My Lookup

This example shows a customizable Lookup component, allowing you to modify the default behavior of looking up data. By leveraging the given class, you can implement your own specialized data-lookup logic tailored to specific use cases and requirements.

Lookup searches for data in another source to merge with each record passing through this lookup's transformer -- the streaming version of a join.

More information about the usage of MyLookup can be found in Write My Own Lookup.

Java Code Listing

package com.northconcepts.datapipeline.examples.cookbook.customization;

import com.northconcepts.datapipeline.core.Field;
import com.northconcepts.datapipeline.core.Record;
import com.northconcepts.datapipeline.core.RecordList;
import com.northconcepts.datapipeline.transform.lookup.Lookup;

public class MyLookup extends Lookup {
	
    public RecordList get(Object ... keys) {
        if (keys == null || keys.length != 1) {
            return null;
        }
        
        Record record = new Record();
        Field ratingClass = record.addField().setName("ratingClass");
        
        char rating = keys[0].toString().charAt(0);
        
        switch (rating) {
        case 'A': ratingClass.setValue("Class A"); break;           
        case 'B': ratingClass.setValue("Class B"); break;           
        case 'C': ratingClass.setValue("Class C"); break;           
        default: return null;           
        }
        
        RecordList list = new RecordList();
        list.add(record);
        return list;
    }

}

Code Walkthrough

1. This class extends the abstract class Lookup.
2. The abstract method get(Object... keys) should be overridden to implement custom logic for looking up data. 
3. In the given example, the Rating column is given as an input lookup field and based on its values, a new ratingClass field is added to each record.