In the case list screen it is often useful to display the history of a tracked value like patient weight or blood pressure. This can be done by following the Incrementing a counter trick, but using a string concatenation instead of an increment:
- "weight" is a number question in the form.
- "weight_history" is a case property that tracks the history of weight values
- "new_weight_history" is a hidden value that calculates the new weight history, including the current answer for "weight". This gets saved back to the case property "weight_history"
In the calculate condition for "new_weight_history", you use the concat function to add the answer to the weight question to the weight_history:
concat(#case/. The final dash is a separator that ensures the weight history can be easily read.