Add lowercase rule

Author: Armnajafi

src/Validator.ts

@@ -20,6 +20,7 @@ import { RequiredWithoutRule } from './rules/RequiredWithoutRule';
 import { RequiredWithAllRule } from './rules/RequiredWithAllRule';
 import { RequiredWithoutAllRule } from './rules/RequiredWithoutAllRule';
 import { UppercaseRule } from './rules/UppercaseRule';
+import { LowercaseRule } from './rules/LowercaseRule';
 
 
 export class Validator {
@@ -42,7 +43,8 @@ export class Validator {
     required_without: new RequiredWithoutRule(),
     required_with_all: new RequiredWithAllRule(),
     required_without_all: new RequiredWithoutAllRule(),
-    uppercase: new UppercaseRule()
+    uppercase: new UppercaseRule(),
+    lowercase: new LowercaseRule()
   };
 
   constructor(private locale: string = 'en') {}

src/locales/en.json

@@ -14,5 +14,6 @@
     "required_without": "The {field} field is required when {other} is not present.",
     "required_with_all": "The {field} field is required when all of {other} are present.",
     "required_without_all": "The {field} field is required when none of {other} are present.",
-    "uppercase": "The {field} field must be uppercase."
+    "uppercase": "The {field} field must be uppercase.",
+    "lowercase": "The {field} field must be lowercase."
 }

src/locales/fa.json

@@ -8,6 +8,7 @@
     "required_without": "فیلد {field} هنگامی که {other} موجود نباشد، الزامی است.",
     "required_with_all": "فیلد {field} هنگامی که تمام فیلدهای {other} موجود باشند، الزامی است.",
     "required_without_all": "فیلد {field} هنگامی که هیچ یک از فیلدهای {other} موجود نباشند، الزامی است.",
-    "uppercase": "فیلد {field} باید با حروف بزرگ باشد."
+    "uppercase": "فیلد {field} باید با حروف بزرگ باشد.",
+    "lowercase": "فیلد {field} باید با حروف کوچک باشد."
 }
 

src/rules/LowercaseRule.ts

@@ -0,0 +1,34 @@
+import { ValidationRule } from './ValidationRule';
+
+export class LowercaseRule implements ValidationRule {
+  private defaultMessage = '';
+  private customMessage?: string;
+  
+  setDefaultMessage(message: string) {
+    this.defaultMessage = message;
+  }
+  
+  setCustomMessage(message: string) {
+    this.customMessage = message;
+  }
+  
+  validate(value: any, ruleValue: any, field: string, inputs: Record<string, any>): string | null {
+    // Skip validation if value is empty
+    if (value === undefined || value === null || value === '') {
+      return null;
+    }
+    
+    // Convert value to string if it's not already
+    const stringValue = String(value);
+    
+    // Check if the string is lowercase
+    // A string is lowercase if it's equal to its lowercase version
+    // and not equal to its uppercase version (to ensure it has at least one character)
+    if (stringValue !== stringValue.toLowerCase() || stringValue === stringValue.toUpperCase()) {
+      const msg = this.customMessage || this.defaultMessage;
+      return msg.replace('{field}', field);
+    }
+    
+    return null;
+  }
+}