List functions list-functions

differenceLists(listString,listString): listString

differenceLists(listInteger,listInteger): listInteger

differenceLists(listDecimal,listDecimal): listDecimal

differenceLists(listBoolean,listBoolean): listBoolean

differenceLists(listDuration,listDuration): listDuration

differenceLists(listDateTime,listDateTime): listDateTime

differenceLists(listDateTimeOnly,listDateTimeOnly): listDateTimeOnly

differenceLists(listDateOnly,listDateOnly): listDateOnly

differenceLists(['a','b','c'], ['b'])

Returns ['a','c'].

differenceLists(['a','a','b'], [])

Returns ['a','b'].

differenceLists([], ['a'])

Returns [].

distinct(<listInteger>)

Returns a list of integers.

distinct(<listDecimal>)

Returns a list of decimals.

distinct(<listString>)

Returns a list of strings.

distinct(<listDateTimeOnly>)

Returns a list of datetimes without considering time zone.

distinct(<listDateTime>)

Returns a list of datetimes.

distinct(<listDateOnly>)

Returns a list of dates.

distinct(<listBoolean>)

Returns a list of booleans.

distinct(<listDuration>)

Returns a list of durations.

distinct(<listObject>)

distinct(<listObject>,<string>)

Returns a list of objects.

distinct([10,2,10,null])

Returns [10, 2].

distinctWithNull(<listInteger>)

Returns a list of integers.

distinctWithNull(<listDecimal>)

Returns a list of decimals.

distinctWithNull(<listString>)

Returns a list of strings.

distinctWithNull(<listDateTimeOnly>)

Returns a list of datetimes without considering time zone.

distinctWithNull(<listDateTime>)

Returns a list of datetimes.

distinctWithNull(<listDateOnly>)

Returns a list of dates.

distinctWithNull(<listBoolean>)

Returns a list of booleans.

distinctWithNull(<listDuration>)

Returns a list of durations.

distinctWithNull([10,2,10,null])

Returns [10, 2, null]

filter(listObject, string, listString)

filter(listObject, string, listInteger)

filter(listObject, string, listDecimal)

filter(listObject, string, listDateTime)

filter(listObject, string, listDateTimeOnly)

filter(listObject, string, listDateOnly)

filter(listObject, string, listDuration)

filter(listObject, string, listBoolean)

Returns a listObject.

Here is an example of a payload passed in an incoming event “myevent”:

"productListItems": [{
   "id": "product1",
   "name": "the product 1",
   "price": 20
},{
   "id": "product2",
   "name": "the product 2",
   "price": 30
},{
   "id": "product3",
   "name": "the product 3",
   "price": 50
}]

You can use the following expression:

filter(
 @event{myevent.productListItems},
 "id",
 ["product2", "product3", "product4"]
)

Returns a listObject containing the two objects with “product2” and “product3” as id.

getListItem(<listInteger>,<index>)

Returns an integer.

getListItem(<listDecimal>,<index>)

Returns a decimal.

getListItem(<listString>,<index>)

Returns a string.

getListItem(<listDateTimeOnly>,<index>)

Returns a datetime without considering time zone.

getListItem(<listDateTime>,<index>)

Returns a datetime.

getListItem(<listDateOnly>,<index>)

Returns a list of dates.

getListItem(<listBoolean>,<index>)

Returns a boolean.

getListItem(<listDuration>,<index>)

Returns a duration.

getListItem([10, 2, 3], 1)

Returns “2”

getListItem(["A", "B", "C"], 2)

Returns “C”

Examples with an event field ‘event.appVersion’ with value: “20.45.2.3434”

split(@event{event.appVersion}, "\\.")

Returns ["20", "45", "2", "3434"]

getListItem(split(@event{event.appVersion}, "\\."), 0)

Returns “20”

in(<integer>,<listInteger>)

in(<decimal>,<listDecimal>)

in(<string>,<listString>)

in(<boolean>,<listBoolean>)

in(<dateTimeOnly>,<listDateTimeOnly>)

in(<dateTime>,<listDateTime>)

in(<dateOnly>,<listDateOnly>)

in(<duration>,<listDuration>)

Return a boolean.

in(4,[4,5,3,4])

Returns true.

in(8,[4,5,3,4])

Returns false.

in(#{ExperiencePlatform.ProfileFieldGroup.profile.person.gender}, ["male"])

intersect(listString,listString): listString

intersect(listDecimal,listDecimal): listDecimal

intersect(listInteger,listInteger): listInteger

intersect(listDateTime,listDateTime): listDateTime

intersect(listDateTimeOnly,listDateTimeOnly): listDateTimeOnly

intersect(listDateOnly,listDateOnly): listDateOnly

intersect(listDuration,listDuration): listDuration

intersect(listBoolean,listBoolean): listBoolean

Returns a list.

intersect(
    ["sports", "news", "documentary"],
    ["sports", "movies", "documentary"]
)

Returns [“sports”, “news”]

intersect(
    #{ExperienceDataPlatform.profile.interests},
    ["sports", "documentary"]
)

Returns common items between profile attributes and given list of categories.

intersect(
    #{ExperienceDataPlatform.profile.interests},
        @event{myEvent.sport_interests}
)

Returns common items between profile attributes and given event field.

limit(<listString>,<integer>)

limit(<listString>,<integer>,<boolean>)

Returns a list of strings.

limit(<listInteger>,<integer>)

limit(<listInteger>,<integer>,<boolean>)

Returns a list of integers.

limit(<listDecimal>,<integer>)

limit(<listDecimal>,<integer>,<boolean>)

Returns a list of decimals.

limit(<listBoolean>,<integer>)

limit(<listBoolean>,<integer>,<boolean>)

Returns a list of booleans.

limit(<listDateOnly>,<integer>)

limit(<listDateOnly>,<integer>,<boolean>)

Returns a list of dates.

limit(<listDateTimeOnly>,<integer>)

limit(<listDateTimeOnly>,<integer>,<boolean>)

Returns a list of datetimes without considering time zone.

limit(<listDateTime>,integer>)

limit(<listDateTime>,<integer>,<boolean>)

Returns a list of datetimes.

limit(<listDuration>,<integer>)

limit(<listDuration>,<integer>,<boolean>)

Returns a list of durations.

limit(<listObject>,<integer>)

limit(<listObject>,<integer>,<boolean>)

Returns a list of objects.

limit(["A", "B", "C", "D", "E"], 3)

Returns ["A","B","C"].

limit(["A", "B", "C", "D", "E"], 3, false)

Returns ["C","D","E"].

listSize(<listInteger>)

listSize(<listDecimal>)

listSize(<listString>)

listSize(<listBoolean>)

listSize(<listDateTimeOnly>)

listSize(<listDateTime>)

listSize(<listDateOnly>)

listSize(<listDuration>)

Return an integer.

listSize(<listObject>)

listSize([10,2,3])

Returns 3.

listSize(@event{my_event.productListItems})

Returns the number of objects in the given array of objects (listObject type).

mergeLists(listString,listString,boolean): listString

mergeLists(listInteger,listInteger,boolean): listInteger

mergeLists(listDecimal,listDecimal,boolean): listDecimal

mergeLists(listBoolean,listBoolean,boolean): listBoolean

mergeLists(listDuration,listDuration,boolean): listDuration

mergeLists(listDateTime,listDateTime,boolean): listDateTime

mergeLists(listDateTimeOnly,listDateTimeOnly,boolean): listDateTimeOnly

mergeLists(listDateOnly,listDateOnly,boolean): listDateOnly

mergeLists(['a','b'], ['b','c'], true)

Returns ['a','b','c'].

mergeLists(['a','b'], ['b','c'], false)

Returns ['a','b','b','c'].

serializeList(<listInteger>,<string>,<boolean>)

serializeList(<listDecimal>,<string>,<boolean>)

serializeList(<listString>,<string>,<boolean>)

serializeList(<listBoolean>,<string>,<boolean>)

serializeList(<listDateTimeOnly>,<string>,<boolean>)

serializeList(<listDateTime>,<string>,<boolean>)

serializeList(<listDateOnly>,<string>,<boolean>)

serializeList(<listDuration>,<string>,<boolean>)

Return a string.

serializeList(["Hello","World"], " ", false)

Returns “Hello World”.

serializeList(["Hello", "World"], ",", true)

Returns ““Hello”,“World””.

sort(<listInteger>,<boolean>)

Returns a list of integers.

sort(<listDecimal>,<boolean>)

Returns a list of decimals.

sort(<listString>,<boolean>)

Returns a list of strings.

sort(<listDateTimeOnly>,<boolean>)

Returns a list of datetimes without considering time zone.

sort(<listDateTime>,<boolean>)

Returns a list of datetimes.

sort(<listDateOnly>,<boolean>)

Returns a list of dates.

sort(<listBoolean>,<boolean>)

Returns a list of booleans.

sort(<listObject>,<string>,<boolean>)

Returns a list of objects.

sort(["A", "C", "B"], true)

Returns ["A","B","C"].

sort([1, 3, 2], false)

Returns [3, 2, 1].

sort(@event{my_event.productListItems}, "SKU", true)

Returns the listObject ordered by SKU attribute (ascending order)

This section contains structured knowledge intended to support interpretation, retrieval, and question answering related to this topic.

For complete understanding, this information should be combined with the documentation on this page. Neither source is intended to stand alone; the page describes the feature, while this section provides additional context that helps disambiguate terminology, intent, applicability, and constraints.

• TL;DR: This page documents all list functions available in AJO journey expressions, covering how to filter, sort, deduplicate, check membership, limit, serialize, merge, subtract, and find intersections of lists and arrays.

Intents:

• Remove duplicate values from a list using distinct (ignoring nulls) or distinctWithNull (preserving nulls)
• Filter a listObject to return only objects matching specific key values using filter
• Retrieve an element at a specific index from a list using getListItem
• Check whether a value exists in a list using in
• Find common elements between two lists using intersect
• Combine two lists, with or without deduplication, using mergeLists
• Subtract one list from another (set difference) using differenceLists
• Return the first or last N elements of a list using limit
• Count the total number of elements in a list using listSize
• Convert a list to a delimited string using serializeList
• Sort a list in ascending or descending order using sort

Glossary:

• listObject: A list of complex objects that must be a field reference; cannot contain null objects (product-specific)
• keyAttributeName: An optional string parameter used with distinct, filter, and sort to identify which object attribute to use for deduplication, filtering, or sorting (product-specific)
• intersect: A set operation returning only the elements present in both input lists
• mergeLists: A set operation returning the union (deduplicated) or concatenation (with duplicates) of two lists, depending on the deduplicate parameter (product-specific)
• differenceLists: A set operation returning the items of the first list that are not present in the second list (product-specific)

Guardrails:

• distinctWithNull does not support the <listObject> parameter type
• filter requires the listObject parameter to be a field reference, not an inline literal
• listSize on a listObject requires the list to be a field reference; a listObject cannot contain null objects
• serializeList does not support the listObject type
• mergeLists and differenceLists only support scalar list types (string, integer, decimal, boolean, dateTime, dateTimeOnly, dateOnly, duration); listObject is not supported
• mergeLists’s deduplicate parameter must be a literal true/false, not a dynamic boolean expression
• differenceLists always deduplicates its result; there is no option to keep duplicates

Terminology:

• Canonical name: List functions — Acronym: none — variants: collection functions, array functions
• Synonyms: “listSize” = “count list elements”; “serializeList” = “join list to string”
• Do not confuse: “distinct” (ignores nulls) ≠ “distinctWithNull” (preserves null as a distinct value)
• Do not confuse: “limit” with third parameter true (returns first N items) ≠ “limit” with false (returns last N items)
• Do not confuse: “intersect” (common elements between two lists) ≠ “filter” (elements matching specific key values)
• Do not confuse: “mergeLists” (combines two lists, union or concatenation) ≠ “differenceLists” (subtracts one list from another) ≠ “intersect” (common elements only)

FAQ:

• Q: How do I get the first 3 items of a list? — Use limit(myList, 3) or limit(myList, 3, true); the default is to return the first items.
• Q: How do I get the last 3 items of a list? — Use limit(myList, 3, false).
• Q: What is the difference between distinct and distinctWithNull? — distinct ignores null values and excludes them from the result; distinctWithNull treats null as a distinct value and includes one null entry if any nulls are present.
• Q: Can I filter a list of strings with filter? — No, filter only works on listObject; for scalar lists use in or distinct for deduplication.
• Q: How do I check if a value is in a list? — Use in(value, myList), which returns true if the value is found in the list.
• Q: Can I sort a listObject by a specific attribute? — Yes, use sort(@event{...}, "attributeName", true) where the second parameter is the attribute name and the third is the sort direction (true = ascending).
• Q: How do I combine two lists and remove duplicates? — Use mergeLists(list1, list2, true).
• Q: How do I combine two lists but keep duplicate values? — Use mergeLists(list1, list2, false).
• Q: How do I find the items in one list that are not in another? — Use differenceLists(list1, list2), which returns the items of list1 not present in list2.
• Q: What is the difference between intersect and differenceLists? — intersect returns items common to both lists; differenceLists returns items in the first list that are absent from the second list.