Invoking REST Services from Gadgets

In the previous post we have seen how to write a gadget with static content. In this one, we will have a look at creating a gadget with dynamic content or the data that is coming from the JIRA server.

JIRA uses REST services to communicate between the gadgets and the server. We will see how to write REST services in the coming chapters. In this recipe, we will use an existing REST service.

Let us consider a simple modification to the Hello Gadget created in the previous tutorial to understand the basics of invoking REST services from gadgets. We will try to greet the current user by retrieving the user details from the server instead of displaying the static text: Hello From JTricks.

JIRA ships with some inbuilt REST methods one of which is to retrieve the details of the current user. The method can be reached in the URL: /rest/gadget/1.0/currentUser. We will use this method to retrieve the current user’s full name and then display it in the Gadget greeting. If the user’s name is Jobin Kuruvilla, the gadget will display the message as Hello, Jobin Kuruvilla.

Since we are only changing the content of the gadget, the only modification is required in the gadget XML which is hello-gadget.xml in our example. Only the Content element needs to be modified which will now invoke the REST service and render the content.

We first need to include the common Atlassian Gadget resources.

#requireResource("com.atlassian.jira.gadgets:common")
#includeResources()

#requireResource will bring in the JIRA Gadget Javascript framework in to the gadget’s context. #includeResources will write out the HTML tags for the resource in place. You will find more details in the link above.

Now we need to construct a Gadget object as shown below:

var gadget = AJS.Gadget

The Gadget object has 4 top level options.

• baseUrl: An option to pass the base URL. It is a mandatory option and we use __ATLASSIAN_BASE_URL__  here which will be rendered as JIRA’s base URL.
• useOauth: An optional parameter. Used to configure the type of authentication which must be a URL.  /rest/gadget/1.0/currentUser is commonly used.
• config: Another optional parameter. Only used if there are any configuration options for the gadget.
• view: Used to define the gadget’s view.

In our example, we don’t use authentication or any configuration options. We will just go with the baseUrl and view options. Following is how the Gadget is created in the javascript.

<script >
    (function () {
        var gadget = AJS.Gadget({
            baseUrl: "__ATLASSIAN_BASE_URL__",
            view: {
                ................
            }
        });
    })();
</script>

Now we need to populate the gadget view. The view object has the following properties.

• enableReload: Optional. Used to reload the gadget at regular intervals.
• onResizeReload: Optional. Used to reload the gadget when browser is resized.
• onResizeAdjustHeight: Optional and used along with the dynamic-height feature. This will adjust the gadget height when the browser is resized.
• template: Creates the actual view
• args: An array of objects or function that returns an array of objects. It has 2 attributes. Key –used to access the data from within the template and ajaxOptions – set of request options used to connect to server and retrieve data.
  

In our example, we will use the template and args properties to render the view. First let us see args because we use the data retrieved here in the template. args will look like the following:

args: [{
    key: "user",
    ajaxOptions: function() {
        return {
            url: "/rest/gadget/1.0/currentUser"
        };
    }
}]

As you can see, we invoke the /rest/gadget/1.0/currentUser method and use the key user to refer the data we retrieved while rendering the view.     ajaxOptions uses the jQuery Ajax Options details of which can be found at http://api.jquery.com/jQuery.ajax#options .

The key user will now hold the user details from the REST method as follows:

{"username":"jobinkk","fullName":"Jobin Kuruvilla","email":"jobinkk@gmail.com"}

The template function will now use this args and its key, user to render the view as follows:

template: function(args) {
    var gadget = this;
             
    var userDetails = AJS.$("<h1/>").text("Hello, "+args.user["fullName"]);         
    gadget.getView().html(userDetails);
}
   
Here args.user["fullName"] will retrieve the user’s fullName from the REST output. username or email can be retrieved in similar fashion.

AJS.$ will construct the view as <h1>Hello, Jobin Kuruvilla</h1> where Jobin Kuruvilla is the fullName retrieved.

The entire Content section will look like this:

<Content view="profile">
    <![CDATA[
        #requireResource("com.atlassian.jira.gadgets:common")
            #includeResources()
     
            <script >
        (function () {
                var gadget = AJS.Gadget({
                    baseUrl: "__ATLASSIAN_BASE_URL__",
                    view: {
                    template: function(args) {
                        var gadget = this;             
                        var userDetails = AJS.$("<h1/>").text("Hello, "+args.user["fullName"]);             
                        gadget.getView().html(userDetails);
                        },
                        args: [{
                        key: "user",
                        ajaxOptions: function() {
                            return {
                                url: "/rest/gadget/1.0/currentUser"
                            };
                        }
                        }]
                }
                });
        })();
            </script>
        ]]>
</Content>

All that is left now is to package the gadget and deploy it. Once the plugin is deployed and gadget added to dashboard, it will appear as follows:

A round of applause please...

gadget-extended-plugin.zip
File Size:	20 kb
File Type:	zip

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