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A decision is an element that makes a choice based on a condition and follows one and only one of the outgoing sequence flows. For example, you need to use a decision to show different order forms for the customers with different grades, or to prevent a blocked customer from making orders.
An example of decision properties is represented in the image below:
The decision properties pane consists of the following sections:
For more information, see the Caption section in Common Properties.
2.1.2 Decision Type
Decision type defines whether an expression or a rule is used to define conditions of the decision. Possible decision types are described in the table below:
|Expression||Expressions can be used to create or change an object or a variable based on logic.|
|Rule||A rule is a special kind of microflow, the outcomes of which can be used in a decision instead of calling a sub-microflow and using the return variable of that sub-microflow. The idea is that complicated decisions can be consolidated in rules and reused in various places.|
If the Type property is set to Expression, the expression entered here is used to define the condition of the decision. For more information on expressions, see Microflow Expressions.
The expression should result in a Boolean or an enumeration.
For the expression resulting in a Boolean, two flows are possible: true and false. For example, you can use the expression resulting in a Boolean if you want to check whether a customer’s email is verified or not.
The number of conditions available for the enumeration type depends on the corresponding enumeration values. There is also the empty condition available for enumeration: if the enumeration parameter or an attribute of an object is unassigned, the sequence flow with the caption (empty) is followed.
If you want to open a different order form per customer grade you can use a decision. The microflow parameter is Customer. Depending on what grade the customer has, a different sequence flow is followed and a different order form is opened. If an end-user needs to select a customer grade but does not do that, the flow labelled (empty) is followed and an error message is shown to the end-user.
Since you want to go in a different direction for each value of the enumeration, you only need to use the attribute containing the enumeration. So the expression in the example above is
If the Type property is set to Rule, a rule can be selected to define the condition of the decision. You can use the outcome of the rule for the decision instead of calling a sub-microflow and using the return variable of that sub-microflow.
The properties of the Rule decision type are the following ones:
Rule – allows you to select a rule.
Parameter – for each parameter of the rule an argument needs to be specified using expressions. For example, a rule that determines whether a customer deserves a certain status will have a customer object as a parameter.
2.1.3 Error Handling Type
For more information, see the Error Handling Type section in Common Properties.