Additional validation logic to prevent duplicate invoices have a payment schedule assigned

app/Http/Requests/TaskScheduler/StoreSchedulerRequest.php

@@ -14,6 +14,7 @@ namespace App\Http\Requests\TaskScheduler;
 
 use App\Http\Requests\Request;
 use App\Http\ValidationRules\Scheduler\ValidClientIds;
+use App\Http\ValidationRules\Scheduler\InvoiceWithNoExistingSchedule;
 
 class StoreSchedulerRequest extends Request
 {
@@ -72,7 +73,7 @@ class StoreSchedulerRequest extends Request
             'parameters.status' => ['bail','sometimes', 'nullable', 'string'],
             'parameters.include_project_tasks' => ['bail','sometimes', 'boolean', 'required_if:template,invoice_outstanding_tasks'],
             'parameters.auto_send' => ['bail','sometimes', 'boolean', 'required_if:template,invoice_outstanding_tasks'],
-            'parameters.invoice_id' => ['bail', 'string', 'required_if:template,payment_schedule'],
+            'parameters.invoice_id' => ['bail', 'string', 'required_if:template,payment_schedule', new InvoiceWithNoExistingSchedule()],
             'parameters.auto_bill' => ['bail', 'boolean', 'required_if:template,payment_schedule'],
             'parameters.schedule' => ['bail', 'array', 'required_if:template,payment_schedule', 'min:1'],
             'parameters.schedule.*.id' => ['bail','sometimes', 'integer'],

app/Http/ValidationRules/Scheduler/InvoiceWithNoExistingSchedule.php

@@ -0,0 +1,50 @@
+<?php
+
+/**
+ * Invoice Ninja (https://invoiceninja.com).
+ *
+ * @link https://github.com/invoiceninja/invoiceninja source repository
+ *
+ * @copyright Copyright (c) 2025. Invoice Ninja LLC (https://invoiceninja.com)
+ *
+ * @license https://www.elastic.co/licensing/elastic-license
+ */
+
+namespace App\Http\ValidationRules\Scheduler;
+
+use App\Models\Client;
+use App\Utils\Traits\MakesHash;
+use App\Models\Scheduler;
+use Illuminate\Contracts\Validation\Rule;
+
+/**
+ * Class InvoiceWithNoExistingSchedule.
+ */
+class InvoiceWithNoExistingSchedule implements Rule
+{
+    use MakesHash;
+    /**
+     * @param string $attribute
+     * @param mixed $value
+     * @return bool
+     */
+    public function passes($attribute, $value)
+    {
+        /** @var \App\Models\User $user */
+        $user = auth()->user();
+
+        return Scheduler::where('company_id', $user->company()->id)
+                            ->where('template', 'payment_schedule')
+                            ->where('parameters->invoice_id', $value)
+                            ->count() == 0;        
+        
+    }
+
+    /**
+     * @return string
+     */
+    public function message()
+    {
+        return 'Invoice already has a payment schedule';
+    }
+}

tests/Feature/Scheduler/SchedulerTest.php

@@ -64,7 +64,86 @@ class SchedulerTest extends TestCase
     }
 
 
-public function testPaymentScheduleWithPercentageBasedScheduleAndFailingValidation()
+    public function testDuplicateInvoicePaymentSchedule()
+    {
+        $invoice = Invoice::factory()->create([
+            'company_id' => $this->company->id,
+            'user_id' => $this->user->id,
+            'client_id' => $this->client->id,
+            'date' => now()->format('Y-m-d'),
+            'due_date' => now()->addDays(30)->format('Y-m-d'),
+            'amount' => 300.00,
+            'balance' => 300.00,
+        ]);
+
+        $invoice->service()->markSent()->save();
+        
+        $data = [
+           'name' => 'A test payment schedule scheduler',
+           'frequency_id' => 0,
+           'next_run' => now()->format('Y-m-d'),
+           'template' => 'payment_schedule',
+           'parameters' => [
+               'invoice_id' => $invoice->hashed_id,
+               'auto_bill' => true,
+               'schedule' => [
+                [
+                    'id' => 1,
+                    'date' => now()->format('Y-m-d'),
+                    'amount' => 40,
+                    'is_amount' => false,
+                ],
+                [
+                    'id' => 2,
+                    'date' => now()->addDays(30)->format('Y-m-d'),
+                    'amount' => 60.00,
+                    'is_amount' => false,
+                ]
+               ],
+           ],
+       ];
+
+        // $data = [
+        //     'schedule' => [
+        //         [
+        //             'id' => 1,
+        //             'date' => now()->format('Y-m-d'),
+        //             'amount' => 40,
+        //             'is_amount' => false,
+        //         ],
+        //         [
+        //             'id' => 2,
+        //             'date' => now()->addDays(30)->format('Y-m-d'),
+        //             'amount' => 60.00,
+        //             'is_amount' => false,
+        //         ]
+        //     ],
+        //     'auto_bill' => true,
+        // ];
+        
+
+
+$response = $this->withHeaders([
+    'X-API-SECRET' => config('ninja.api_secret'),
+    'X-API-TOKEN' => $this->token,
+])->postJson('/api/v1/task_schedulers', $data);
+
+        $response->assertStatus(200);
+
+
+
+$response = $this->withHeaders([
+    'X-API-SECRET' => config('ninja.api_secret'),
+    'X-API-TOKEN' => $this->token,
+])->postJson('/api/v1/task_schedulers', $data);
+
+        $response->assertStatus(422);
+
+
+    }
+
+
+    public function testPaymentScheduleWithPercentageBasedScheduleAndFailingValidation()
     {
         $invoice = Invoice::factory()->create([
             'company_id' => $this->company->id,