feat: add vat number validation and error message support

content/docs/guides/helpers.md

@@ -156,6 +156,7 @@ Alongside the VineJS helpers, you may also use the `vine.helpers` object to acce
 - `isLatLong`
 - `isMobilePhone`
 - `isPassportNumber`
+- `isVAT`
 - `isPostalCode`
 - `isSlug`
 - `isDecimal`

content/docs/types/string.md

@@ -65,6 +65,7 @@ const messages = {
   mobile: 'The {{ field }} field must be a valid mobile phone number',
   passport: 'The {{ field }} field must be a valid passport number',
   postalCode: 'The {{ field }} field must be a valid postal code',
+  vat: 'The {{ field }} field must be a valid VAT number',
 }
 
 vine.messagesProvider = new SimpleMessagesProvider(messages)
@@ -561,6 +562,31 @@ vine.object({
 })
 ```
 
+### vat
+Ensure the field's value is formatted as a valid VAT number for a given or multiple country codes.
+
+```ts
+vine.object({
+  vat_number: vine
+    .string()
+    .vat({ countryCode: ['IN'] })
+})
+```
+
+You may define a callback function to compute the options at runtime.
+
+```ts
+vine.object({
+  vat_number: vine
+    .string()
+    .vat((field) => {
+      return {
+        countryCode: [field.parent.country_code]
+      }
+    })
+})
+```
+
 ## Mutations
 
 Following is the list of mutations you can apply to a string value.  As the name suggests, mutations normalize or change the input value and do not perform any validations.