with() Function

Function

with( localVar1, localVarN, expression )

Lets you define local variables within a function and evaluate the expression with the new variables.

See also: Grid Tutorial

Parameters

Keyword	Type	Description
localVar1	Any Type	The local variable to use when evaluating the given expression and defined using with(local!a,..., expression) or with(local!a:10, ..., expression).
localVarN	Any Type	Any additional local variables, as needed.
expression	Any Type	The expression to evaluate using the local variables' values.

Returns

Any Type

Usage considerations

In interfaces, this function differs from the load() function because it recalculates the local variable values after interactions. This recalculation always happens, even if the interaction's updates could not have impacted the variable's value. This means data queries and other slow operations in with() variables can have important performance impacts.

Defining values and domains

A local variable may be defined with or without a value, and the value may be simple or complex. When a value is not defined, it's assigned a null value.

When you don't specify the local! domain, the system first matches your variables with rules or constants with the same name, then looks for local variables with the name. Appian recommends that you always use the local! domain when referring to local variables.

Understanding types

Local variables are not assigned a type. At runtime, the type of the variable will be based on the assigned value. For example, in with(local!myvar:2, ...), myvar is of type Integer.

The type returned by the with() function will be that of the given expression.

Evaluating local variables

A local variable may reference a previously defined local variable. They are evaluated in the given order.

The local variables are only available in the evaluation of the expression.

The expression can include other variables available in its context, such as process variables and rule inputs. For example, with(local!myvar: 1, local!myvar + ri!myruleinput).

If an expression requires multiple evaluations of a complex value, you can use the with() function to define the value as a local variable, so it's only evaluated once.

Formatting

When a local variable uses the dot notation or brackets, a runtime error message will display. If the field name must contain special characters, enclose the name in single quotes.

Examples

You can copy and paste these examples into the Expression Rule Designer to see how this works.

Using Local Variables

with(local!a:10, local!b:20, local!a+local!b) returns 30

with(local!a:10, local!b:20, local!c:30, local!a+local!b+local!c) returns 60

with(local!a, isnull(local!a)) returns true

with('local!a-name':10, local!b:20, 'local!a-name'+local!b) returns 30

Using Local Variables with a Complex Value

with(local!a:getPersonForId(ri!id), local!a.firstName & " " & local!a.lastName) returns John Smith

Evaluating an Expression in the Context of a Process or Rule

When an expression is evaluated in the context of a process, the expression has access to all PV values for that process. Similarly, if the expression is used in a rule, the expression has access to all rule inputs.

with(local!a:pp!initiator, getDisplayName(local!a) & pv!b) returns John Smith123 where (pv!b=123)

with(local!a:10, ri!a) returns 100 where (ri!a=100)

Overriding Variables with the Same Identifier

If the local variable has the same domain and name (domain + name combination) as another variable in the evaluation context, the local variable is used.

with(local!a:100, with(local!a:20, local!z:10, local!a+local!z)) returns 30

with(local!a:100, local!b:1, with(local!a:20, local!z:10, local!a+local!b+local!z)) returns 31

with(ri!a:10, 2*ri!a) returns 20

Defining a Local Variable by Referencing another Local Variable

with(local!a:10, local!b:local!a*2, local!a+local!b) returns 30

with(local!a:10, with(local!b:local!a, local!c:20, local!a+local!b+local!c)) returns 40

with(local!a:local!b, local!b:10, local!a+local!b) returns error because "a" references "b" which is not available to "a"

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