To check item in list Firebase

[rafaelmoura]

How to check if one item is in the list of firebase before to save him?

In my component my code is

this.voteService.save(cpf, 'CPFS')

My service I have

  saveCPF(path: string) {
    return this.db.list(this.PATH + path)
      .snapshotChanges()
      .map(changes => {
        return changes.map(c => ( {key: c.key , ...c.payload.val() } ));
      })
  }

here I would like to know if item CPF is in list firebase
ex:

if(firebase.list != null) {
  if(firebase.list.item == item) {
    console.log('item already in list')
  } else {
    console.log('save success')
  }
} else {
  console.log('not exist list')
}