The User Defined Java Class Step


Today I would like to talk about the “User Defined Java Class” a.k.a. UDJC step introduced in Kettle 4.0. This step is incredibly versatile. It allows you to put arbitrary processing code into the ETL without the penalty of a performance hit. This article shows how to use the step in different scenarios, explaining each of . . . → Read More: The User Defined Java Class Step

Generating Rows using JavaScript in Pentaho Kettle

Generate Rows Preview

If you have read the article about using Java code in Kettle, you might be wondering whether it is possible to generate rows using the Modified JavaScript Value step in a Kettle transformation. In other words, whether you could use JavaScript to create a step, which generates rows just as the table input step and the Excel input step do.  Well, it is possible. For purposes of illustration let’s create a short example that will output all of our Java system properties as rows. Download the example transformation if you like.

First things first. The Modified JavaScript Value step is not an input step as such, and will not execute without receiving some input first. Fortunately it is easy to create a single empty row using the Generate Rows input step. Just leave all fields empty and limit the output to only one row. If we connect this to a JavaScript step, it will start executing.

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