darto-validate-request

Validate a request in Darto

Validation in Darto is a route middleware, zValidator, from the darto_validator package. It validates one part of the request against a zard schema (Zod-style). When validation passes, the handler runs and reads the parsed data via c.req.valid(...). When it fails, the request is rejected before the handler runs.

Setup

# pubspec.yaml
dependencies:
  darto: ^1.2.0
  darto_validator: ^1.0.0   # re-exports `zard`; no separate zard dependency

import 'package:darto/darto.dart';
import 'package:darto_validator/darto_validator.dart'; // gives you z.* and zValidator

Procedure

1. Define a schema with z:

   final userSchema = z.map({
     'name':  z.string().min(1),
     'email': z.string().email(),
     'age':   z.int().min(0).max(150),
   });
   

2. Attach zValidator(target, schema) as route middleware. The handler runs only if validation succeeds:

   app.post('/users', [zValidator('json', userSchema)], (Context c) {
     final data = c.req.valid<Map<String, dynamic>>('json');
     return c.created({'user': data});
   });
   

3. Read the validated data in the handler with the same target string: c.req.valid<Map<String, dynamic>>('json' | 'query' | 'param' | 'header'). Use the validated value — not the raw c.req.json() — so you get the parsed / coerced result.

Targets

target	Validates
'json'	JSON request body
'query'	query-string parameters
'param'	path parameters
'header'	request headers

// Query
app.get('/search', [zValidator('query', z.map({'q': z.string().min(1)}))], (c) {
  final q = c.req.valid<Map<String, dynamic>>('query');
  return c.ok({'query': q['q']});
});

// Path param
app.get('/posts/:id', [zValidator('param', z.map({'id': z.string()}))], (c) {
  final params = c.req.valid<Map<String, dynamic>>('param');
  return c.ok({'id': params['id']});
});