Converting with custom transformer

1. Transforming with Custom
Transformer in Mule

2. Sometime in our Mule flow we require to transform a
payload from one form to another.
For example in some cases, we need transform an XML
payload to JSON

3. Now there are several ways of transforming the XML payload to
JSON in Mule. You can use XML to Object transformer and then
Object to JSON transformer in doing so.
But how about using a custom transformer to directly transform
XML to JSON ?
It will be a very easy way in achieving that without using much
transformer in our flow and can directly transform end-to-end

4. But how can we use Custom transformer to transform in
Mule??
.

5. Here I will show you how ……

6. Let us consider we have a following Mule flow :-
Now you can see in the above flow the inbound endpoint will pic a file that
contains XML content from a location and put it into another location and the
outbound file will contain it’s corresponding JSON content.
You can also see a custom transformer in the middle which is responsible for
this XML payload conversion to JSON directly.

7. Now, let’s check the code for this flow :-
<flow name="CustomXMLToJSONTransformer" doc:name="CustomXMLToJSONTransformer">
<file:inbound-endpoint path="E:backuptest" responseTimeout="10000" doc:name="File">
<file:filename-regex-filter pattern="xmlFile.txt" caseSensitive="false"/>
</file:inbound-endpoint>
<file:file-to-string-transformer doc:name="File to String"/>
<custom-transformer class="CustomXMLToJSONTransformer" doc:name="XmlToJson"/>
<logger message="#[message.payload]" level="INFO" doc:name="Logger" />
<file:outbound-endpoint path="E:backuptestnewfolder" outputPattern="jsonFile.txt"
responseTimeout="10000" doc:name="File" />
</flow>
As you can see the file xmlFile.txt contains XML content that will be converted directly
into JSON by the custom-transformer into a file jsonFile.txt

8. Now let’s check the XML content of file xmlFile.txt :-
So, the above is the XML content we need to convert using our custom
transformer into a corresponding JSON

9. So our custom transformer java class is the following :-
public class CustomXMLToJSONTransformer extends AbstractMessageTransformer implements
DiscoverableTransformer {
public Object transformMessage(MuleMessage message, String outputEncoding)
throws TransformerException {
try {
String xml = (String) message.getPayload();
XmlMapper xmlMapper = new XmlMapper();
List entries = xmlMapper.readValue(xml, List.class);
ObjectMapper jsonMapper = new ObjectMapper();
String json = jsonMapper.writeValueAsString(entries);
return json;
} catch (Exception e) {
System.out.println("Error: " + e);
e.printStackTrace();
}
return null;
}
@Override
public int getPriorityWeighting() {
return 0;
}
@Override
public void setPriorityWeighting(int weighting) {
}
}

10. Now let’s test our application . We will see the following in our Mule console :-
You can see the payload is transformed into JSON and has been dispatched to location
E:backuptestnewfolder with file name jsonFile.txt

11. Now if we open the file jsonFile.txt from location
E:backuptestnewfolder we will get our JSON content as following
You can see you have generated the JSON for the XML directly just using a simple
custom transformer component

12. Hope you enjoyed the simple yet an amazing trick in Mule