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length() Function


length( array )

This function returns the number of elements in an array.

See also:

  • isnull(): Use this function to determine if the process variable or array contains null values.
  • count(): Use this function to include null elements in the number of elements in a process variable or array.


Keyword Type Description


Any Type Array

The array in which to calculate the number of elements.



Usage considerations

Null elements

In most cases, this function does not count null elements. length({null, 2}) returns 1 because the null is not counted.

There are scenarios though where null values will be counted as part of a list. For example, let's say you have a local variable called local!result, which stores the results of a query. If the query returns a null value, then the expression length({local!result, 2}) may return 2. When local!result is a List of Text String with a single null field, Appian evaluates the expression as length({{null}, 2}) and returns 2.

Check length of array containing a null list

If this function is used on a null result from the Query Database smart service, the expression may fail to evaluate and cause an error. To avoid an error, first check the result set for a null value using the isnull() function before attempting to count the result set using the length() function.


Length of list

length({10, 20, 30})

Returns 3.

Length of list with null values

length({10, null, 30})

Returns 2. Null values are skipped.

Length of list with nested list

length({1, 2, merge({1}, {2})})

Returns 3. Nested lists are counted as one value.

Length of list with nested null list

length({1, 2, merge({null})})

Returns 3. Nested lists with only null values are counted as one value.

Feature compatibility

The table below lists this function's compatibility with various features in Appian.
Feature Compatibility Note
Portals Compatible
Offline Mobile Compatible
Sync-Time Custom Record Fields Compatible

Can be used to create a custom record field that only evaluates at sync time.

Real-Time Custom Record Fields Incompatible

Custom record fields that evaluate in real time must be configured using one or more Custom Field functions.

Process Reports Compatible
Process Events Compatible

length() Function