CODEWITHSUNDEEP
angulartypescriptrxjsoperators
Matt
Matt

Reputation: 375

How to turn an Observable of a type into an Observable of another type

I have an Angular application that uses NGRX to manage the application state. I have a selector that return me an Observable.

export const mySelector = createSelector(state, (state: IState) => state.field.array);

The Observable returned has this format: {name:string; age:number}[]

What I need to do is to turn that data format in another data format, for example {firt-name:string}. I can't understand what operator should I use.

My goal is to assign the new data to a variable, inside the subscribe, somethig like this:

myVariable: {firt-name:string};

this.store.pipe(select(mySelector))
         .pipe(//here I should transform the data format)
         .subscribe(result => {myVariable = result})

Upvotes: 2

Views: 332

Answers (1)

Josep
Josep

Reputation: 13071

You can either use map:

function mapper(data: { name: string; age: number }[]) {
  return data.map(({ name, age }) => ({
    "first-name": name,
    age
  }));
}

this.store
  .pipe(
    select(mySelector),
    map(mapper)
  )
  .subscribe(result => {
    myVariable = result;
  });

or perform that transformation in your selector:

function mapper(data: { name: string; age: number }[]) {
  return data.map(({ name, age }) => ({
    "first-name": name,
    age
  }));
}

this.store
  .pipe(
    select(
      pipe(
        mySelector,
        mapper
      )
    )
  )
  .subscribe(result => {
    myVariable = result;
  });

Upvotes: 2

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