Function

union( array1, array2 )

Returns all unique elements from the given arrays.

Parameters

Keyword	Type	Description
array1	Any Type Array	Array to combine.
array2	Any Type Array	Array to combine.

Returns

Any Type Array, matching the type of the inputs

Examples

Find the superset of values from two integer arrays

union({1, 2, 3, 4}, {3, 4, 5, 6}) returns an array with 1, 2, 3, 4, 5, 6

Remove duplicates from an array

Remove the duplicates from an array by comparing it with an empty array of the same type:

union({1, 2, 3, 4, 1, 2}, tointeger({})) returns an array with 1, 2, 3, 4

This can also be accomplished by comparing an array with itself:

union(local!myArray, local!myArray) removes the duplicate elements from local!myArray.

Values are matched with case sensitivity

union({"a", "b"}, {"a", "B"}) returns an array with a, b, B

Array types must match

union({"a", "b"}, {1, 2}) returns the following error: Invalid types, can only act on data of the same type.

NOTE: Use either the conversion functions or the cast() function to convert to the appropriate type.

union({"a", "b"}, tostring({1, 2})) returns an array with a, b, 1, 2

Every field of a CDT, dictionary, or map must match to be treated as identical:

union({a: 1, b: 2}, {a: 1, b: 2, c: 3}) returns {{a: 1, b: 2}, {a: 1, b: 2, c: 3}}

union({a: 1, b: 2}, {a: 1, b: 2}) returns {{a: 1, b: 2}}

Null values and empty lists

Null values are included as long as they are of the correct types (nulls of an incorrect type throw a type mismatch error):

union({"a", "b"}, {"c", ""}) returns an array with a, b, c, ""

Empty lists are ignored as long as they are of the correct types (empty lists of an incorrect type throw a type mismatch error):

union(tointeger({}), {1, 2}) returns an array with 1, 2

Scalar values

Scalar values are cast to arrays with a single entry:

union(1, {2, 3}) returns an array with 1, 2, 3

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