 'currency' => true], '10,000,000.00', 10000000.0],
-            [(object) ['format' => 'default', 'currency' => true], '$10000.00', 10000.0],
-            [(object) ['format' => 'default', 'groupChar' => ',', 'currency' => true], '  10,000.00 €', 10000.0],
-            [(object) ['format' => 'default', 'groupChar' => ' ', 'decimalChar' => ','], '10 000,00', 10000.0],
-            [(object) ['format' => 'default', 'groupChar' => ' ', 'decimalChar' => ','], '10 000 000,00', 10000000.0],
-            [(object) ['format' => 'default', 'groupChar' => ' ', 'decimalChar' => ',', 'currency' => true], '10000,00 ₪', 10000.0],
-            [(object) ['format' => 'default', 'groupChar' => ' ', 'decimalChar' => ',', 'currency' => true], '  10 000,00 £', 10000.0],
-            [(object) ['format' => 'default'], '10,000a.00', self::ERROR],
-            [(object) ['format' => 'default'], '10+000.00', self::ERROR],
-            [(object) ['format' => 'default'], '$10:000.00', self::ERROR],
-            [(object) ['format' => 'default'], 'string', self::ERROR],
-            [(object) ['format' => 'default'], '', self::ERROR],  // missingValues is handled at the schema level,
+            [['format' => 'default'], 1, 1.0],
+            [['format' => 'default'], 1, 1.0],
+            [['format' => 'default'], 1.0, 1.0],
+            [['format' => 'default'], '1', 1.0],
+            [['format' => 'default'], '10.00', 10.0],
+            [['format' => 'default'], '10.50', 10.5],
+            [['format' => 'default'], '100%', 1.0],
+            [['format' => 'default'], '1000‰', self::ERROR],  // spec only supports percent sign
+            [['format' => 'default'], '-1000', -1000.0],
+            [['format' => 'default', 'groupChar' => ','], '1,000', 1000.0],
+            [['format' => 'default', 'groupChar' => ','], '10,000.00', 10000.0],
+            [['format' => 'default', 'groupChar' => ','], '10,000,000.50', 10000000.5],
+            [['format' => 'default', 'groupChar' => '#'], '10#000.00', 10000.0],
+            [['format' => 'default', 'groupChar' => '#'], '10#000#000.50', 10000000.5],
+            [['format' => 'default', 'groupChar' => '#'], '10.50', 10.5],
+            [['format' => 'default', 'groupChar' => '#'], '1#000', 1000.0],
+            [['format' => 'default', 'groupChar' => '#', 'decimalChar' => '@'], '10#000@00', 10000.0],
+            [['format' => 'default', 'groupChar' => '#', 'decimalChar' => '@'], '10#000#000@50', 10000000.5],
+            [['format' => 'default', 'groupChar' => '#', 'decimalChar' => '@'], '10@50', 10.5],
+            [['format' => 'default', 'groupChar' => '#', 'decimalChar' => '@'], '1#000', 1000.0],
+            [['format' => 'default', 'groupChar' => ',', 'currency' => true], '10,000.00', 10000.0],
+            [['format' => 'default', 'groupChar' => ',', 'currency' => true], '10,000,000.00', 10000000.0],
+            [['format' => 'default', 'currency' => true], '$10000.00', 10000.0],
+            [['format' => 'default', 'groupChar' => ',', 'currency' => true], '  10,000.00 €', 10000.0],
+            [['format' => 'default', 'groupChar' => ' ', 'decimalChar' => ','], '10 000,00', 10000.0],
+            [['format' => 'default', 'groupChar' => ' ', 'decimalChar' => ','], '10 000 000,00', 10000000.0],
+            [['format' => 'default', 'groupChar' => ' ', 'decimalChar' => ',', 'currency' => true], '10000,00 ₪', 10000.0],
+            [['format' => 'default', 'groupChar' => ' ', 'decimalChar' => ',', 'currency' => true], '  10 000,00 £', 10000.0],
+            [['format' => 'default'], '10,000a.00', self::ERROR],
+            [['format' => 'default'], '10+000.00', self::ERROR],
+            [['format' => 'default'], '$10:000.00', self::ERROR],
+            [['format' => 'default'], 'string', self::ERROR],
+            [['format' => 'default'], '', self::ERROR],  // missingValues is handled at the schema level,
             // required
-            [(object) ['format' => 'default', 'constraints' => (object) ['required' => true]], null, self::ERROR],
+            [['format' => 'default', 'constraints' => ['required' => true]], null, self::ERROR],
             // enum
-            [(object) ['format' => 'default', 'constraints' => (object) ['enum' => [0.5, '1.6']]], '1.6', 1.6],
-            [(object) ['format' => 'default', 'constraints' => (object) ['enum' => [0.5, '1.6']]], '0.55', self::ERROR],
+            [['format' => 'default', 'constraints' => ['enum' => [0.5, '1.6']]], '1.6', 1.6],
+            [['format' => 'default', 'constraints' => ['enum' => [0.5, '1.6']]], '0.55', self::ERROR],
+            // minimum / maximum
+            [['format' => 'default', 'constraints' => ['minimum' => 2]], 1.4, self::ERROR],
+            [['format' => 'default', 'constraints' => ['maximum' => '0']], 1.2, self::ERROR],
+            [['format' => 'default', 'constraints' => ['minimum' => 1.1, 'maximum' => "1.1"]], "1.1", 1.1],
+            [['format' => 'default', 'constraints' => ['minimum' => 1.2, 'maximum' => "1.4"]], "1.2", 1.2],
         ]);
     }
 
     public function testObject()
     {
         $this->assertFieldTestData('object', [
-            ['default', (object) [], (object) []],
-            ['default', '{}', (object) []],
-            ['default', (object) ['key' => 'value'], (object) ['key' => 'value']],
-            ['default', '{"key": "value"}', (object) ['key' => 'value']],
+            ['default', [], []],
+            ['default', '{}', []],
+            ['default', ['key' => 'value'], ['key' => 'value']],
+            ['default', '{"key": "value"}', ['key' => 'value']],
             ['default', '["key", "value"]', self::ERROR],
             ['default', 'string', self::ERROR],
             ['default', 1, self::ERROR],
             ['default', '3.14', self::ERROR],
             ['default', '', self::ERROR],  // missingValues is handled at the schema level,
             // required
-            [(object) ['format' => 'default', 'constraints' => (object) ['required' => true]], null, self::ERROR],
+            [['format' => 'default', 'constraints' => ['required' => true]], null, self::ERROR],
             // enum
-            [(object) ['format' => 'default', 'constraints' => (object) ['enum' => ['{"foo":"bar"}']]], '{"foo":"bar"}', (object) ['foo' => 'bar']],
-            [(object) ['format' => 'default', 'constraints' => (object) ['enum' => ['{"foo":"bar"}']]], '{"foox":"bar"}', self::ERROR],
+            [['format' => 'default', 'constraints' => ['enum' => ['{"foo":"bar"}']]], '{"foo":"bar"}', ['foo' => 'bar']],
+            [['format' => 'default', 'constraints' => ['enum' => ['{"foo":"bar"}']]], '{"foox":"bar"}', self::ERROR],
+            // minLength / maxLength
+            [['format' => 'default', 'constraints' => ['minLength' => 1]], '{}', self::ERROR],
+            [['format' => 'default', 'constraints' => ['minLength' => 1]], '{"a":1}', (object)["a"=>1]],
+            [['format' => 'default', 'constraints' => ['minLength' => 1]], '{"a":1, "b":2}', (object)["a"=>1,"b"=>2]],
+            [['format' => 'default', 'constraints' => ['minLength' => 1]], 'invalid', self::ERROR],
+            [['format' => 'default', 'constraints' => ['maxLength' => 1]], '{}', (object)[]],
+            [['format' => 'default', 'constraints' => ['maxLength' => 1]], '{"a":1}', (object)["a"=>1]],
+            [['format' => 'default', 'constraints' => ['maxLength' => 1]], '{"a":1, "b":2}', self::ERROR],
+            [['format' => 'default', 'constraints' => ['minLength' => 1, 'maxLength' => 1]],
+                '{"a":1, "b":2}', self::ERROR, ],
+            [['format' => 'default', 'constraints' => ['minLength' => 1, 'maxLength' => 1]],
+                '{"a":1}', (object)["a"=>1], ],
+            [['format' => 'default', 'constraints' => ['minLength' => 1, 'maxLength' => 1]],
+                '{}', self::ERROR, ],
         ]);
     }
 
@@ -404,11 +437,27 @@ public function testString()
             ['binary', 'dGVzdA==', 'dGVzdA=='],
             ['binary', '', ''],
             // required
-            [(object) ['format' => 'default', 'constraints' => (object) ['required' => true]], '', ''],
-            [(object) ['format' => 'default', 'constraints' => (object) ['required' => true]], null, self::ERROR],
+            [['format' => 'default', 'constraints' => ['required' => true]], '', ''],
+            [['format' => 'default', 'constraints' => ['required' => true]], null, self::ERROR],
             // enum
-            [(object) ['format' => 'default', 'constraints' => (object) ['enum' => ['foobar']]], 'foobar', 'foobar'],
-            [(object) ['format' => 'default', 'constraints' => (object) ['enum' => ['foobar']]], 'foobarx', self::ERROR],
+            [['format' => 'default', 'constraints' => ['enum' => ['foobar']]], 'foobar', 'foobar'],
+            [['format' => 'default', 'constraints' => ['enum' => ['foobar']]], 'foobarx', self::ERROR],
+            // minLength / maxLength
+            [['format' => 'default', 'constraints' => ['minLength' => 1]], "", self::ERROR],
+            [['format' => 'default', 'constraints' => ['minLength' => 1]], "a", "a"],
+            [['format' => 'default', 'constraints' => ['minLength' => 1]], "ab", "ab"],
+            [['format' => 'default', 'constraints' => ['maxLength' => 1]], "", ""],
+            [['format' => 'default', 'constraints' => ['maxLength' => 1]], "a", "a"],
+            [['format' => 'default', 'constraints' => ['maxLength' => 1]], "ab", self::ERROR],
+            [['format' => 'default', 'constraints' => ['minLength' => 1, 'maxLength' => 1]],
+                "ab", self::ERROR, ],
+            [['format' => 'default', 'constraints' => ['minLength' => 1, 'maxLength' => 1]],
+                "a", "a", ],
+            [['format' => 'default', 'constraints' => ['minLength' => 1, 'maxLength' => 1]],
+                "", self::ERROR, ],
+            // pattern
+            [['format' => 'default', 'constraints' => ['pattern' => '^[a-z]*$']], 'AAA', self::ERROR],
+            [['format' => 'default', 'constraints' => ['pattern' => '^[a-z]*$']], 'aaa', 'aaa']
         ]);
     }
 
@@ -442,10 +491,15 @@ public function testTime()
             ['%H:%M:%S', '06:35:21', [6, 35, 21]],
             ['%H:%M', '06:35:21', self::ERROR],
             // required
-            [(object) ['format' => 'default', 'constraints' => (object) ['required' => true]], null, self::ERROR],
+            [['format' => 'default', 'constraints' => ['required' => true]], null, self::ERROR],
             // enum
-            [(object) ['format' => 'default', 'constraints' => (object) ['enum' => ['06:00:00']]], '06:00:00', [6, 0, 0]],
-            [(object) ['format' => 'default', 'constraints' => (object) ['enum' => ['06:00:00']]], '06:01:00', self::ERROR],
+            [['format' => 'default', 'constraints' => ['enum' => ['06:00:00']]], '06:00:00', [6, 0, 0]],
+            [['format' => 'default', 'constraints' => ['enum' => ['06:00:00']]], '06:01:00', self::ERROR],
+            // minimum / maximum
+            [['format' => 'default', 'constraints' => ['minimum' => '06:35:21']], '06:35:20', self::ERROR],
+            [['format' => 'default', 'constraints' => ['maximum' => '06:35:21']], '06:35:22', self::ERROR],
+            [['format' => 'default', 'constraints' => ['minimum' => '06:35:21', 'maximum' => '06:35:21']], '06:35:21', [6, 35, 21]],
+            [['format' => 'default', 'constraints' => ['minimum' => '06:35:21', 'maximum' => '06:35:22']], '06:35:21', [6, 35, 21]],
         ]);
     }
 
@@ -458,10 +512,14 @@ public function testYear()
             ['default', 20000, 20000],
             ['default', '3.14', self::ERROR],
             // required
-            [(object) ['format' => 'default', 'constraints' => (object) ['required' => true]], null, self::ERROR],
+            [['format' => 'default', 'constraints' => ['required' => true]], null, self::ERROR],
             // enum
-            [(object) ['format' => 'default', 'constraints' => (object) ['enum' => [2000]]], '2000', 2000],
-            [(object) ['format' => 'default', 'constraints' => (object) ['enum' => [2000]]], '2001', self::ERROR],
+            [['format' => 'default', 'constraints' => ['enum' => [2000]]], '2000', 2000],
+            [['format' => 'default', 'constraints' => ['enum' => [2000]]], '2001', self::ERROR],
+            // minimum / maximum
+            [['format' => 'default', 'constraints' => ['minimum' => '2000']], '1999', self::ERROR],
+            [['format' => 'default', 'constraints' => ['maximum' => '2000']], '2001', self::ERROR],
+            [['format' => 'default', 'constraints' => ['minimum' => '2000', 'maximum' => '2000']], '2000', 2000],
         ]);
     }
 
@@ -482,10 +540,15 @@ public function testYearMonth()
             ['default', '3.14', self::ERROR],
             ['default', '', self::ERROR],
             // required
-            [(object) ['format' => 'default', 'constraints' => (object) ['required' => true]], null, self::ERROR],
+            [['format' => 'default', 'constraints' => ['required' => true]], null, self::ERROR],
             // enum
-            [(object) ['format' => 'default', 'constraints' => (object) ['enum' => [[2000, 10]]]], '2000-10', [2000, 10]],
-            [(object) ['format' => 'default', 'constraints' => (object) ['enum' => [[2000, 10]]]], '2000-11', self::ERROR],
+            [['format' => 'default', 'constraints' => ['enum' => [[2000, 10]]]], '2000-10', [2000, 10]],
+            [['format' => 'default', 'constraints' => ['enum' => [[2000, 10]]]], '2000-10', [2000, 10]],
+            [['format' => 'default', 'constraints' => ['enum' => [[2000, 10]]]], '2000-11', self::ERROR],
+            // minimum / maximum
+            [['format' => 'default', 'constraints' => ['minimum' => '2000-10']], '1999-12', self::ERROR],
+            [['format' => 'default', 'constraints' => ['maximum' => '2000-10']], '2001-01', self::ERROR],
+            [['format' => 'default', 'constraints' => ['minimum' => '2000-10', 'maximum' => '2000-10']], '2000-10', [2000, 10]],
         ]);
     }
 
@@ -496,15 +559,15 @@ protected function assertFieldTestData($fieldType, $testData)
                 $testLine[3] = null;
             }
             list($format, $inputValue, $expectedCastValue, $expectedInferType) = $testLine;
-            if (is_object($format)) {
+            if (is_array($format)) {
                 $descriptor = $format;
-                $descriptor->type = $fieldType;
+                $descriptor["type"] = $fieldType;
             } else {
-                $descriptor = (object) ['type' => $fieldType, 'format' => $format];
+                $descriptor = ['type' => $fieldType, 'format' => $format];
             }
             $assertMessage = 'descriptor='.json_encode($descriptor).", input='".json_encode($inputValue)."', expected='".json_encode($expectedCastValue)."'";
-            if (!isset($descriptor->name)) {
-                $descriptor->name = 'unknown';
+            if (!isset($descriptor["name"])) {
+                $descriptor["name"] = 'unknown';
             }
             $field = FieldsFactory::field($descriptor);
             if ($expectedCastValue === self::ERROR) {