Issue
I have an event which call 3 http observable. order of these request is important to me. so I have to use concat from rxjs. for example with the first request I got the data and fill my local variable values with that, then I want to check if the result of one of those local variable is true then send next request. something like that:
onMyEvent(e){
let isRoundingAdditionIsRequiered = false;
let ishavePeriodicalDiscount = false;
const api = 'api/Sales/SaleTemplate/' + e;
const firstApiGet = this.dataSourceService.generateCustomApiDataList(
'sales',
'SaleTemplate',
api
).dataList$;
const secondApi= 'api/Sales/Addition/List?$filter=AdditionCode eq "4"'
const secondApiGet= this.dataSourceService.generateCustomApiDataList(
'sales',
'SaleTemplate',
api
).dataList$;
const postApi =
'api/Sales/Contract/CalculateAllRowPrices/';
const calculatePrice=
this.dataSourceService.generateCustomApiPost
('sales','Contract',postApi,this.entity).dataList$;
}
now by the result of firstApiGet
I want to set isRoundingAdditionIsRequiered
to true
. like this:
firstApiGet.subscribe(data => { if (data.RoundingAdditionIsRequiered) {isRoundingAdditionIsRequiered =true} });
then check it for next request:
if (isRoundingAdditionIsRequiered ){
secoundApi.subscribe(data => {// codes here ...})
}
// and other codes ...
this is not work sequential so I have to use concat operator.
somthing like concat(firstApiGet,secondApiGet,postApi).subscribe(data=>{//...})
so what is the code?
Solution
You can use switchMap
operator.
onMyEvent(e) {
let isRoundingAdditionIsRequiered = false;
let ishavePeriodicalDiscount = false;
const api = 'api/Sales/SaleTemplate/' + e;
const firstApiGet = this.dataSourceService.generateCustomApiDataList(
'sales', 'SaleTemplate', api ).dataList$;
const secondApi= 'api/Sales/Addition/List?$filter=AdditionCode eq "4"'
const secondApiGet= this.dataSourceService.generateCustomApiDataList(
'sales', 'SaleTemplate', api ).dataList$;
const postApi = 'api/Sales/Contract/CalculateAllRowPrices/';
const calculatePrice= this.dataSourceService.generateCustomApiPost(
'sales','Contract',postApi,this.entity).dataList$;
}
firstApiGet.pipe(
switchMap( data => {
isRoundingAdditionIsRequiered = data.RoundingAdditionIsRequiered;
return isRoundingAdditionIsRequiered ? secondApiGet : of( undefined );
),
switchMap( () => calculatePrice )
).subscribe();
}