Dashboard Filter Widgets by default will retrieve a distinct list of values from a particular field. In some cases its necessary to filter or limit these values in order to provide more context or hide certain values from users (i.e. NULLs) for a better experience.
Option 1: Use one or fields to create cascading filter behavior between your Filter Widgets
The example below shows two filters (Region, Province). Region is compromised of groupings of Provinces, so selecting a particular Region should equal one or more Province. If we put the “region” field in the Filter settings of the Province filter you’ll see that our Province filter values are filter within the context of the Region that we’ve selected.
You can also add a comma separated list of fields if you need to filter by more than one dimension to create more cascading filter behavior.
Option 2: Use one or fields, and additional filter expressions to your Filter Widget filter configuration.
Using our previous example, I’ve modified the Filter Fields setting to include an additional condition where we want to hide the value “Prince Edward Island” from the list of Province that are filtered after selecting a Region.
Now after we’ve set this option you’ll our Province list changes to exclude “Prince Edward Island” as expected:
This option can be especially handy for filtering out NULL or empty values from the Filter Widget value list.
Option 3: Limit default value list or search list values from a Filter Widget
If you need to limit the default value list or the number of results that return when searching for a value through a Filter widget, you can configure that option by modifying the limits in the Display Settings menu:
This option is handy for columns with high cardinality, such as an id field, and prevent the Filter Widget from loading the first 1000 values, which might be meaningless if the user will still need to search for that value anyway.
For example, we can change the maximum default values limit to 0, and the number of search results to 50.
And this will show 0 values by default, which will make the filter widget load faster.
And when search for a value will limit the search results to 50.
Also take a look at this post for further guidance with Dashboards that require more manual control over filter behavior when several filters are required to get the proper context when exploring your data.