List helpers in $util.list - AWS AppSync

List helpers in $util.list

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$util.list contains methods to help with common List operations such as removing or retaining items from a list for filtering use cases.

$util.list.copyAndRetainAll(List, List) : List

Makes a shallow copy of the supplied list in the first argument while retaining only the items specified in the second argument, if they are present. All other items will be removed from the copy.

$util.list.copyAndRemoveAll(List, List) : List

Makes a shallow copy of the supplied list in the first argument while removing any items where the item is specified in the second argument, if they are present. All other items will be retained in the copy.

$util.list.sortList(List, Boolean, String) : List

Sorts a list of objects, which is provided in the first argument. If the second argument is true, the list is sorted in a descending manner; if the second argument is false, the list is sorted in an ascending manner. The third argument is the string name of the property used to sort a list of custom objects. If it's a list of just Strings, Integers, Floats, or Doubles, the third argument can be any random string. If all of the objects are not from the same class, the original list is returned. Only lists containing a maximum of 1000 objects are supported. The following is an example of this utility's usage:

INPUT: $util.list.sortList([{"description":"youngest", "age":5},{"description":"middle", "age":45}, {"description":"oldest", "age":85}], false, "description") OUTPUT: [{"description":"middle", "age":45}, {"description":"oldest", "age":85}, {"description":"youngest", "age":5}]