Arcadia filters set parameters at the dashboard level. Depending on the type of filter (date range, single select, multi-select), the parameter values will look different and the custom expression you use will be different. If you haven’t already, please watch the intro training video 08. Intro to Parameters
You can always look at the current parameter by looking at the filter funnel at the top right of the dashboard.
This is how to interpret what you see:
There are 3 types of filters, each of which requires slightly different setup. The basic setup of the custom expressions will look like this:
Show all values when no filter is selected
Useful for when you want to create a visual with parameters but by default display everything or remain unfiltered until someone selects a parameter to filter by.
The technique involves using a custom expression as a parameter.
Create a base visual with a filter containing this expression:
By forcing the default value of the parameter to -1 and if nothing is selected all data will be shown, because (1=1) is used.