In this question, someone asked how to add a query parameter to BigQuery and connect it to Data Studio. Someone answered and said to use a custom query and 'add the field as a parameter'. They use the same images and examples that are used in this Google blog post and I cannot figure out how to make a field into a parameter based on either of these sources.
It looks to me like you can only create a list of text values, numbers, or specify a Boolean parameter. Ideally, I don't want to manually create a list of values based on the field since the values in the field might change over time. I want to be able to use these parameters in the Custom Query's WHERE clause so that data is dynamically filtered as the user selects the different parameter options. Using a multi-select option is required, so this would require filling a string array for the parameter, with the default setting to be including all of the possible values (or being able to change WHERE company IN UNNEST(@company) to WHERE company = company.
Edit: This question is pretty much what I'm after, but I cannot figure out how to fill a parameter with dimension values. This looks like it might not be possible, as there are issues in the Issue Tracker that relate to this capability.