What are some methods for extracting the values of keys from an object?

I am facing an issue where I have data collected from a service in the form of an interface type object, but I am unable to find or filter a key within this object.

The specific error message I am encountering is: ERROR TypeError: Cannot read property 'userAccess' of undefined at ShowBranchuserComponent.push../src/app/pages/userrelated-page/show-branchuser/show-branchuser.component.ts.ShowBranchuserComponent.ngOnInit (show-branchuser.component.ts:42)

import { Component, OnInit } from '@angular/core';
import { ActivatedRoute, Router } from '@angular/router';
import { UserrelatedService } from '../userrelated-page.service';
import { UserRegister } from 'app/shared/model/Register';
import { FormGroup, FormControl, FormBuilder, Validators } from '@angular/forms';
import { RouteInfo } from 'app/shared/sidebar/sidebar.metadata';
import {map} from 'rxjs/operators';


@Component({
  selector: 'app-show-branchuser',
  templateUrl: './show-branchuser.component.html',
  styleUrls: ['./show-branchuser.component.scss']
})
export class ShowBranchuserComponent implements OnInit {
  showuser: UserRegister;
  pname;
  regularForm: FormGroup;
  access:RouteInfo[];

  constructor(private _AR:ActivatedRoute, 
    private _router: Router, 
    private _userRelated: UserrelatedService,
    private _fb: FormBuilder) { 
    this._AR.params.subscribe(data=>{this.pname = data['id']})
  }

  ngOnInit() {
    this._userRelated.getOneUser(this.pname).subscribe(data=> this.showuser = data);
    this.regularForm = this._fb.group({
      'id': [{value:'', disabled: true}, Validators.required],
      'name':[{value:'', disabled: true}, Validators.required],
      'username':[{value:'', disabled: true}, Validators.required],
      'role':[{value:'', disabled: true}, Validators.required],
      'status':[{value:'', disabled: true}, Validators.required],
      'state':[{value:'', disabled: true}, Validators.required],
      'pincode':[{value:'', disabled: true}, Validators.required],
      'mobileno':[{value:'', disabled: true}, Validators.required],
      'address':[{value:'', disabled: true}, Validators.required],
    });
   this.access = this.showuser.userAccess; // The problematic line triggering the error is here 
    console.log(this.showuser);
  }

  onReactiveFormSubmit(){

  }
}

Answer №1

When dealing with observable values, it's important to remember that returning them is an asynchronous operation. This means that attempting to access the value immediately may result in errors, as the value might not have been defined yet. To gain a better understanding of this concept, I recommend reading up on JavaScript's queue and the event loop.

To avoid issues with undefined values, make sure to assign showuser.userAccess to the access property within the .subscribe() block like so:

ngOnInit() {
    this._userRelated.getOneUser(this.pname).subscribe(data=> {
      this.showuser = data;
      this.access = this.showuser.userAccess; 
      console.log(this.showuser);
     ]);
    this.regularForm = this._fb.group({
      'id': [{value:'', disabled: true}, Validators.required],
      'name':[{value:'', disabled: true}, Validators.required],
      'username':[{value:'', disabled: true}, Validators.required],
      'role':[{value:'', disabled: true}, Validators.required],
      'status':[{value:'', disabled: true}, Validators.required],
      'state':[{value:'', disabled: true}, Validators.required],
      'pincode':[{value:'', disabled: true}, Validators.required],
      'mobileno':[{value:'', disabled: true}, Validators.required],
      'address':[{value:'', disabled: true}, Validators.required],
    });

  }

Answer №2

When you're working with the this.showuser data in the subscribe function, keep in mind that it's an asynchronous process. This means that there will be a delay between when the data is requested and when it actually arrives back from the server to the client. Trying to use this data in a synchronous operation like inserting it into this.acess can lead to issues because the data may not be available yet.

To avoid this issue, make sure to insert the data into this.acess within the subscribe function itself. This way, you can guarantee that the data is present before trying to use it in any further operations.

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