[11.x] Add RequiredIfDeclined validation rule

src/Illuminate/Validation/Concerns/ReplacesAttributes.php

@@ -609,6 +609,22 @@ protected function replaceRequiredIfAccepted($message, $attribute, $rule, $param
         return str_replace([':other'], $parameters, $message);
     }
 
+    /**
+     * Replace all place-holders for the required_if_declined rule.
+     *
+     * @param  string  $message
+     * @param  string  $attribute
+     * @param  string  $rule
+     * @param  array<int,string>  $parameters
+     * @return string
+     */
+    public function replaceRequiredIfDeclined($message, $attribute, $rule, $parameters)
+    {
+        $parameters[0] = $this->getDisplayableAttribute($parameters[0]);
+
+        return str_replace([':other'], $parameters, $message);
+    }
+
     /**
      * Replace all place-holders for the required_unless rule.
      *

src/Illuminate/Validation/Concerns/ValidatesAttributes.php

@@ -1961,6 +1961,25 @@ public function validateRequiredIfAccepted($attribute, $value, $parameters)
         return true;
     }
 
+    /**
+     * Validate that an attribute exists when another attribute was "declined".
+     *
+     * @param  string  $attribute
+     * @param  mixed  $value
+     * @param  mixed  $parameters
+     * @return bool
+     */
+    public function validateRequiredIfDeclined($attribute, $value, $parameters)
+    {
+        $this->requireParameterCount(1, $parameters, 'required_if_declined');
+
+        if ($this->validateDeclined($parameters[0], $this->getValue($parameters[0]))) {
+            return $this->validateRequired($attribute, $value);
+        }
+
+        return true;
+    }
+
     /**
      * Validate that an attribute does not exist or is an empty string.
      *

src/Illuminate/Validation/Validator.php

@@ -221,6 +221,7 @@ class Validator implements ValidatorContract
         'Required',
         'RequiredIf',
         'RequiredIfAccepted',
+        'RequiredIfDeclined',
         'RequiredUnless',
         'RequiredWith',
         'RequiredWithAll',
@@ -252,6 +253,7 @@ class Validator implements ValidatorContract
         'DeclinedIf',
         'RequiredIf',
         'RequiredIfAccepted',
+        'RequiredIfDeclined',
         'RequiredUnless',
         'RequiredWith',
         'RequiredWithAll',

tests/Validation/ValidationValidatorTest.php

@@ -2447,6 +2447,22 @@ public function testValidateAcceptedIf()
         $this->assertSame('The foo field must be accepted when bar is true.', $v->messages()->first('foo'));
     }
 
+    public function testValidateRequiredIfDeclined()
+    {
+        $trans = $this->getIlluminateArrayTranslator();
+        $v = new Validator($trans, ['foo' => 'yes', 'bar' => 'baz'], ['bar' => 'required_if_declined:foo']);
+        $this->assertTrue($v->passes());
+
+        $v = new Validator($trans, ['foo' => 'no', 'bar' => 'baz'], ['bar' => 'required_if_declined:foo']);
+        $this->assertTrue($v->passes());
+
+        $v = new Validator($trans, ['foo' => 'yes', 'bar' => ''], ['bar' => 'required_if_declined:foo']);
+        $this->assertTrue($v->passes());
+
+        $v = new Validator($trans, ['foo' => 'no', 'bar' => ''], ['bar' => 'required_if_declined:foo']);
+        $this->assertFalse($v->passes());
+    }
+
     public function testValidateDeclined()
     {
         $trans = $this->getIlluminateArrayTranslator();