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Calling a sling servlet from Coral3 based Select dialog field


Level 3

Hi All,

We are in the process of converting classic UI dialogs to Touch UI compatible. Whereas few of our components are having select fields (dialog item options) which are getting populated from a servlet response (JSON)

For example, in our classic UI dialog we were calling the servlet as highlighted in the below snap:


Is there any way to make use of the same servlet by calling it from some property? in Coral3 based touch UI select field? I have tried doing something like as follows, but looks like my servlet call is not happening as per logs:




fieldLabel="Choose Contacts"






Yes, I have gone through various forums and found that there are multiple ways  to achieve this. For instance:

  1. Using WCMUsePojo as explained in the following article: Building Experience Manager Components using Granite/Coral Resource Types
  2. Or even by creating a JS and calling my servlet via  ajax call under "dialog-ready" and binding the response to dom elements

My question is: Is it not feasible to call a  servlet directly from my dialog properties in case of Touch UI Coral3? or am I missing anything?

Thanks in advance for any pointers!

-Dinesh kumar L.

8 Replies


Level 10

To populate a Granite/Coral Select field dynamically - you use a DataSource object. The use of WCMUsePojo is one way to create the DataSource object:

countries.put("in", "India");

countries.put("us", "United States");

countries.put("aus", "Australia");

countries.put("pak", "Pakistan");

countries.put("sri", "Srilanka");




//Creating the Datasource Object for populating the drop-down control.

DataSource ds = new SimpleDataSource(new TransformIterator(countries.keySet().iterator(), new Transformer() {




//Transforms the input object into output object

public Object transform(Object o) {

String country = (String) o;


//Allocating memory to Map

ValueMap vm = new ValueMapDecorator(new HashMap<String, Object>());


//Populate the Map

vm.put("value", country);

vm.put("text", countries.get(country));


return new ValueMapResource(resolver, new ResourceMetadata(), "nt:unstructured", vm);

No need to create a Serlvet - your Select field can be populated via a custom resource type as shown in the doc -

Building Experience Manager Components using Granite/Coral Resource Types

Notice the datasource node is a custom resource type:

sling:resourceType (String) - /apps/Lab2018/components/datasource/mylist/mylist.html (this value points to the JCR node where the HTL script is located. The HTL gets the DataSource object defined in the HtlDataSourceExample Java class. )


Level 3

Hi Smacdonald,

Thanks for your quick reply. Yes I have gone through the reference URL which you shared. Is there anyway the below kind of property can help in achieving the same?


I tried the above, but it did not work for me in Coral3. Reason why I am looking for the above approach is, we have almost 15+ such servlets in total across components. If it works, then I dont have to do lot of coding during my Classic to Touch UI dialog conversion activity.


Level 10

Since the creation of granite - the best practice to populate a Select field dynamically is to use a DataSource object.

We have older community article - 6.2 - that shows how to use a JSP to perform this too: Adobe Experience Manager Help | Using Granite DataSource objects to populate Experience Manager 6.2 ...

A 6.3 article - Adobe Experience Manager Help | Using an WCMUsePojo class to populate an Experience Manager Touch UI...

Both show use of com.adobe.granite.ui.components.ds.DataSource object

A Servlet was used in Classic UI - but for Touch UI - it would be best practice to convert to use DataSource.


Community Advisor

You can use servlet(datasource) and give add options property as a json file path. Read Josn content and return parsed JSON to create dropdown options.

Example - aem63app-repo/DatasourceJson.java at master · arunpatidar02/aem63app-repo · GitHub

Arun Patidar


Level 10

Excellent example Arun! As i said in my original response - the key is using a DataSource object and use of WCMUsePojo is but 1 way to implement it.

Arun - if you want - we can make a note of your example in article and reference your Github. Let me know.


Community Advisor

HI Scott,

Its fine, please go ahead for article.

Screenshot 2018-10-16 at 9.54.08 PM.png

JOSN formate for this above code example:








Arun Patidar


Level 3

Based on your pointers, it is pretty clear that we have to either alter all our servlet classes or should convert them as a child class of WCMUsePojo which returns com.adobe.granite.ui.components.ds.DataSource object. Because our servlets return JSON string object (org.apache.sling.commons.json.JSONObject converted to String) in Classic UI dialog.

Thanks Arun and Scott for your quick replies!!


Level 10

Correct - it does not matter if you call a Servlet or use a resource type that points to WCMUsePojo - the key is to use a DataSource Object. In your Java code - you can parse you JSON and set the MAP used to create a DataSource object - that will work.