Parameters are right now single value. You can only pick one value out of a predefined list.
What would be great is to make Parameters accept multiple values!
String Parameter for Region. I have 4 values: East, West, Central, South.
I make the Parameter multi-value (new option).
When used the parameter control allows me to choose more than one values (as many as I want) like Quick Filters work.
Automatically and by default, the list of value presented also includes "all" which can be removed (like when you customize a quick filter).
Tableau would add a logical OR between each value.
When used in a formula, I could type something like:
If [Parameter] InList (string1, string2....., stringN) Then etc.
If [Parameter] = string1 OR [Parameter] = string2 etc.
Today, you have to hard code all combination of possible values in your parameter:
East, West, Central, South, ALL, East+West, East+Central, East+South,....etc.
and code in calculated field using if then else what happens for each combination of values used. This is combersome and cannot be done if I have a lot of combination possible.
Of course, you could use Quick Filters but you do have a lot of situations where it is not possible or not the right idea, here are 2 examples:
1- you want to use the Parameter to filter across data sources (and you can't use action filters)
2- your quick filter returns a lot of values and the list is static - refreshing the quick filter each time is not good for performance for my dashboard and I would rather used a predefined list in my parameter.
--> Community Manager update [Ciara Brennan]
The 'Dynamic Parameters' feature currently available in the 2020.1 Beta may be of interest to some users that voted on this idea.
cc'ing Jim Sun as fyi