While or do while logic in expression rule

Question

How to implement while or do while logic in expression rule?

Harshit Bumb (Appyzie) · Answer

You cannot implement a while or a do while loop in Appian. You only have to live with a!forEach. It expects a list to operate on. This loop will run once for every item in the list. 
 Now to exit the loop in between, is not possible. But what is possible is to set the output value after your condition to null and then outside the loop, remove all the null values using reject() function.

Aparajita Singh · Answer

We do not have a looping function that would stop based on a condition. All you can do is use a!forEach just like Harshit mentioned in his answer. You might have to do it in multiple steps, at least two. The first one to exclude values greater than 31, for which you can use filter, reject, wherecontains, and/or a!forEach. Second step would be to update each item in array based on the condition specified inside the while loop, for this you can use a!forEach.

Harshit Bumb (Appyzie) · Answer

shreeharshan0678 a!localVariables(
 local!keyValPair: {
 {
 id: 1,
 value: "This is a text value"
 },
 {
 id: 2,
 value: 12
 },
 {
 id: 3,
 value: {1,2,3,4}
 }
 },
 displayvalue(
 12 /*Desired value that you want*/,
 local!keyValPair.value /*Place where you want to search it for*/,
 local!keyValPair.id /*Field of the matching index that you wnat to return */,
 "Not available" /*Default value if the desired value was not found*/
 )
)