Document for Rule::requireIf

validation.md

@@ -936,6 +936,20 @@ The field under validation must be present in the input data and not empty. A fi
 
 The field under validation must be present and not empty if the _anotherfield_ field is equal to any _value_.
 
+If you want to require the field with a custom condition, you can use the `Rule::requiredIf` method to construct the rule:
+
+    use Illuminate\Validation\Rule;
+
+    Validator::make($request->all(), [
+        'role_id' => Rule::requiredIf($request->user()->is_admin),
+    ]);
+
+    Validator::make($request->all(), [
+        'role_id' => Rule::requiredIf(function () use ($request) {
+            return $request->user()->is_admin && $some_other_complicated_condition;
+        }),
+    ]);
+
 <a name="rule-required-unless"></a>
 #### required_unless:_anotherfield_,_value_,...