View this page in the latest version of Appian. none() Function Share Share via LinkedIn Reddit Email Copy Link Print On This Page Function none( predicate, list, context ) Calls a rule or function that returns either true or false for each item in list by asking the question, "Do all items in this list yield false for this rule/function?" with the intent to discover if no items will yield true. Parameters Keyword Type Description predicate Function, Rule, or Data Type Constructor Expression that returns a Boolean (true or false). list Any Type Array List of elements that the predicate iterates through. context Any Type Array Variable number of parameters passed directly into each predicate evaluation. Returns Boolean Usage considerations Referencing expressions and rules Use fn!functionName or a!functionName to reference an expression function and rule!ruleName to reference a rule. Using rules or functions with multiple arguments To use rules or functions that take more than two arguments, use the merge() function. For example, given a rule g(x, y, z), reduce(rule!g, i, merge({a, b, c}, {d, e, f})) returns g(g(g(i, a, d), b, e), c, f). Understanding results Returns false as soon as the returned value of an evaluation yields true; otherwise, returns true. Empty and null lists yield true. Limitations a!forEach() cannot be used within rules used in this function. Examples Generalized behavior Given a function f(x), none(fn!f, {a, b, c}, v) returns not(or({f(a, v), f(b, v), f(c, v)})) Checking items in a list 1 2 3 4 none( a!isNullOrEmpty, {1, 2, null, 3, null, 4} ) Returns false. Checking items in an empty list 1 2 3 4 none( a!isNullOrEmpty, {} ) Returns true. Checking items with context To help demonstrate how the context parameter works in looping expressions, let's look at an example. Imagine you're building an expression that uses looping to analyze group membership in your application. You have four Group constants configured in the following ways: Constant Group(s) referenced Group membership cons!csaAdmins CSA Administrators user1, user3 cons!csaProfs CSA Professors user1, user2, user4, user5, user6, user7 cons!csaBuilding1 CSA Building 1 user1, user2, user3, user5, user6, user7 cons!allGroups CSA Adminstrators, CSA Professors, CSA Building 1 See above The following SAIL expressions reference these constants to show how context works when checking items in a list. Note: You'll need to adapt these expression examples for your own purposes, since the examples reference constants that may not exist in your Appian environment. Checking items in a list with context 1 2 3 4 5 none( a!isUserMemberOfGroup, {"user1", "user2", "user3"}, cons!csaAdmins ) Returns false when user1 and user3 are members of the group referenced by cons!csaAdmins. a!isUserMemberOfGroup has 3 parameters: username, groups, and matchAllGroups. The none() list corresponds to username, and the list of values provided in the context parameter are used as the next two parameters, groups & matchAllGroups. Learn more about a!isUserMemberOfGroup(). Checking items in a list with context for more than 2 parameters 1 2 3 4 5 none( a!isUserMemberOfGroup, {"user1", "user2", "user3"}, {cons!allGroups, true} ) Returns false when user1 is a member of all the groups referenced in cons!allGroups. a!isUserMemberOfGroup has 3 parameters: username, groups, and matchAllGroups. The none() list corresponds to username, and the list of values provided in the context parameter are used as the next two parameters, groups & matchAllGroups. Learn more about a!isUserMemberOfGroup(). Checking all items in a list with context for more than 2 parameters which accept lists 1 2 3 4 5 none( a!isUserMemberOfGroup, {"user1", "user2", "user3"}, merge({cons!csaAdmins, cons!csaProfs}, {true, true}) ) Returns false when user1 is a member of the groups referenced in cons!csaAdmins and cons!csaProfs. The merge function maps the list values to the correct parameters in this example. Learn more about a!isUserMemberOfGroup(). Checking a list with a custom expression rule In this example, we will use a helper rule, rule!isDateLater(value, referenceDate), which is defined as: 1 ri!value > ri!referenceDate Example filter: 1 2 3 4 5 none( rule!isDateLater, {date(1950, 2, 3), date(1950, 6, 23), date(1950, 5, 2)}, date(1950, 4, 7) ) Returns false. 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 Incompatible Cannot be used to configure a process report. Process Events Incompatible Cannot be used to configure a process event node, such as a start event or timer event. Feedback Was this page helpful? SHARE FEEDBACK Loading...