title: How to use IN operator with a GET request of Yii2REST web service
body: <p>The documentation of Yii2 REST Web Services explain that we can filter the searched collection through query params passed via URL in a GET HTTP request.</p>
  
  <p>From doc:
  "Addionally, you can sort collections like <a href="http://localhost/users?sort=email" rel="noreferrer">http://localhost/users?sort=email</a> or <a href="http://localhost/users?sort=-email" rel="noreferrer">http://localhost/users?sort=-email</a>. <strong>Filtering collections</strong> like <a href="http://localhost/users?filter[id]=10" rel="noreferrer">http://localhost/users?filter[id]=10</a> or <a href="http://localhost/users?filter[email][like]=gmail.com" rel="noreferrer">http://localhost/users?filter[email][like]=gmail.com</a> could be implemented using <strong>data filters</strong>"</p>
  
  <p>My question is how to use query params for an IN condition?</p>
  
  <p>The IN condition is supported by data filter class of the framework but It does not work as I am doing it. I tried these:</p>
  
  <p><a href="http://localhost/api/v1/users?filter[id][in][]=1,2,3" rel="noreferrer">http://localhost/api/v1/users?filter[id][in][]=1,2,3</a> (return empty response)
  <a href="http://localhost/api/v1/users?filter[id][in]=[1,2,3]" rel="noreferrer">http://localhost/api/v1/users?filter[id][in]=[1,2,3]</a> (return error message 'Operator "in" requires multiple operands.')</p>
  
  <p>...and other ways same situation</p>