CODEWITHSUNDEEP
rx-javarx-android
RCB
RCB

Reputation: 2263

What is the right RxJava operator to do this?

What is the right RxJava operator for the following scenario :

I want to check if I have a token stored, if not get it from the network and use it to perform another network request.

I think it should be done with and/then/when or with a combination of filter and flatMap but not sure how.

Upvotes: 1

Views: 85

Answers (2)

paul
paul

Reputation: 13471

I don't know if this is what you´re looking for, but the structured should be pretty simple

  Observable.just(getToken())
      .filter(token->Strings.isNullOrEmpty(token))
      .map(this::findNewToken)
      .cache() 
      .subscribe(token -> println("Your new Token")

Upvotes: 1

LordRaydenMK
LordRaydenMK

Reputation: 13321

There are many ways to solve this. One more general solution would be Observable.concat.

// Our sources (left as an exercise for the reader)
Observable<Data> memory = ...;  
Observable<Data> disk = ...;  
Observable<Data> network = ...;

// Retrieve the first source with data
Observable<Data> source = Observable  
  .concat(memory, disk, network)
  .first();

You will need two observables for your case. If the token exists in the local storage concat won't subscribe to the network observable. More info in the blog post.

Code sample from this blog post.

Upvotes: 2

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