The potential object null may lead to an absence of the 'value' property in the type 'EventTarget'

Question

The potential object null may lead to an absence of the 'value' property in the type 'EventTarget'

I am facing a problem that I am unable to resolve. The error in my HTML reads: Object is possibly 'null' and Property 'value' does not exist on type 'EventTarget'.

HTML

<select [(ngModel)]="selectedProvincia" (change)="onSelect($event.target.value)" name="provincias" id="ps-prov" class="form-select">
      <option *ngFor="let provincias of provincias" value="{{provincias.code}}">{{provincias.label}}</option>
      </select>

TS

 onSelect(code: string): void {
    this.municipios = this.newPersonService
      .getMunicipios()
      .filter((item) => item.parent_code === code);
  }

I have been searching for a solution but haven't been able to find one yet.

angular typescript

Answer 1

Answer №1

One reason for this issue is that TypeScript does not automatically determine the type of the event target when accessing event.target.value. To fix this problem, you can explicitly cast the event.target to the appropriate type.

onSelect($event: Event): void {
  const selectedValue = ($event.target as HTMLSelectElement).value;
  this.municipios = this.newPersonService
    .getMunicipios()
    .filter((item) => item.parent_code === selectedValue);
}

And in Html

<select
  [(ngModel)]="selectedProvincia"
  (change)="onSelect($event)"
  name="provincias"
  id="ps-prov"
  class="form-select"
>
  <option
    *ngFor="let provincias of provincias"
    value="{{provincias.code}}"
  >
    {{provincias.label}}
  </option>
</select>

Answer 2

One reason for this issue is that TypeScript does not automatically determine the type of the event target when accessing event.target.value. To fix this problem, you can explicitly cast the event.target to the appropriate type.

onSelect($event: Event): void {
  const selectedValue = ($event.target as HTMLSelectElement).value;
  this.municipios = this.newPersonService
    .getMunicipios()
    .filter((item) => item.parent_code === selectedValue);
}

And in Html

<select
  [(ngModel)]="selectedProvincia"
  (change)="onSelect($event)"
  name="provincias"
  id="ps-prov"
  class="form-select"
>
  <option
    *ngFor="let provincias of provincias"
    value="{{provincias.code}}"
  >
    {{provincias.label}}
  </option>
</select>

Answer 3

Answer №2

It is important to avoid creating variables in loops with the same name as the list (for example, change the variable name after 'let' to the singular form of the word).
If you are dependent on a model change event, consider using ngModelChange instead of the banana-in-a-box pattern [()].
An effective pattern to follow is to create a method called getMunicipiosByCode(code: string).

<select [ngModel]="selectedProvincia" (ngModelChange)="onSelect($event)">
  <option *ngFor="let provincia of provincias" [value]="provincia.code">
    {{ provincia.label }}
  </option>
</select>


onSelect(code: string): void {
  this.municipios = this.newPersonService
    .getMunicipios()
    .filter((item) => item.parent_code === code);
}

Answer 4

It is important to avoid creating variables in loops with the same name as the list (for example, change the variable name after 'let' to the singular form of the word).
If you are dependent on a model change event, consider using ngModelChange instead of the banana-in-a-box pattern [()].
An effective pattern to follow is to create a method called getMunicipiosByCode(code: string).

<select [ngModel]="selectedProvincia" (ngModelChange)="onSelect($event)">
  <option *ngFor="let provincia of provincias" [value]="provincia.code">
    {{ provincia.label }}
  </option>
</select>


onSelect(code: string): void {
  this.municipios = this.newPersonService
    .getMunicipios()
    .filter((item) => item.parent_code === code);
}

The potential object null may lead to an absence of the 'value' property in the type 'EventTarget'

Answer №1

Answer №2

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