Null safety

Author: martijn00

lib/src/base_validator.dart

@@ -22,10 +22,15 @@ abstract class BaseValidator<T> {
 
   /// Validates the value and checks if it is null or empty.
   String? validate(T? valueCandidate) {
-    if (checkNullOrEmpty && isNullOrEmpty(valueCandidate)) {
+    final bool isNullOrEmpty = this.isNullOrEmpty(valueCandidate);
+
+    if (checkNullOrEmpty && isNullOrEmpty) {
       return errorText;
+    } else if (!checkNullOrEmpty && isNullOrEmpty) {
+      return null;
+    } else {
+      return validateValue(valueCandidate as T);
     }
-    return validateValue(valueCandidate);
   }
 
   /// Checks if the value is null or empty.
@@ -43,5 +48,5 @@ abstract class BaseValidator<T> {
 
   /// Validates the value.
   /// Returns `null` if the value is valid, otherwise an error message.
-  String? validateValue(T? valueCandidate);
+  String? validateValue(T valueCandidate);
 }

lib/src/bool/has_lowercase_chars_validator.dart

@@ -34,8 +34,8 @@ class HasLowercaseCharsValidator extends BaseValidator<String> {
   static final RegExp _lowerCase = RegExp('[^a-zñ]');
 
   @override
-  String? validateValue(String? valueCandidate) {
-    return lowercaseCharLength(valueCandidate!) >= atLeast ? null : errorText;
+  String? validateValue(String valueCandidate) {
+    return lowercaseCharLength(valueCandidate) >= atLeast ? null : errorText;
   }
 
   int lowercaseCharLength(String value) {

lib/src/bool/has_numeric_chars_validator.dart

@@ -34,8 +34,8 @@ class HasNumericCharsValidator extends BaseValidator<String> {
   static final RegExp _number = RegExp('[^0-9]');
 
   @override
-  String? validateValue(String? valueCandidate) {
-    return numberCharLength(valueCandidate!) >= atLeast ? null : errorText;
+  String? validateValue(String valueCandidate) {
+    return numberCharLength(valueCandidate) >= atLeast ? null : errorText;
   }
 
   int numberCharLength(String value) {

lib/src/bool/has_special_chars_validator.dart

@@ -34,8 +34,8 @@ class HasSpecialCharsValidator extends BaseValidator<String> {
   static final RegExp _specialChar = RegExp('[A-Za-z0-9]');
 
   @override
-  String? validateValue(String? valueCandidate) {
-    return specialCharLength(valueCandidate!) >= atLeast ? null : errorText;
+  String? validateValue(String valueCandidate) {
+    return specialCharLength(valueCandidate) >= atLeast ? null : errorText;
   }
 
   int specialCharLength(String value) {

lib/src/bool/has_uppercase_chars_validator.dart

@@ -34,8 +34,8 @@ class HasUppercaseCharsValidator extends BaseValidator<String> {
   static final RegExp _upperCase = RegExp('[^A-ZÑ]');
 
   @override
-  String? validateValue(String? valueCandidate) {
-    return uppercaseCharLength(valueCandidate!) >= 1 ? null : errorText;
+  String? validateValue(String valueCandidate) {
+    return uppercaseCharLength(valueCandidate) >= 1 ? null : errorText;
   }
 
   int uppercaseCharLength(String value) {

lib/src/bool/is_false_validator.dart

@@ -15,7 +15,7 @@ class IsFalseValidator extends BaseValidator<bool> {
       FormBuilderLocalizations.current.mustBeFalseErrorText;
 
   @override
-  String? validateValue(bool? valueCandidate) {
-    return valueCandidate ?? false ? null : errorText;
+  String? validateValue(bool valueCandidate) {
+    return valueCandidate == false ? null : errorText;
   }
 }

lib/src/bool/is_true_validator.dart

@@ -15,7 +15,7 @@ class IsTrueValidator extends BaseValidator<bool> {
       FormBuilderLocalizations.current.mustBeTrueErrorText;
 
   @override
-  String? validateValue(bool? valueCandidate) {
-    return valueCandidate ?? true ? null : errorText;
+  String? validateValue(bool valueCandidate) {
+    return valueCandidate == true ? null : errorText;
   }
 }

lib/src/collection/contains_element_validator.dart

@@ -18,7 +18,7 @@ class ContainsElementValidator<T> extends BaseValidator<T> {
       FormBuilderLocalizations.current.containsElementErrorText;
 
   @override
-  String? validateValue(T? valueCandidate) {
+  String? validateValue(T valueCandidate) {
     return values.contains(valueCandidate) ? null : errorText;
   }
 }

lib/src/collection/equal_length_validator.dart

@@ -22,7 +22,7 @@ class EqualLengthValidator<T> extends BaseValidator<T> {
       FormBuilderLocalizations.current.equalLengthErrorText(length);
 
   @override
-  String? validateValue(T? valueCandidate) {
+  String? validateValue(T valueCandidate) {
     int valueLength = 0;
 
     if (valueCandidate is String) valueLength = valueCandidate.length;

lib/src/collection/max_length_validator.dart

@@ -18,7 +18,7 @@ class MaxLengthValidator<T> extends BaseValidator<T> {
       FormBuilderLocalizations.current.equalLengthErrorText(maxLength);
 
   @override
-  String? validateValue(T? valueCandidate) {
+  String? validateValue(T valueCandidate) {
     int valueLength = 0;
 
     if (valueCandidate is String) valueLength = valueCandidate.length;