Django Rest Framework : How to add a custom field to the response of the GET request?
<p>I'm new to DRF and have just started building an API. </p>

<p>I've a model called <strong>Shop</strong>.
And I've two user different user types : <strong>Customer</strong> and <strong>Supplier</strong>.</p>

<ol>
<li>I want to add a custom field <strong>distance</strong> to the response of the GET request <strong>/shops/id/</strong>, which represents the distance between the Customer that is submitted the request and the corresponding shop. </li>
<li>I think I cannot use <em>SerializerMethodField</em> since the value of the method is not only depend on the object itself. </li>
<li>I do not want to add this custom field for all GET requests, instead, I need to add it, when the user that is submitted the request is a <strong>Customer</strong>. </li>
</ol>

<p>Considering constraints above, how should I add the custom field to the response of the request? What's the best way to do this ?</p>