Return from inside an observable

Question

I'm think fundamentally i'm doing something wrong. I'm trying to find a single entity by pulling it from filtered list, if there isn't an entity there I need to create one.

I feel like this function is wrong because I should be returning an observable but instead returning nothing

getOrCreateNew(receiverId: number) : Observable<Conversation> {
    var userId = this.identity.userInfo.id;

    //TODO: you should be using an expression here, and having a builder for generating your
    //filters in case you want to switch them in the future
    var employerFilter = new PropertyFilterNode("EmployerUserId", FilterCondition.Equal, receiverId.toString());
    var employeeFilter = new PropertyFilterNode("EmployeeUserId", FilterCondition.Equal, userId.toString());
    let conversationFilter = new BinaryFilterNode(employerFilter, employeeFilter, Combiner.Or);

    this.getList(conversationFilter).subscribe(entities => {
        if (entities == null || entities.length == 0) {
            let conversation: Conversation;
            conversation.employerUserId = receiverId;
            conversation.employeeUserId = userId;
            return this.create(conversation);
        }
        else {
            let entity = entities[0];
            return Observable.of(entity); //.Return(entity)
        }
    });

    return null;
}

How can I return an observable which is return from inside subscribe?

Answer 1

The way getList subscription works suggests that it is supposed to be mergeMap or switchMap (considering that create returns an observable as well):

return this.getList(conversationFilter).mergeMap(entities => {
    if (entities == null || entities.length == 0) {
        let conversation: Conversation;
        conversation.employerUserId = receiverId;
        conversation.employeeUserId = userId;
        return this.create(conversation);
    }
    else {
        let entity = entities[0];
        return Observable.of(entity); //.Return(entity)
    }
});

In this case an observable that is returned from getOrCreateNew should be subscribed in order to emit values because it isn't subscribed internally.

Answer 2

Place the return before this.getList also :

return this.getList(conversationFilter).subscribe(entities => {