Creating tMap expressions

In the previous example, we demonstrated how to manipulate the schemas and basic mapping of input columns to output columns. This recipe will show how to add much more complex rules to tMap and how to use the Talend supplied functions.

Expressions are limited to a single line of Java code, but can contain any of the following:

• Constants
• Input variables
• The globalMap and context variables
• The tMap variables (see next recipe)
• Talend supplied functions
• User supplied code routines
• Standard Custom java functions
• Included methods from JAR files

Getting ready

Open the job jo_cook_ch04_0020_usingExpressions

How to do it...

1. Open tMap.
2. Click the left mouse button on the output transactionDateTime column.
3. You will notice that the expression button looks like the following:
   
4. Click on the … button to open the Expression Builder dialogue.

   Adding a Talend function

5. The bottom-left panel lists the Categories of Talend functions. Scroll down to the TalendDate category and click the left mouse...