What is the correct way to transfer a function from a component.ts file to a service file?

Question

What is the correct way to transfer a function from a component.ts file to a service file?

I recently wrote a function in my component.ts file that sends a PUT request. It was working perfectly fine, but I decided to refactor and move the function to a service.ts file. After moving it, the functionality seems to have broken. Whenever I click on the "Save" button, an error is displayed in the console:

FormsComponent.html:32 ERROR TypeError: _co.editForm is not a function at Object.eval [as handleEvent] (FormsComponent.html:32) at handleEvent (core.js:23008) at callWithDebugContext (core.js:24078) at Object.debugHandleEvent [as handleEvent] (core.js:23805) at dispatchEvent (core.js:20457) at core.js:20904 at HTMLButtonElement. (platform-browser.js:993) at ZoneDelegate.push../node_modules/zone.js/dist/zone.js.ZoneDelegate.invokeTask (zone.js:423) at Object.onInvokeTask (core.js:17279) at ZoneDelegate.push../node_modules/zone.js/dist/zone.js.ZoneDelegate.invokeTask (zone.js:422) View_FormsComponent_0 @ FormsComponent.html:32 proxyClass @ compiler.js:18234 push../node_modules/@angular/core/fesm5/core.js.DebugContext_.logError @ core.js:24040 push../node_modules/@angular/core/fesm5/core.js.ErrorHandler.handleError @ core.js:15761 dispatchEvent @ core.js:20461 (anonymous) @ core.js:20904 (anonymous) @ platform-browser.js:993 push../node_modules/zone.js/dist/zone.js.ZoneDelegate.invokeTask @ zone.js:423 onInvokeTask @ core.js:17279 push../node_modules/zone.js/dist/zone.js.ZoneDelegate.invokeTask @ zone.js:422 push../node_modules/zone.js/dist/zone.js.Zone.runTask @ zone.js:195 push../node_modules/zone.js/dist/zone.js.ZoneTask.invokeTask @ zone.js:498 invokeTask @ zone.js:1744 globalZoneAwareCallback @ zone.js:1770 FormsComponent.html:32 ERROR CONTEXT DebugContext_ {view: {…}, nodeIndex: 31, nodeDef: {…}, elDef: {…}, elView: {…}}

The following is my forms.component.ts file:

import { Component, OnInit, OnDestroy } from '@angular/core';
import { ActivatedRoute, Router } from '@angular/router';
import { FormService } from './forms.service';
import { form } from './form-interface';
import { HttpClient } from '@angular/common/http';

@Component({
  selector: 'app-forms',
  templateUrl: './forms.component.html',
  styleUrls: ['./forms.component.css']
})


export class FormsComponent implements OnInit {

  formsUrl = "https://jsonplaceholder.typicode.com/posts";
  id: any;
  form: form = {
    id: 0,
    userId: 0,
    title: '',
    body: ''
  };

  constructor(private formService: FormService ,private route: ActivatedRoute,
    private router: Router, private http: HttpClient) { }

  ngOnInit() {
    this.id=this.route.snapshot.params['id'];

    this.formService.getForms(this.id).subscribe(
      (forms: any) => {
        this.form = forms[0];
        console.log(this.form);
      }
    );

  }

  deleteForm() {
    this.http.delete(this.formsUrl + "/" + this.form.id)
    .subscribe(
      data  => {
      console.log("DELETE Request is successful ", data);
      },
      error  => {
      console.log("Error", error);
      }
    );
  }

}

Below is my forms.service.ts file:

import { Injectable } from '@angular/core';
import { HttpClient } from '@angular/common/http';
import { form } from './form-interface';



@Injectable({
    providedIn: 'root'
}) 

export class FormService {

formsUrl = "https://jsonplaceholder.typicode.com/posts";
form: form = {
    id: 0,
    userId: 0,
    title: '',
    body: ''
  };


    constructor(private http: HttpClient) { }

    getForms(id) {
        return this.http.get('https://jsonplaceholder.typicode.com/posts'
        + "?id=" + id)
      }

      editForm() {
        fetch(this.formsUrl + "/" + this.form.id, {
          method: 'PUT',
          body: JSON.stringify(this.form),
          headers: {
            "Content-type": "application/json; charset=UTF-8"
          }
        })
        .then(response => response.json())
        .then(json => console.log(json));
      }


}

Lastly, here is my HTML file:

<div class="forms container">
  <form #postForm="ngForm">
      <div class="form-group">
          <label for="title">Title</label>
          <input [(ngModel)]="form.title"
          name="title"  
          id="title" 
          type="text" 
          class="form-control"
          >
      </div>
      <div class="form-group">
        <label for="body">Body</label>
        <textarea [(ngModel)]="form.body" 
        name= "body" 
        id="body" 
        cols="30" 
        rows="10" 
        class="form-control"
        ></textarea>
      </div>
      <button class="btn btn-success" (click) = editForm()>Save</button>
      <button class="btn btn-danger pull-right" (click) = deleteForm()>Delete</button>
  </form>
</div>

javascript angular typescript

Answer 1

Answer №1

If you're aiming to maintain cleanliness and organization in your code, consider implementing something along these lines:

export class FormsComponent implements OnInit {
  form = this.formService.getForm();

  constructor(private formService: FormService, private route: ActivatedRoute,
    private router: Router) { }

  ngOnInit() {
    this.id = this.route.snapshot.params['id'];

    this.formService.loadFormById(this.id)
        .subscribe(([form]) => this.formService.updateForm(form));
  }

  saveForm() {
    this.formService.saveForm();
  }

  deleteForm() {
    this.formService.deleteForm();
  }

}

As for the Service:

export class FormService {

    formsUrl = "https://jsonplaceholder.typicode.com/posts";
    form: form = {
       id: 0,
       userId: 0,
       title: '',
       body: ''
    };


    constructor(private http: HttpClient) { }

    loadFormById(id) {
       // Load the specific form here
    }

    updateForm(form) {
       // Update the form details here
    }

    saveForm() {
       // Save the form data here
    }

    deleteForm() {
       // Delete the form as required
    }
}

Answer 2

If you're aiming to maintain cleanliness and organization in your code, consider implementing something along these lines:

export class FormsComponent implements OnInit {
  form = this.formService.getForm();

  constructor(private formService: FormService, private route: ActivatedRoute,
    private router: Router) { }

  ngOnInit() {
    this.id = this.route.snapshot.params['id'];

    this.formService.loadFormById(this.id)
        .subscribe(([form]) => this.formService.updateForm(form));
  }

  saveForm() {
    this.formService.saveForm();
  }

  deleteForm() {
    this.formService.deleteForm();
  }

}

As for the Service:

export class FormService {

    formsUrl = "https://jsonplaceholder.typicode.com/posts";
    form: form = {
       id: 0,
       userId: 0,
       title: '',
       body: ''
    };


    constructor(private http: HttpClient) { }

    loadFormById(id) {
       // Load the specific form here
    }

    updateForm(form) {
       // Update the form details here
    }

    saveForm() {
       // Save the form data here
    }

    deleteForm() {
       // Delete the form as required
    }
}

Answer 3

Answer №2

If you find yourself trying to call the editForm() function in the template but it does not exist in your component, there is a simple solution. Rather than attempting to call the function directly from the template, you can invoke it from the service using formService.editForm().

To successfully utilize this approach, ensure that the formService variable is made public, enabling you to access it throughout your component. Update private formService: FormService to public formService: FormService, allowing for seamless functionality.

An alternative method involves duplicating the function within the component itself, eliminating the need to modify the template or alter the service visibility. Define a new public function like

public editForm = formService.editForm

for convenient access.

Alternatively, you can explicitly define the editForm() function within the component as shown below:

editForm() {
     return this.formService.editForm();
}

Answer 4

If you find yourself trying to call the editForm() function in the template but it does not exist in your component, there is a simple solution. Rather than attempting to call the function directly from the template, you can invoke it from the service using formService.editForm().

To successfully utilize this approach, ensure that the formService variable is made public, enabling you to access it throughout your component. Update private formService: FormService to public formService: FormService, allowing for seamless functionality.

An alternative method involves duplicating the function within the component itself, eliminating the need to modify the template or alter the service visibility. Define a new public function like

public editForm = formService.editForm

for convenient access.

Alternatively, you can explicitly define the editForm() function within the component as shown below:

editForm() {
     return this.formService.editForm();
}

Answer 5

Answer №3

it appears there is a parsing error. Please correct the HTML errors:

add (click) = "editForm()" and (click) = "deleteForm()"

<div class="forms container">
  <form #postForm="ngForm">
      <div class="form-group">
          <label for="title">Title</label>
          <input [(ngModel)]="form.title"
          name="title"  
          id="title" 
          type="text" 
          class="form-control"
          >
      </div>
      <div class="form-group">
        <label for="body">Body</label>
        <textarea [(ngModel)]="form.body" 
        name= "body" 
        id="body" 
        cols="30" 
        rows="10" 
        class="form-control"
        ></textarea>
      </div>
      <button class="btn btn-success" (click) = "editForm()">Save</button>
      <button class="btn btn-danger pull-right" (click) = "deleteForm()">Delete</button>
  </form>
</div>

Answer 6

it appears there is a parsing error. Please correct the HTML errors:

add (click) = "editForm()" and (click) = "deleteForm()"

<div class="forms container">
  <form #postForm="ngForm">
      <div class="form-group">
          <label for="title">Title</label>
          <input [(ngModel)]="form.title"
          name="title"  
          id="title" 
          type="text" 
          class="form-control"
          >
      </div>
      <div class="form-group">
        <label for="body">Body</label>
        <textarea [(ngModel)]="form.body" 
        name= "body" 
        id="body" 
        cols="30" 
        rows="10" 
        class="form-control"
        ></textarea>
      </div>
      <button class="btn btn-success" (click) = "editForm()">Save</button>
      <button class="btn btn-danger pull-right" (click) = "deleteForm()">Delete</button>
  </form>
</div>

What is the correct way to transfer a function from a component.ts file to a service file?

Answer №1

Answer №2

Answer №3

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What is the correct way to transfer a function from a component.ts file to a service file?

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Answer №2

Answer №3

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