将rxjs 5映射转换为rxjs 6映射

Question

Consider the following code Angular 5 + older rxjs

this.measurementUnitsService.GetAll().subscribe(
        res => {
            this.measurementUnits = res.map(x => new MeasurementUnit(x));
        }
    )

I am getting a list of objects and for each one of them creating a new strongly typed class.

How would I go about doing the same in angular 6 + rxjs 6 My attempt.

this.measurementUnitsService.GetAll().pipe<MeasurementUnit[]>(mergeMap(x => new MeasurementUnit(x))).subscribe(
  res => {
    this.measurementUnits = res;
  }
)

It generates an error unfortunately Type 'MeasurementUnit[]' has no properties in common with type 'Partial<MeasurementUnit>'.

MeasurementUnit just in case

export class MeasurementUnit {
Id: number;
CreatedDate: Date;
ModifiedDate: Date;
Disabled: boolean;
DisabledDate: Date;
Name: string;
Description: string;

ParentId: number;

public constructor(item: Partial<MeasurementUnit>) {
    //item.EstablishedDate = new DatePipe('en-US').transform(item.EstablishedDate, "yyyy-MM-dd");

    Object.assign(this, item);
}
}

Answer 1

You have an Observable<MeasurementUnit[]> not an Observable<MeasurementUnit> .

This means, that when the observable emits a value it will be an array not a single value. Hence, you need the normal array map, not the Observable one.

Just do:

this.measurementUnitsService.GetAll()
  .pipe(
    map(array => array.map(x => new MeasurementUnit(x)))
  ).subscribe(res => this.measurementUnits = res);