groovy

Runs a user-defined Groovy script to process input records. Specify the name of a Groovy script deployed on the server, and the script's onRow() method is called for each record.

Command properties

Syntax

Target

SCRIPT_NAME

The name of the Groovy script to run. Loads the SCRIPT_NAME.groovy file stored in the query_scripts/ directory. The script must extend the GroovyQueryScript abstract class and implement the onRow() method.

Error codes

Parsing errors

Runtime errors

N/A

Description

The groovy command loads and runs a Groovy script deployed in the query_scripts/ directory. The script must extend the GroovyQueryScript abstract class. Override the onRow(Row row) method to process input records. Call pipe.onRow(row) to pass a processed record to the next command.

If the script implements the ThreadSafe interface, it runs in parallel without synchronization. Otherwise, execution is serialized using a synchronized block.

The script lifecycle methods are:

• onStart(): Called once when the query starts.
• onRow(Row row): Called for each input record.
• onRowBatch(RowBatch rowBatch): Called for each batch of records. The default implementation calls onRow() for each record in the batch.
• onClose(): Called once when the query ends.

Examples

1. Run a Groovy script

   json "[{'msg': 'Hello'}, {'msg': 'World'}]"
   | groovy my_transform
   

   Loads the query_scripts/my_transform.groovy script and processes each record.

2. Groovy script example

   The following is an example of query_scripts/add_length.groovy. It calculates the length of the msg field and assigns it to the msg_len field.

   import org.araqne.logdb.groovy.GroovyQueryScript
   import org.araqne.logdb.Row
   
   class AddLength extends GroovyQueryScript {
       void onRow(Row row) {
           def msg = row.get("msg")
           if (msg != null)
               row.put("msg_len", msg.toString().length())
           pipe.onRow(row)
       }
   }
   

   After deploying this script, run it as follows.

   json "[{'msg': 'Hello'}, {'msg': 'World'}]"
   | groovy add_length
   

   A msg_len field is added to each record.