Mule: Convert XML to JSON with with some of the single element in XML as array in JSON

Question

The contract with the client is to send JSON payload in rest web service call. In my Mule flow, I process XML and before doing web service call, convert it into JSON using

<json:xml-to-json-transformer>

which was working fine barring couple of issues. One of that is in XSD an element is defined with maxOccurs="5", but most of the time this element occurs in XML only 1 time. So the problem is:

When an array has more than 1 entry, it is serialized correctly
When the array has only 1 entry, it is serialized not as an array, but as a single dictionary.

So, for this XML:

<team>
 <employee>
  <name>Joe</name>
  <surname>Bloggs</surname>
 </employee>
 <employee>
  <name>Jane</name>
  <surname>Doe</surname>
 </employee>
</team>

JSON is:

{
team:{
 employee:[
  {
    name:'Joe',
    surname:'Bloggs'
  },
  {
    name:'Jane',
    surname:'Doe'
   }
  ]
 }
}

but for this XML

<team>
 <employee>
  <name>Joe</name>
  <surname>Bloggs</surname>
 </employee>
</team>

the JSON produced is:

{
  team:{
    employee:{
      name:'Joe',
      surname:'Bloggs'
    }
  }
}

The problem here is that client expects the value of employee to be an array (which it isn’t), violating the contract.

I read with the custom-transformer and Object Mapper, may be there is a way to specify which single element in XML should be forced to array in JSON or inject XSD. Is there a way?

SriniD · Accepted Answer · 2014-05-28 18:49:57Z

1

Unfortunately there is no direct way of telling the JSON XML to JSON transformer to treat the element as an Array.

There are two options:

1. Implement a custom JSON transformer of Jackson and use the Force Array option. Please refer to the Jackson webpages for more detials.

2. If possible convert your XML to Java Object. 
The object will definitely would have defined the elements as an array or colelction.
Then convert the object to JSON which would be the final expected result of sinngle element as Array in JSON.


 <mulexml:jaxb-xml-to-object-transformer name="XmlToObject" jaxbContext-ref="JAXBContext" returnClass="java.lang.Object"/>
 <json:object-to-json-transformer doc:name="Object to JSON"/>

Hope this helps.

answered May 28, 2014 at 18:49

SriniD

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2 Comments

Charu Khurana Over a year ago

Using the Force Array option, how would it differentiate the element with single value which needs to convert to array versus which do not?

SriniD Over a year ago

Even I got the same question, but haven't looked into that option in-depth. Give it a try. Option two is what I have executed and verfiied that it works.

Yevgeniy · Accepted Answer · 2017-04-22 13:27:24Z

1

here is a different approach using dataweave.

%dw 1.0
%output application/json
---
{
    team: {
        employee: payload.team.*employee default []
    }
}

result is a employee attribute, wich always contains a list.

for default [] to work you must specify the reader configuration like this:

<dw:transform-message metadata:id="06021518-b51d-4dbf-983d-b47ed5ffd0bc" doc:name="Transform Message">
    <dw:input-payload doc:sample="team.xml" mimeType="application/xml">
        <dw:reader-property name="nullValueOn" value="blank"/>
    </dw:input-payload>
    <dw:set-payload><!-- content of dataweave left out --></dw:set-payload>
</dw:transform-message>

answered Apr 22, 2017 at 13:27

Yevgeniy

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Comments

goodman · Accepted Answer · 2017-04-21 21:23:27Z

0

I implemented this by adding an attribute to the element that needs to be treated as array and handling this by writing a custom Jackson transformer by extending the

Blockquote com.fasterxml.jackson.databind.deser.std.UntypedObjectDeserializer .

Hope this helps anyone trying to achieve this.

answered Apr 21, 2017 at 21:23

goodman

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