Given an array with null values, how would you return a new array without any nulls in Appian?

Use the reject function to filter out all null values from the array.

Code:

Output:

Explanation:

a!localVariables(...) creates a scope for local variables. Variables defined inside are available only within that scope, and the last argument is the value the expression returns.

1. local!data: { 1, null, 6, 8, null, 19, 30, null } defines a list of eight items, three of them null.
2. reject(fn!isnull, local!data) takes a predicate function and a list, runs the function on each item, and drops every item for which it returns true. With isnull() as the predicate, every null item is removed.

Replacing null values with Zero in Appian:

Sometimes Interviewer may ask a follow up replace the "null" with default value, in your case let replace the "null" with default value - zero

Code:

Output:

Explanation:

a!forEach(local!data, if(a!isNullOrEmpty(fv!item), 0, fv!item)) loops over a list, runs an expression on each item, and returns a new list of the results.

What happens in the loop

1. a!forEach goes through the items in local!data one at a time, in order.
2. On each pass, fv!item holds the current item.
3. if(a!isNullOrEmpty(fv!item), 0, fv!item) returns 0 when the item is null or empty, and the item itself otherwise.
4. When the last item is done, a!forEach returns all the results as a new list.

Step by step with { 1, null, 6, 8, null, 19, 30, null }

Result

The result has the same length and order as the original, with each null replaced by 0. local!data itself doesn’t change.