show database fetched values if present else show default text in ng-select angular

From what I understand you are using Reactive Forms to manage these controls. If this is not true, please let me know.

The HTML template I am suggesting is similar to yours, but simpler. I am recommending to not add a separate <ng-option> for the selected value / default message:

<ng-select formControlName="country" (change)="onChangeCountry($event)" style="width: 200px;">
  <ng-option *ngFor="let country of countries" [value]="country.id">{{country.name}}</ng-option>
</ng-select>

<ng-select formControlName="state" (change)="onChangeState($event)" style="width: 200px;">
  <ng-option *ngFor="let state of statesToShow" [value]="state.id">{{state.name}}</ng-option>
</ng-select>

<ng-select formControlName="city" (change)="onChangeCity($event)" style="width: 200px;">
  <ng-option *ngFor="let city of citiesToShow" [value]="city.id">{{city.name}}</ng-option>
</ng-select>

I have also included a TS file with working example on how to set

1. The placeholder messages when appropriate.
2. The already selected value. Please see prefefinedValues() function.

Please note that in order for 2. to work as expected, the ID of the element needs to be in the data source currently selected for the control (in my example statesToShow or citiesToShow). If not, it will be displayed as text (probably what you are experiencing).

import { Component } from '@angular/core';
import { FormBuilder, FormGroup, FormsModule } from '@angular/forms';

@Component({
  selector: 'app-root',
  templateUrl: './app.component.html',
  styleUrls: ['./app.component.css']
})
export class AppComponent {
  title = 'test2';

  guestForm: FormGroup;

  selectedCar: number = 0;

  // this is the data source for the STATES drop-down (initially empty)
  // => will be populated when a COUNTRY is selected
  public statesToShow: Array<any> = [];
  // this is the data source for the CITIES drop-down (initially empty)
  // => will be populated when a STATE is selected
  public citiesToShow: Array<any> = [];

  // TEST data start
  public countries = [
      { id: 1, name: 'Romania' },
      { id: 2, name: 'USA' },
      { id: 3, name: 'France' },
      { id: 4, name: 'Spain' },
  ];

  public states = [
    [],
    [
      {id: 1, name: "Cluj"},
      {id: 2, name: "Valcea"},
      {id: 3, name: "Sibiu"},
      {id: 4, name: "Mures"},
    ],
    [
      {id: 5, name: "New York"},
      {id: 6, name: "Oregon"},
      {id: 7, name: "Arizona"},
      {id: 8, name: "Texas"},
    ],
    [
      {id: 9, name: "Normandie"},
      {id: 10, name: "Ile-de-France"},
      {id: 11, name: "Grand Est"},
      {id: 12, name: "Occitanie"},
    ],
    [
      {id: 13, name: "Alicante"},
      {id: 14, name: "Valencia"},
      {id: 15, name: "Sevilla"},
      {id: 16, name: "Malaga"},
    ]
  ];


  public cities = [
    [],
    [
      {id: 1, name: "Cluj-Napoca"},
      {id: 2, name: "Turda"},
      {id: 3, name: "Huedin"},
    ],
    [
      {id: 4, name: "Ramnicul Valcea"},
      {id: 5, name: "Horezu"},
      {id: 6, name: "Olanesti"},
    ],
    [],
    [],
    [
      {id: 10, name: "New York city 1"},
      {id: 11, name: "New York city 2"},
      {id: 12, name: "New York city 3"},
    ],
    [
      {id: 13, name: "Oregon city 1"},
      {id: 14, name: "Oregon city 2"},
      {id: 15, name: "Oregon city 3"},
    ]
  ]

  // TEST data end

  private dbCountryId: number | null = null;
  private dbStateId: number | null = null;
  private dbCityId: number | null = null;
  
  constructor(private _fb: FormBuilder) {
    // add default placeholder messages for all the controls
    this.guestForm = this._fb.group({
      country: ['Please select country', null],
      state: ['Please select state', null],
      city: ['Please select city', null]
    });
  }

  ngOnInit() {
    
  }

  onChangeCountry(value: number) {
    // set the data source for the STATES drop-down
    this.statesToShow = this.states[value];
    // display placeholders for STATES and CITIES until the user
    // selects the values
    this.guestForm.patchValue({ 
      state: "Please select state !",
      city: "Please select city !"
    });
  }

  onChangeState(value: number) {
    // set the data source for the CITIES drop-down
    this.citiesToShow = this.cities[value] ? this.cities[value] : [];
    // display the placeholder until the user selects a new city
    this.guestForm.patchValue({ city: "Please select city !" });
  }

  onChangeCity(value: number) {
    console.log(value);
  }

  // example on how to correctly set preselected values
  // in the controls
  predefinedValues() {
    // preselected values (MUST BE A VALID COMBINATION)
    this.dbCountryId = 2;
    this.dbStateId = 6;
    this.dbCityId = 14;

    // set the sources for STATES and CITIES drop-downs
    this.statesToShow = this.states[this.dbCountryId];
    this.citiesToShow = this.cities[this.dbStateId];

    // set the preselected IDs as current value in all drop-downs
    this.guestForm.patchValue({ 
      country: this.dbCountryId,
      state: this.dbStateId,
      city: this.dbCityId
    });
  }
}

EDIT: loading data from a server

When the data is received from a server, we need to wait for the information to arrive before making any patching to the form control. The predefinedValues function changes to:

predefinedValues() {
  // read saved database values:
  this._dataService.getSavedDatabaseValues()
    .then(data => {
      this.dbCountryId = data.dbCountryId;
      this.dbStateId = data.dbStateId;
      this.dbCityId = data.dbCityId;

      // now that we have the saved IDs, 
      // load countries, states & cities for the saved data
      this._dataService.getCountries()
        .then(data => {
          this.countriesToShow = data;
          // now that the data binding to the control is complete
          // we can do the patching
          this.guestForm.patchValue({
            country: this.dbCountryId
          });
        });

      this._dataService.getStates(this.dbCountryId)
        .then(data => {
          this.statesToShow = data;
          // now that the data binding to the control is complete
          // we can do the patching
          this.guestForm.patchValue({
            state: this.dbStateId
          });
        });

      this._dataService.getCities(this.dbStateId)
        .then(data => {
          this.citiesToShow = data;
          // now that the data binding to the control is complete
          // we can do the patching
          this.guestForm.patchValue({
            city: this.dbCityId
          });
        });
    })
}

This function can be called directly in ngOnInit to load the previously saved data. Also, when one of the countries or states selections change, we need to load the data from the server.

onChangeCountry(value: number) {
  // set the data source for the STATES drop-down
  this._dataService.getStates(value)
    .then(data => {
      this.statesToShow = data;
    });
  // display placeholders for STATES and CITIES until the user
  // selects the values
  this.guestForm.patchValue({
    state: "Please select state !",
    city: "Please select city !"
  });
}

Edit 2: In order to fix the issue with the required validation, I am suggesting a custom validator:

import {AbstractControl, ValidatorFn} from '@angular/forms';

export function selectIsRequired(): ValidatorFn {  
    return (control: AbstractControl): { [key: string]: any } | null =>  {
      console.log("validator:", control.value);
        return control.value === 'Select Country' 
                || control.value === 'Select State'
                || control.value === 'Select City'
                || isNaN(parseInt(control.value))
            ? {required: control.value} : null;
    }
}

This will be applied on the select controls like this:

this.guestForm = this._fb.group({
      country: ['Select country', selectIsRequired()],
      state: ['Select state', selectIsRequired()],
      city: ['Select city', selectIsRequired()]
    });

This solution seems to work. You need formControl functionality in the ngOnInit function of the controller. Hope this helps.

In the html file, I have:

<div class="position">
  <form [formGroup]="FormOne">
    <ng-select
      [formControlName]="city"
      (change)="onChangeCity($event)"
      placeholder="Select City"
      ><ng-option *ngFor="let city of cities" [value]="city.id">{{
        city.name
      }}</ng-option>
    </ng-select>
  </form>
 </div>

in the Controller I have this for example sake:

import { Component, OnInit } from '@angular/core';
import {
  FormGroup,
  Validators,
  FormControl,
  AbstractControl,
} from '@angular/forms';

@Component({
  selector: 'my-app',
  templateUrl: './app.component.html',
  styleUrls: ['./app.component.css'],
})
export class AppComponent implements OnInit {
  cities = [
    { id: 1, name: 'abc' },
    { id: 2, name: 'def' },
    { id: 3, name: 'ghi' },
    { id: 4, name: 'jkl' },
    { id: 5, name: 'mno' },
  ];
  FormOne: FormGroup;

  constructor() {}

  ngOnInit() {
    this.FormOne = new FormGroup({
      city: new FormControl(null, Validators.required),
    });
  }
 
}

you should try items instate of option as bellow

<ng-container ngFor="let country in countries"> \\ you can apply forloop like this and it will show default value
    <ng-select
      [items]="{{country.name}}"
      formControlName="country"
      bindLabel="label"                 
      [multiple]="true"
      placeholder="Select Country"
      [(ngModel)]="selectedAttributes">
    </ng-select>
</ng-container>

add following modules

import { NgSelectModule } from '@ng-select/ng-select';
import { FormsModule } from '@angular/forms';


@NgModule({
  imports: [
    FormsModule,
    NgSelectModule,
 

for more information you can checkout this link ng-select docs