From 5e583b02c5dedffb095d916ef01db8a3661bee5e Mon Sep 17 00:00:00 2001
From: Francois Best <github@francoisbest.com>
Date: Mon, 8 Jan 2024 23:59:23 +0100
Subject: [PATCH] feat: Add validation support (Zod & others)

---
 packages/nuqs/src/parsers.ts | 35 ++++++++++++++++++++++++++++++++++-
 1 file changed, 34 insertions(+), 1 deletion(-)

diff --git a/packages/nuqs/src/parsers.ts b/packages/nuqs/src/parsers.ts
index 98b68dae5..409c7cbca 100644
--- a/packages/nuqs/src/parsers.ts
+++ b/packages/nuqs/src/parsers.ts
@@ -17,6 +17,27 @@ export type ParserBuilder<T> = Required<Parser<T>> &
      */
     withOptions<This, Shallow>(this: This, options: Options<Shallow>): This
 
+    /**
+     * Pass in a validation function to perform runtime checks on the parsed
+     * value. If the validation fails, the value will be set to `null` (or
+     * the default value if specified).
+     *
+     * Validation must be synchronous, and must throw an error on invalid
+     * inputs.
+     *
+     * Example with Zod:
+     * ```ts
+     * const [posInt, setPosInt] = useQueryState(
+     *  'value',
+     *  parseAsInteger.withValidation(z.number().positive().parse)
+     * )
+     * ```
+     *
+     * @param this
+     * @param validate
+     */
+    withValidation<This>(this: This, validate: (input: unknown) => T): This
+
     /**
      * Specifying a default value makes the hook state non-nullable when the
      * query is missing from the URL.
@@ -93,6 +114,18 @@ export function createParser<T>(parser: Required<Parser<T>>): ParserBuilder<T> {
   return {
     ...parser,
     parseServerSide: parseServerSideNullable,
+    withValidation(validate) {
+      return {
+        ...this,
+        parse: (value: string) => {
+          const parsed = parser.parse(value)
+          if (parsed === null) {
+            return null
+          }
+          return validate(parsed)
+        }
+      }
+    },
     withDefault(defaultValue) {
       return {
         ...this,
@@ -102,7 +135,7 @@ export function createParser<T>(parser: Required<Parser<T>>): ParserBuilder<T> {
         }
       }
     },
-    withOptions(options: Options) {
+    withOptions(options) {
       return {
         ...this,
         ...options