Processing the Individual Records: Use of Record Constructor¶
In this section, we show how to use the “Record Constructor” component. This component allows applying data transformations on a record using user-defined expressions. It also allows merging several simple values, records or lists in one single record.
In our example, in the previous section we showed the Iterator component returns a data record in each iteration. In this section, we will use the “Record Constructor” component to perform a simple transformation in the extracted records. More precisely, we will add three new data fields to each record specifying the day of the month, the month and the year when the message was received. The value of these data fields will be obtained by applying simple expressions on the DATE field extracted from the page.
Add the “Record Constructor” component ( icon) to the workspace and add it to the current process, as indicated in Use of the Record Constructor component, setting its name to “MainRecordConstructor” and its output to “MAILMESSAGEOUT”. The output record that the iterator returns on each iteration will be taken as input by the Record Constructor component.
The component is configured as follows: first, select the set of records that can be combined in this component using the input configuration area. In this case, only one will be used, the one called WEBMAIL. Click on the icon to the right of “Input Values” to view a selection list from where “WEBMAIL” is chosen.
Once this has been done, double-click on the component to access its wizard. In this case, we want to return the WEBMAIL fields SENDER, SUBJECT, and SIZE, along with three new fields, MESSAGEDAY (that will return the day on which the message was delivered), MESSAGEMONTH (the month), and MESSAGEYEAR (the year), created. The fields obtained from the component input (WEBMAIL) are shown in the upper half of the window. All fields are disabled by default. In order to use them in the output record, simply click once with the left-hand button of the mouse on the icon for each one. By clicking on the icon, the field is disabled again.
The bottom half of the wizard allows adding new fields to the output structure, which can be derived from the input fields. Click on the button to the right of the “User defined fields” message to create new derived attributes. Click it three times and name each one as MESSAGEDAY, MESSAGEMONTH and MESSAGEYEAR, respectively.
Record editor shows the result of the operation after naming the output record fields.
As can be seen, at the top of the window is an error indicating that some attributes have not yet been defined.
Editing New Record Fields¶
Next to each defined field a text box allows specifying the field value. The section Appendix A: ITPilot Operators describes each of the functions that can be used in these expressions. In our example, the three new fields will respectively be created by using the GETDAY, GETMONTH and GETYEAR functions, which accept a DATE-type parameter as input and respectively return an integer that indicates the day, the month and the year of the received data.
The expression can be directly typed in the “Expression value” box (e.g. GETDAY (WEBMAIL.MESSAGEDATE). Auto-complete features are available so the user does not need to remember neither the name/parameters of the available functions nor the name of the available fields. If the written expression is wrong, it is highlighted in red and an explanatory message of the error appears as a tooltip of the incorrect part. For very long expressions user can click the button to open a bigger box in a new window.
After the expressions for the three new fields have been created (GETDAY(WEBMAIL.MESSAGEDATE), GETMONTH(WEBMAIL.MESSAGEDATE) and GETYEAR(WEBMAIL.MESSAGEDATE)), the result will be similar to that shown in Final result of the Record Constructor component.