Transforming http response to xml

Question

These are my first steps with Mule, so I may not understand some basic concepts.

There is a store running Prestashop, that exposes REST service.

All I want to do now, is to send request to store, get response, replace one value , and save it to a file.

The response looks like this:

<?xml version="1.0" encoding="UTF-8"?>
<prestashop xmlns:xlink="http://www.w3.org/1999/xlink">
<stock_available>
    <id><![CDATA[1]]></id>
    <id_product xlink:href="http://xxxxxxxxxxxxx/api/products/1"><![CDATA[1]]></id_product>
    <id_product_attribute><![CDATA[0]]></id_product_attribute>
    <id_shop xlink:href="http://xxxxxxxxxxxxx/api/shops/1"><![CDATA[1]]></id_shop>
    <id_shop_group><![CDATA[0]]></id_shop_group>
    <quantity><![CDATA[0]]></quantity>
    <depends_on_stock><![CDATA[0]]></depends_on_stock>
    <out_of_stock><![CDATA[2]]></out_of_stock>
</stock_available>
</prestashop>

I want to replace the value 'quantity'. For now - with a constant value. My current flow is:

<?xml version="1.0" encoding="UTF-8"?>
<mule xmlns:file="http://www.mulesoft.org/schema/mule/file" xmlns:data-mapper="http://www.mulesoft.org/schema/mule/ee/data-mapper" xmlns:http="http://www.mulesoft.org/schema/mule/http" xmlns:mulexml="http://www.mulesoft.org/schema/mule/xml" xmlns="http://www.mulesoft.org/schema/mule/core" xmlns:doc="http://www.mulesoft.org/schema/mule/documentation"
    xmlns:spring="http://www.springframework.org/schema/beans" version="EE-3.6.0"
    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
    xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans-current.xsd
http://www.mulesoft.org/schema/mule/core http://www.mulesoft.org/schema/mule/core/current/mule.xsd
http://www.mulesoft.org/schema/mule/http http://www.mulesoft.org/schema/mule/http/current/mule-http.xsd
http://www.mulesoft.org/schema/mule/xml http://www.mulesoft.org/schema/mule/xml/current/mule-xml.xsd
http://www.mulesoft.org/schema/mule/file http://www.mulesoft.org/schema/mule/file/current/mule-file.xsd
http://www.mulesoft.org/schema/mule/ee/data-mapper http://www.mulesoft.org/schema/mule/ee/data-mapper/current/mule-data-mapper.xsd">
    <http:listener-config name="HTTP_Listener_Configuration" host="0.0.0.0" port="8081" doc:name="HTTP Listener Configuration"/>
    <http:request-config name="HTTP_Request_Configuration" host="xxxxxxxxxxxxxxxx" port="80" basePath="/api/" doc:name="HTTP Request Configuration">
        <http:basic-authentication username="xxxxxxxxxxxxxxxxxxxxxxx" password="x"/>
        <http:raml-api-configuration location="api.raml"/>
    </http:request-config>
    <flow name="1Flow">
        <http:listener config-ref="HTTP_Listener_Configuration" path="/" doc:name="HTTP"/>
        <http:request config-ref="HTTP_Request_Configuration" path="/stock_availables/{id}" method="GET" doc:name="HTTP">
            <http:request-builder>
                <http:uri-param paramName="id" value="#[message.inboundProperties.'http.query.params'.id]"/>
            </http:request-builder>
        </http:request>
        <byte-array-to-object-transformer doc:name="Byte Array to Object" mimeType="text/xml"/>
        <mulexml:object-to-xml-transformer doc:name="Object to XML"/>
        <file:outbound-endpoint path="C:\test" outputPattern="test.txt" responseTimeout="10000" doc:name="File"/>
    </flow>
</mule>

This already connecting to a service, gets response and saves file. BUT I don't know, how to modify it's content.

One of problem, that I cannot understand is: When I look into debugger, after "Byte Array To Object", the payload has type java.lang.string. After "Object to XML" the payload has still type java.lang.string, and the payload's value is :

<string>&lt;?xml version=&quot;1.0&quot; encoding=&quot;UTF-8&quot;?&gt;
&lt;prestashop xmlns:xlink=&quot;http://www.w3.org/1999/xlink&quot;&gt;
&lt;stock_available&gt;..............blahblahblah.........</string>

When I try to use xslt transform it results with error.

How to modify that value?

Answer 1

You have a couple options here. First off your http transport will return you a byte array which you can then transform to a String using the byte array to string transformer. After that you can either call a custom processor and transform the string payload in the java code or try some combination of the regex function inside MEL (#[regex()]) and the string appender transformer to transform the payload completely within the mule xml code.

Answer 2

You can get all values from the response xml via xpath. Look into Example 5 in following link http://www.mulesoft.org/documentation/display/current/Mule+Expression+Language+Examples

Answer 3

I am trying to give you an overview on the direction which you could take, not necessarily to give you a direct solutions, sorry for that!

The keyword which describes what you need to introduce a "Message Processor" in your, more specifically a Transformer.

The Transformer will receive your XML, will make the desired adjustments to it and will give the modified XML to the output, in your case to the File endpoint.

For example, you could write the transformer in form of a POJO. You send it your XML as a String. You Java class with have a method which does the processing and returns the modified String (aka your desired XML).

To get a String, you should use the transformer Byte-Array-to-String.