Adding a record using a primary key defined in a rule

So far, you have seen examples of adding and updating records, where the primary key value is supplied in input. In some cases, you may want your Rulesheet to define a primary key value for a new record and then add the record to the database. To do this, you use the .new entity operator in a rule action. You can access this operator from Entity/Association Operators > Entity in the Rule Operators view.

The syntax of the new operator is:

<Entity>.new[attribute1=value, attribute2=value,… association1.attribute1=value.

Let’s model a rule that uses the new operator. In this example, assume that you need to model a rule that creates a new FlightPlan instance where an Aircraft instance has a maxCargoWeight between 100000 and 200000. If so, an Aircraft instance is assigned to the FlightPlan instance.

Create a Rulesheet named NewRecord.ers and model a rule as shown here:

The range in column 1 is written as the low limit, two dots, then the high limit. The new operator is used in the action row expression: FlightPlan.new[flightNumber=222,aircraft=Aircraft]

A flightNumber (222 in this example) must be supplied since flightNumber is the primary key for FlightPlan. The expression aircraft=Aircraft in the action row associates the Aircraft instance in input with the FlightPlan entity that will be created.

Let’s test this rule. Create a Ruletest named NewRecord.ert that uses NewRecord.ers as its test subject. Configure the Ruletest to write to the database by selecting Ruletest > Testsheet > Database Access > Read/Update. Define the following input and run the test (make sure that you provide a value such as N444D for tailNumber, since tailNumber is the primary key for Aircraft):

As you can see, a new FlightPlan instance is created with the flightNumber 222 and the Aircraft instance is assigned to it.

Let’s look at the database tables. Right-click dbo.Aircraft in the Transportation database and select Select Top 1000 Rows. You should see the following results:

A new Aircraft record has been added. Now, right-click dbo.FlightPlan and select Select Top 1000 Rows. You should see the following results:

A new FlightPlan record has been added with the flightNumber 222. It is also associated with an Aircraft bearing the tailNumber N444D.