Angular2 Observable, subscribe and map. Communication

Question

I have issue with Observables. I have no trouble with basic communication e.g.: SERVICE:

getTableRecords(): Observable<RecordModel[]> {
        return this.http
            .get( this.API + 'records' )
            .map( (tableRecords: Response) =>  tableRecords.json().data as RecordModel[] )
            .catch(this.handleError);

    }

COMPONENT:

getTableRecords() {
        this.recordService.getTableRecords()
            .subscribe( tableRecords => { this.tableRecords = tableRecords; }, (err) => { this.error = err; console.log(this.error)})
    }

Example on top works well, but I have issue with one extra step. Before I'll display result, I wannt to filter one value based on parametr with communications between two services:

SERVICE I:

getTableRecords(): Observable<RecordModel[]> {
        return this.http
            .get( this.API + 'records' )
            .map( (res: Response) =>  res.json().data as RecordModel[] )
            .catch(this.handleError);

    }

SERVICE II

getRecordDetail(assetId: string) {
        return this.rootService.getTableRecords()
            .map( (tableRecords:RecordModel[]) => {
                console.log("GET RECORDS TO ANOTHER SERVICE: ", tableRecords, assetId);
                (tableRecords:RecordModel[]) => tableRecords.filter( (tableRecord:RecordModel) => tableRecord.assetId === assetId )
            })
    }

COMPONENT:

tableRecord: RecordModel;

getRecordDetail() {
        this.sub = this.activatedRoute.params.subscribe(
            params => {
                if (params[ 'assetId' ] != undefined) {
                    let assetId:string = params[ 'assetId' ]
                   this.complianceDetailService.getRecordDetail(assetId)
                        .subscribe( result => this.tableRecord = result )
                } else console.log("UNDEFINED ASSETID");
            }
        );
    }

In COMPONENT I have issue in .subscribe( result => this.tableRecord = result ) IDE yells that void is not assignable to type RecordModel.

Please explain I can make this sequence: First: Get data from one service, Two: Manipulate data in second service, Three: return data to component.

All of this I want to make with Observables, because same sequence I am able to make with Promises.

Best Regards Uland!

raj · Accepted Answer · 2017-01-24 10:58:24Z

1

getRecordDetail(assetId: string) {
        return this.rootService.getTableRecords()
            .map( (tableRecords:RecordModel[]) => {
                console.log("GET RECORDS TO ANOTHER SERVICE: ", tableRecords, assetId);
                return  tableRecords.filter( (tableRecord:RecordModel) => tableRecord.assetId === assetId )
            })
    }

edited Jan 24, 2017 at 10:58

answered Jan 24, 2017 at 10:45

raj

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1 Comment

Uland Nimblehoof Over a year ago

Thanks for answer, but unfortunately If I make it that way, in IDE I got err: [ts] The type argument for type parameter 'T' cannot be inferred from the usage. Consider specifying the type arguments explicitly. Type argument candidate 'RecordModel[]' is not a valid type argument because it is not a supertype of candidate 'RecordModel'. Property 'length' is missing in type 'RecordModel'. this: this

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