javascript - Angular4, update component on route change -


how update component when route changes. have component :

import { component, oninit } '@angular/core'; import { activatedroute } '@angular/router'; import { listservice } '../list/list.service';  @component({   selector: 'view',   template: `     <div *ngif="!entity">     <p>select <b (click)="showrow()">row {{entity}}</b>!</p>     </div>     <div *ngif="entity">        <p >{{entity.id}}</p>       <p >{{entity.name}}</p>       <p >{{entity.weight}}</p>       <p >{{entity.symbol}}</p>     </div>   `,   styles: [] }) export class viewcomponent implements oninit {    constructor(     private route: activatedroute,     private service: listservice   ) {     this.route.params.subscribe(params => {       const id = parseint(params['id']);       if (id) {         const entity = this.service.getrow(id);         this.entity = entity       }     });   }    entity;    showrow() {     console.log(this.entity);   }    ngoninit() {   } }

in this.entity inside constructor have desired object when execute showrow this.entity undefined, i'm doing wrong ? have tried change property different name, , didn't work expected, if 1 knows how resolve or point me right direction.

edit: getrow service

getrow(id) {   console.log(id, 'test');   return this.datasource.find(row => row.id === id);//returns row }

move code ngoninit() method , check value or not.

  ngoninit() {     this.route.params.subscribe(params => {      const id = parseint(params['id']);      if (id) {          const entity = this.service.getrow(id);          this.entity = entity      }    });  }

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