I just fetched some raw data from a server and after that I need to parse the data before I render them on a component.
So where should I put the code to parse data? In the reducer or in the action? I think it should be put in reducer, but is that suitable?
You should be dispatching an action that kicks off a request to the server for the information you need. This can be done using either sagas or thunks. Both are good solutions. Send the request in the thunk or saga and handle the response in the thunk or saga. The response handler should do whatever processing is necessary on the data and then should dispatch another action to update the redux store with the new data.