What is the difference between data action and  aggregate
Question

I am using the step wizard form, and after clicking previous button my selected city data gone  When I am trying to fetch city according to stateId using aggregate its not working but with the help of data action its working properly why?

BlocksExercise.oml

Hi Megha,

I saw you oml and you need to use OnParameter changed event for block so whenever parameter change data will change as well.

You are using this aggregate as OnlyOndemand.


go with this link-

https://success.outsystems.com/Documentation/11/Developing_an_Application/Implement_Application_Logic/Actions_in_Reactive_Web_and_Mobile_Apps?_gl=1*468vxs*_ga*ODg0MDk2MjgzLjE2NDc0MTQ4NTI.*_ga_ZD4DTMHWR2*MTY0NzQxNDg1MS4xLjEuMTY0NzQxNjM1MS41Ng..


I am using on demand because according to country , I want the state and according to state I want city in a single web block, so if I will use  On Parameter changed event for block, it will not work in my case. But thanks for your support.  

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