How to retrieve query parameters in WSO2 ESB

There are several ways to retrieve query parameters from an HTTP request using WSO2 ESB.

• Using Synapse XPath $url variable
• Using get-property(‘query.param.xxx’)

We can use the following curl GET request for the following sample API

$ curl “http://localhost:8280/store/view?name=john&age=29” -v

Using Synapse $url XPath variable

There is an XPath variable $url which we can use to retrieve query parameters from an HTTP request.

<property name=”name” expression=”$url:name” type=”STRING”/>

Following is an example using the $url. Note that you don’t have to mention the query params in the uri-template

Using get-property(‘query.param.xxx’)

Another option is to use the get-property function with argument as query.param. where **value** is the relevant name of the query parameter

get-property(‘query.param.name’)

Example API with get-property function

Sample curl rquest and response

$ curl “http://localhost:8280/store/view?name=john&age=29” -v

*   Trying 127.0.0.1...
* Connected to localhost (127.0.0.1) port 8280 (#0)
> GET /store/view?name=john&age=29 HTTP/1.1
> Host: localhost:8280
> User-Agent: curl/7.50.1
> Accept: */*
> 
< HTTP/1.1 200 OK
< Accept: */*
< Host: localhost:8280
< Content-Type: application/x-www-form-urlencoded; charset=UTF-8
< Date: Sun, 13 Aug 2017 14:40:01 GMT
< Transfer-Encoding: chunked
< 
* Connection #0 to host localhost left intact
<user><name>john</name><age>29</age></user>

You can test this out with WSO2 Integrator which is the WSO2 ESB product packaged with other integration products like WSO2 Message Broker, WSO2 Business Process Engine and WSO2 Data Services Server.

Cheers!

Written by Asitha Nanayakkara