Types of expressions in expression editor

JavaBean Expression

The expression we introduced in BMC Helix Platform is called JavaBean expression. The syntax is based on UEL (Unified Expression Language), and used in JSP 2.0 (Java Server Page). The word "JavaBean" comes from JSP where it uses the expression to access JavaBeans. The dots in the expression is to navigate to properties of the bean. Notation "${}" is used to dereference the expression to a value.  

Assignment

Assignment is about assigning some value to a target. It has an assignment target and a value expression. Both can be JavaBean expressions. The value expression can have arithmetic operations (+, -, *, /, %), with each value expression surrounded by dereference notation "${}",

Condition

The expression for the condition has to be evaluated to a boolean value- true or false. Condition expression can have arithmetic operations (+, -, *, /, %) on value expressions; relational operations (>, <, =, !=, >=, <=) on value expressions; and logical operations (AND, OR, NOT) on relational operations.

Context Indicator

In the value expression, the first part of the expression is the context indicator. Here are context indicators we support today, and how they are used:

processContext

The value is from a process variable, which can be process input, output or local variable. If the variable is a non-primitive, i.e. record instance or a java object, you can use "." to navigate to fields/properties of the non-primitive object.

To use a dynamic variable in a string, you can simply type the $variable name in the string and the value of the variable is inserted in the string at runtime.

For example:

“Hi $user, your ticket is created. The id is $ticketId. You can view the ticket details at $ticketLink.”

When you use any field, variable, or keyword within a string expression, it will be evaluated to the value at runtime. If you want to use the variable name and not its value in the expression, then add an escape character (\) to the expression.

For example, "$\{processContext.processVariableName}".

activityResults

The value is from the result of a process activity.

userTask

This context is only applicable to Process UserTask completion condition. It resolves to the UserTask record instance. 

ruleContext

the value is from the record instance that triggers the rule.

actionResult

the value is from the result of the current rule action.

recordContext

the value is from the record instance that the grid is operating on.

view

The value is from a view component

Items in a collection

List

we use "[]" notation with numerical index. For example, output[0]

Map

we use "[]" notation with the map key being a string. For example, values["Short Description"]

Associated record instances

From JavaBean point of view, when two record instances are associated, the associated record instance can be interpreted as the property of the first record instance. For example, when Employee record is associated with Department record, we can also interpret Department being a property of Employee. Therefore, using JavaBean expression, we can naturally navigate from one record instance to associated record instances.

Keywords

Keywords can be used in the expression. They are resolved to a value during the runtime. Keywords are available under the "General" subtree of the expression dictionary UI. Here are supported keywords in BMC Helix Platform, and the value each keyword is resolved to. Some of the keywords are only applicable to a particular definition.

When you use any keyword within a string expression, it will be evaluated to the value at runtime. If you want to use the variable name and not its value in the expression, then add an escape character (\) to the expression.

For example, "$\{processContext.processVariableName}".

Current Date

This keyword resolves to the current date, and the time defaults to midnight.

Current Date and Time

This keyword resolves to the current date and time.

Current Group IDs

This keyword resolves to the list of the group IDs of which the current user is a member. If there are no groups, the value is an empty string. If there are groups, the value is a string displayed in the following format:;<groupID>;<groupID>;<groupID>;

Current Groups

This keyword resolves to the list the group names of which the current user is a member. If there are no groups, the value is an empty string. If there are groups, the value is a string displayed in the following format: <groupName> <groupName> <groupName>

Current Operation

This keyword resolves to the current record operation. This keyword is only applicable to a rule definition.

Current Record

This keyword resolves to the current record rule is operating on. This keyword is only applicable to a rule definition.

Current Record Definition Name

This keyword resolves to the current record definition name. This keyword is only applicable to a rule definition.

Current Roles

This keyword resolves to names of the list of roles that map to groups to which the current user belongs. If there are no roles or no mapped groups, the value is an empty string. If there are mapped roles, the value is a string displayed in the following format: <roleName> <roleName> <roleName>

Current Server URL

This keyword resolves to the URL of the current server. It is in the format of http://<hostname>:<port> or https://<hostname>:<port>, depending on if SSL is configured or not. The host name here is the server external name, which is visible outside of the firewall.

Current Time

This keyword resolves to the current time.

Current User

This keyword resolves to the current logged in user.

Current User Locale

This keyword resolves to the language and country code for the current logged in user. It is in the format of <language>_<countryCode>

Current Week Day

This keyword resolves to the current day of the week

Process Correlation ID

This keyword resolves to the process correlation id. The correlation id can be used to uniquely identify a process instance execution. If the process is in a parallel execution through parallel gateway or parallel multi-instance loop, using this keyword in the parallel path, it generates separate correlation id to identify each execution path. This keyword is only applicable to a process definition.

Supported Data Type

• Expression supports all Rx data types except Attachment. The supported data types are Integer, Floating, Decimal, Selection, Boolean, Date, Date/Time, Time, Text.  
• Process expression and rule expression supports Record Instance, Custom Java Object (developer defined Java object).
• Action supports Map and List as the Action input parameters, but with restrictions. The restrictions are the following:
  Map

  • Map key being a constant, but map value is an expression. the key value pairs are itemized explicitly:

    The JSON of the action definition input map 
    {
      "assignTarget": "values[\"Description\"]",
      "expression": "${processContext.name}"
    },
    {
      "assignTarget": "values[\"Submitter\"]",
      "expression": "$USER$"
    }
    
    FooServiceImpl.java:
    @Action()
    public RecordInstance createSomething(
             @ActionParameter(name = "values") Map<String, String> values) {
    ...
    }

  • An action that returns a map can be used as the map input of the next action.

  List

  • A comma separated string can be used as the input value for List<String> parameter.

  • An action that returns a list can be used as the list input of the next action.