The message binding is a "GroovyMessage" object. The GroovMessage class is a convenience class that wraps the standard GatewayMessage class, which in turn wraps json object. The message object is not a map, and fields cannot be accessed using the Groovy dot notation for getters. In order to use the map notation, use asMap() as follows:

messageMap=message.asMap()
messageMap.incident.description

Tip: to avoid null pointer exceptions in Groovy, you can use “Safe navigation”:

messageMap.incident?.description

In this case, if the message does not contain a structure called “incident”, the expression returns null instead of throwing an exception. In combination with the Groovy Elvis operator, this can be used to assign a default value like this:

def description = messageMap.incident?.description :? "A default description"

For more detail see http://www.groovy-lang.org/operators.html#_safe_navigation_operator

To access the message directly, use get and put with the slash notation:

message.get("incident/description")
message.put("incident/description","The crossbeam has gone out of skew on the treddle")

Iterating over message content

There are two ways of iterating over a message: using a regular expression in the “from” field of a mapping, or using the Groovy “each()” method on the map representation of the message. The examples in this section use a Groovy poller that retrieves data from the WHO listing average life expectancy by country:

http=option.http
ret=http.get("https://apps.who.int/gho/athena/api/GHO/WHOSIS_000001?format=json")
api.publish(ret,"WhoMessage",false)
return null

Using a regular expression

When you define a mapping with a regular expression and a capture group in the “from” field, the mapping will be executed once for each matching result, automatically iterating over the result set. In the mapping itself, the content of the current branch (the part of the message referenced by the matching from field) is made available as “curnode”. In this example, we basically add a country code lookup table to the message.

Using Groovy each() 

message.asMap().dimension.each() { dim ->
    dim.code.each() { code ->
        message.put("Lookup/"+dim.label.textValue()+ "/" + code.label.textValue(),code.display.textValue())
    }
}

In this second example, there are two nested iterations to create a lookup table not just for countries, but for all dimensions of the data. 

CAUTION: The iterator function each() only works on arrays. If a certain part of the message should be an array but isn’t, you can easily convert it into an array by using the “Convert object node to array” mapping before processing it in Groovy.

CAUTION: The closure parameter of the each() operator (dim and code in the example) represent Jackson JsonNode objects. To turn them into scalar values, use the textValue(), intValue() or doubleValue() methods.

Another example of Groovy each() 

In the following example we poll a URL to search for issues from Jira. For each ticket we get the issue details by getting each issue individually.

// search for tickets 
query = "updated>='"+lasttime+"' AND project=TEST order by updated ASC"
query = java.net.URLEncoder.encode(query, "UTF-8")
url = "https://faciligate.atlassian.net/rest/api/2/search?jql=" + query
option.http.content("application/json")
option.http.useAuth("jira")

ticketsres=option.http.get(url)

// parse the response as messages 
msgs = api.parse(ticketsres,msgtype, true)

// iterate over messages 
msgs.extractMessages().each() { m -> 
    // set message id to GET the message 
    m.headers().set("idlocation","key") 
    url = "https://faciligate.atlassian.net/rest/api/2/issue/" + m.getId()
    extendedTicketStr=option.http.get(url)
    resMap = parser.asMap(extendedTicketStr)

    // parse the response as message 
    msg = api.parse(parser.asJson(resMap),msgtype, false)
    // publish each mesage 
    api.publish(msg)
}

Headers

The following headers can be manipulated using message.headers().set(headername,value). You can also read the current header value using message.headers().headername