Wednesday, January 16, 2019

Dynamically Populate Drop Down Values in AEM

Hello Everyone,

You must be thinking that what I am gonna talk about here if there are hundreds of blogs
available over the internet about dynamic drop down. So there are really some things which
might be new to you and this blog won't disappoint you.

There are so many places in AEM project  where we need to dynamically populate
drop down for instance populate the list of pages, populate the country list and so on.
There are two types of use cases which are being used in each and every project.
  • Dynamically populate drop down based on datasource (Build on logic)
  • Dynamically Populate drop down based on values available statically using ACS Commons Generic list. (No logic)
Dynamically Populate Drop Down Based On Datasource

Problem Statement: Let suppose I have a requirement of pulling all the children pages of a root path in drop down.
Step 1: Make a drop down widget and create a datasource node under it like this:
Fig -1 Data Source Node Under Select Widget
Step 2: Add a property “resourceType” in datasource which can be mapped to “paths” and “resourceTypes” of the servlet.
Fig -2 Add Resource Type Property In Data Source
Step3: Write a java class mapped to datasource and write a logic to dynamically populate values in the drop down.
sling:resourceType of datasource = sling.servlet.paths of servlet
sling:resourceType of datasource = sling.servlet.resourceTypes of servlet

Note: I have seen people writing a new servlet for every select but actually this is not required. We can get more control on the component if multiple select can use the same service.To make this point clear read the problem statements below and understood how we can solve this.
Let’s discuss few more problem statements:
  • In a project there can be situations where in a component A, you want to pull drop down from Root X and in the component B, you want to pull drop down from Root Y.
Solution: you can add a property may be rootPath in datasource node and fetch the value of that rootPath in the servet and show values.
  • There can be a situation that in component A you want to pull list of pages but in component B you want to pull list of countries.
Solution: You can add a property may be selector as “pageListing” for fetching all the pages or “countryList” to fetch all the countries list and in the servlet call different functions to dynamically populate different values.
Fig -4

Check the code for the above problem statement on github from here.
See the demo video for more visibility over all the problem statements and solutions:

Demonstration Video On How to Populate Drop Down Dynamically Based On DataSource:

Dynamically Populate Drop Down Based On Values Available Statically
Using ACS Commons Generic List

If you are working in AEM platform, you must be aware about ACS Commons and its features and here I am going to describe one feature which is Generic Lists.

Using generic lists, if you have some values and want to populate these values dynamically in drop down you can do. The benefit is if one day author want to add one more value, he can add one more value by himself.

Prerequisites: Your AEM instance must have acs commons package.
Step1: Go to misadmin and select Generic Lists under acs commons.
Step2: Click on New.
Step3: Select generic list template and click on Create.
Step4:Open the page and drag and drop a component named Generic List Item.
Fig -4 

Step5: Add the Title and Value in the Generic List Item component.
Fig -5 Generic List Items
Title: The title which will be visible to the author in drop down.
Value: Value is what gets stored corresponding to what text you selected from drop down. Now values are ready to populate in drop down component.
  • Make a drop down widget and create a datasource node.
  • Add following values in the datasource node.
Fig -6 Data Source Node for using ACS Commons Generic List 
1. sling:resourceType="acs-commons/components/utilities/genericlist/datasource"
2. path="/etc/acs-commons/lists/country-list" //This path is the page path you created earlier and added generic list item.
This is how you can dynamically populate all the values in drop down using generic lists.
Demonstration Video On How to Populate Drop Down Based on Values Available Statically Using ACS Commons Generic List:

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Hope it will help you guys !!
Thanks and Happy Learning.