title: Create chart in Data Studio using two custom Firebase params as dimensions
body: <p>I am developing an iOS app and was asked to implement some user analytics to it. I'm using Firebase, as Google Analytics mobile will no longer be supported and it is the recommended alternative.</p>
  
  <p>In my example, I have an event that is sent to Firebase named "changed_tool" with two custom (String) params : "source" and "tool"</p>
  
  <p>I want to be able to know/see how many users have selected the "ruler" tool from the side menu, and how many have selected the same tool from a radial menu I also have.</p>
  
  <p>From what I've seen, this is not possible using the Firebase console alone, and we decided to export that data to BigQuery and use Data Studio to visualize it.</p>
  
  <p>My BigQuery table look like that : </p>
  
  <pre><code>// omitted event metrics such as date or timestamp
  "event_name": "changed_tool",
  "event_params": [ 
      {
          "key": "source",
          "value": {
              "string_value": "radial",
              "int_value": null,
              "float_value": null,
              "double_value": null
          }
      },{
          "key": "tool",
          "value": {
              "string_value": "ruler",
              "int_value": null,
              "float_value": null,
              "double_value": null
          }
      }
  ]
  // omitted event metrics
  </code></pre>
  
  <p>The only useful available dimensions Data Studio has available automatically when importing from BigQuery are "Event Name", "Event Param Name" and "Event Param Value (String)". </p>
  
  <p>How can I create in Google Data Studio a stacked column chart with, as abscissas, my tool type "dimension" (in this case ruler or protractor) and as ordinates the "Event Count" metric, with the columns being "split" by my source (radial or side) "dimension" ?</p>
  
  <p>So far, I haven't been able to split correctly my data to meet my needs, event when fiddling with filters as they seem the applied to the data is queried, not how the data is displayed.</p>