Rxjs get distinct values of property value in array

Question

I am trying to get distinct values of a property in an observable array.

  let pt$ = Observable.of([{planTypeID : 1, description : 'test 1'}, 
                                {planTypeID : 2, description : 'test 2'}]);
    let planTypeIDs$ = pt$
        .flatMap(a => a)
        .map(a => a.planTypeID).distinct().toArray();

Is this the right way to do it in rxjs, or is there a better way?

Alx · Accepted Answer · 2018-07-11 14:56:39Z

1

You could use .from instead of .of, that should spare you the .flatMap
distinct will check the reference by default, so if you want to compare for contents you should create some kind of hash or make a custom comparer - but maybe that's not required here.

let pt$ = Observable.from([{planTypeID : 1, description : 'test 1'}, 
                            {planTypeID : 2, description : 'test 2'}]);
let planTypeIDs$ = pt$
    .map(a => a.planTypeID)
    .distinct()
    .toArray();

edited Jul 11, 2018 at 14:56

Alx

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answered Jan 31, 2017 at 16:06

Olaf Horstmann

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2 Comments

Yousuf Over a year ago

I am doing Observable.Of to mimic the code that I have in my project. In the project I am working on, I have a service that uses combinelatest to merge multiple observable array's and return a new array.

Olaf Horstmann Over a year ago

Okay - well it's difficult to optimize code that is not visible here ;-) - but then your current solution looks pretty much okay i guess

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