Add or

Author: martijn00

README.md

@@ -50,6 +50,7 @@ Available built-in helper validators:
 
 - `FormBuilderValidators.compose()` - runs each validator against the value provided.
 - `FormBuilderValidators.conditional()` - conditionally runs a validator against the value provided.
+- `FormBuilderValidators.or()` - runs each validator against the value provided and passes when any works.
 
 Available built-in type validators include:
 

lib/src/form_builder_validators.dart

@@ -23,6 +23,26 @@ class FormBuilderValidators {
     };
   }
 
+  /// [FormFieldValidator] that is composed of other [FormFieldValidator]s.
+  /// Each validator is run against the [FormField] value and if any returns a
+  /// null result validation passes
+  static FormFieldValidator<T> or<T>(
+    List<FormFieldValidator<T>> validators,
+  ) {
+    return (valueCandidate) {
+      String? errorResult;
+      for (final validator in validators) {
+        final validatorResult = validator.call(valueCandidate);
+        if (validatorResult == null) {
+          return null;
+        } else {
+          errorResult = validatorResult;
+        }
+      }
+      return errorResult;
+    };
+  }
+
   /// [FormFieldValidator] that requires the field have a non-empty value.
   static FormFieldValidator<T> required<T>({
     String? errorText,

test/form_builder_validators_test.dart

@@ -965,4 +965,19 @@ void main() {
       expect(validator(4), isNotNull);
     }),
   );
+
+  testWidgets(
+    'FormBuilderValidators.or',
+    (WidgetTester tester) => testValidations(tester, (context) {
+      final validator = FormBuilderValidators.or([
+        FormBuilderValidators.numeric(),
+        FormBuilderValidators.startsWith(prefix: 'Hello'),
+      ]);
+      // Pass
+      expect(validator('123'), isNull);
+      expect(validator('Hello world'), isNull);
+      // Fail
+      expect(validator('123 hello'), isNotNull);
+    }),
+  );
 }