gistfile1.txt

import {
  Directive,
  InjectFlags,
  Input,
  OnInit,
  ɵɵdirectiveInject as inject,
} from '@angular/core';
import { ControlContainer } from '@angular/forms';
import { FormArray, FormBuilder, FormGroup } from '@ngneat/reactive-forms';

@Directive()
export abstract class FormArrayComponent<T extends object = any>
  implements OnInit {
  protected readonly _fb: FormBuilder;
  protected readonly _parent?: ControlContainer;

  @Input('formArray')
  form: FormArray<T>;

  @Input()
  formArrayName: string;

  constructor() {
    this._fb = inject(FormBuilder);
    this._parent = inject(
      ControlContainer,
      InjectFlags.Host | InjectFlags.Optional | InjectFlags.SkipSelf
    );
  }

  // -----------------------------------------------------------------------------------------------------
  // @ Lifecycle hooks
  // -----------------------------------------------------------------------------------------------------

  /**
   * On init
   */
  ngOnInit() {
    this._initForm();
  }

  // getFormArray<K extends keyof T>(prop: K): FormArray<T[K]> {
  //   return this.form.get(prop as string) as any;
  // }

  // getFormGroup<K extends keyof T>(prop: K): FormGroup<T[K]> {
  //   return this.form.get(prop as string) as any;
  // }

  // -----------------------------------------------------------------------------------------------------
  // @ Private methods
  // -----------------------------------------------------------------------------------------------------

  private _initForm() {
    if (this.form) return;

    this.form = this.createForm();

    const parentForm = this._parent?.control;

    if (parentForm instanceof FormGroup && this.formArrayName) {
      if (parentForm.contains(this.formArrayName)) {
        this.form = parentForm.get(this.formArrayName) as FormArray<T>;
      } else {
        parentForm.addControl(this.formArrayName, this.form);
      }
    }
  }

  protected createForm() {
    return this._fb.array<T>([]);
  }
}