ngOnInit() {
this.GuiaService.getGuias()
  .snapshotChanges()
  .subscribe(item => {
    this.guiaList = [];
    item.forEach(element => {
      let guia = element.payload.toJSON();
      guia["$key"] = element.key;
      this.guiaList.push(guia as Guia);
 console.log(guia)

    });
  });