CODEWITHSUNDEEP
androidjsonkotlinretrofit
Goopher
Goopher

Reputation: 147

How to combine two kotlin data objects with shared variable into one object?

I'm making a little application which tracks cryptocurrency values at the Bittrex exchange.

For this I'm using Bittrex' public api (https://bittrex.github.io/api/v3) Unfortunately the api doesn't provide the data I want with just one call, therefore I need to do two api calls.

What I want to achieve is to have one object containing all of the following values:

The bold variable is part of one api call, the other values are part of the other. 'Symbol' is part of both.

I'm using kotlin coroutines and I was hoping that I don't have to use something like RxJava to get this to work.

    CoroutineScope(IO).launch {
        val tickers = async {
            api.getTickers()
        }.await()

        val markets = async {
            api.getMarkets()
        }.await()
        val result = mutableListOf<Market>()
        for (ticker in tickers.data) {
            for (market in markets.data) {
                if (ticker.symbol == market.symbol) {
                    result.add(
                        Market(
                            ticker.symbol,
                            ticker.lastTradeRate,
                            market.quoteVolume,
                            market.percentChange
                        )
                    )
                }
            }
        }
    }

Upvotes: 0

Views: 598

Answers (1)

Francesc
Francesc

Reputation: 29260

You can make the 2 calls in parallel using coroutines.

Assuming firstApi and secondApi are suspend functions that return the data for each of the 2 blobs of info you need,

val data1Deferred = async { firstApi() }
val data2Deferred = async { secondApi() }
val data1 = data1Deferred.await()
val data2 = data2Deferred.await()
val result = Result(
    // build result from data1 and data2
)

You would also need to add error handling.

Edit:

you can group your list by the symbol and generate a map:

val marketMap = markets.associateBy { it.symbol }

Then for each ticker you can get the corresponding market

for (ticker in tickers) {
    val market = marketMap[ticker.symbol]
    if (market != null) {
        // join ticker and market
    }
}

Upvotes: 1

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