title: How should I validate two-dimensional array in laravel
body: <p>I am new learner of laravel.Now I have to use the laravel validation in my project.The data from the form is two-dimensional array in the follwing format:</p>
  
  <pre><code>[['product_id'=&gt;1, 'quantity'=&gt;2], ['product_id' =&gt; 4, 'quantity'=&gt;5]]
  </code></pre>
  
  <p>I need to validate every product_id, how should I write the validation rule?
  thank you!</p>