title: Getstream io - create activity feed when user follow category
body: <p>I try to create activity feed with posts from category.</p>
  <p>User can follow category or tags (eq. &quot;Buddhism&quot;, &quot;Neuroscience&quot;, &quot;Psychology&quot; etc.) When user follow category or many categories I need to create personalized activity feed with posts from categories that user follow.</p>
  <p>I know that getstream have posibility to create many feed groups, but how to create activity where category is the actor? Unless I am thinking the wrong way.</p>
  <p>I create feed groups like: user, timeline, categories, articles.</p>
  <p>Feed group user show only activity that user create like: user like article, user added comment etc.</p>
  <p>and categories feed group for post from categories that user follow.</p>
  <p>I try to send activity like that:</p>
  <pre><code>    for (let category in event.result.categories) {
          const categoryFeed = client.feed('categories', category.id);
          const activity = {
              actor: `category:${category.id}`,
              verb: 'dodano przepis do kategorii',
              object: event.result.id(article ID),
              foreign_id: event.result.id(article ID),
              created_at: event.result.createdAt,
            };
          await categoryFeed.addActivity(activity);
      }
  </code></pre>
  <p>When I try run this, I see error: &quot;error: Please provide a feed slug and user id, ie client.feed(&quot;user&quot;, &quot;1&quot;)
  Error: Please provide a feed slug and user id, ie client.feed(&quot;user&quot;, &quot;1&quot;)&quot;</p>
  <p>Is there any way to create thing I need with getstream?</p>