Angular post data is not going to Django REST API - django

Question

I'm using Angular 6 and Django REST Framework
The view of DRF is
class AmountGivenViewSet(viewsets.ModelViewSet):
serializer_class = AmountGivenSerializer
permission_classes = (IsAuthenticated, AdminAuthenticationPermission,)
def get_queryset(self):
return AmountGiven.objects.filter(
contact__user=self.request.user
)
def perform_create(self, serializer):
save_data = {}
print(self.request.POST)
# validate user and to save_data dictionary
contact_pk = self.request.POST.get('contact', None)
print(contact_pk)
if not contact_pk:
raise ValidationError({'contact': ['Contact is required']})
contact = Contact.objects.filter(
user=self.request.user,
pk=contact_pk
).first()
if not contact:
raise ValidationError({'contact': ['Contact does not exists']})
# add contact to save_data dictionary
save_data['contact'] = contact
# process mode_of_payment is in request
mode_of_payment_pk = self.request.POST.get('mode_of_payment', None)
if mode_of_payment_pk:
mode_of_payment = ModeOfPayment.objects.get(pk=mode_of_payment_pk)
if not mode_of_payment:
raise ValidationError({'mode_of_payment': ['Not a valid mode of payment']})
# add mode_of_payment to save_data dictionary
save_data['mode_of_payment'] = mode_of_payment
# pass save_data dictionary to save()
serializer.save(**save_data)
AmountGivenSerializer in serializers.py
class AmountGivenSerializer(serializers.ModelSerializer):
class Meta:
model = AmountGiven
depth = 1
fields = (
'id', 'contact', 'amount', 'interest_rate', 'duration', 'given_date', 'promised_return_date',
'mode_of_payment', 'transaction_number', 'interest_to_pay', 'total_payable', 'amount_due',
'total_returned', 'comment', 'modified', 'created'
)
and in Angular component
import { Component, OnInit } from '#angular/core';
import {FormBuilder, FormControl, FormGroup, Validators} from '#angular/forms';
import {AmountGiven} from '../amount-given.model';
import {AmountGivenService} from '../amount-given.service';
import {ActivatedRoute} from '#angular/router';
#Component({
selector: 'app-amount-given-add',
templateUrl: './amount-given-add.component.html',
styleUrls: ['./amount-given-add.component.css']
})
export class AmountGivenAddComponent implements OnInit {
addMoneyForm: FormGroup;
submitted = false;
contact_id: string;
amountGiven: AmountGiven;
constructor(
private formBuilder: FormBuilder,
private amountGivenService: AmountGivenService,
private route: ActivatedRoute
) { }
ngOnInit(): void {
this.route.params.subscribe(
param => {
this.contact_id = param['contact_id'];
}
);
this.addMoneyForm = this.formBuilder.group({
amount: new FormControl('', [
Validators.required
]),
interest_rate: new FormControl(),
duration: new FormControl(),
given_date: new FormControl(),
promised_return_date: new FormControl(),
transaction_number: new FormControl(),
mode_of_payment: new FormControl(),
comment: new FormControl()
});
}
get f() {
return this.addMoneyForm.controls;
}
onSubmit() {
this.submitted = true;
// stop here if form is invalid
if (this.addMoneyForm.invalid) {
console.log('invalid');
return;
}
const data = this.addMoneyForm.value;
data.contact = this.contact_id;
this.amountGivenService.add(data).subscribe(res => {
console.log('req completed', res);
});
}
}
But when form is submited it returns validation error from server for contact field.
{"contact":["Contact is required"]}
The request header has the contact parameter
sending the same request from Postman is working fine. The Javascript XHR code of Postman request is
var data = new FormData();
data.append("amount", "5000");
data.append("contact", "65827a1f-003e-4bb3-8a90-6c4321c533e6");
var xhr = new XMLHttpRequest();
xhr.withCredentials = true;
xhr.addEventListener("readystatechange", function () {
if (this.readyState === 4) {
console.log(this.responseText);
}
});
xhr.open("POST", "https://koober-production.herokuapp.com/api/amount-given/");
xhr.setRequestHeader("Authorization", "Bearer ATjIuQ6hLzc55wHaXIzHmcKafEzk1B");
xhr.setRequestHeader("Cache-Control", "no-cache");
xhr.setRequestHeader("Postman-Token", "28d9d33a-f0a6-431c-8936-da4f6565ece4");
xhr.send(data);
could not understand this issue is related to Angular or Django because Postman request is working fine with Djano and Angular is sending the request in the parameter.
Edit 2: AmountGivenService
import { Injectable } from '#angular/core';
import {ResourceProviderService} from '../../resource-provider.service';
import {AuthService} from '../../auth/auth.service';
import {Observable, of} from 'rxjs';
import {AmountGiven} from './amount-given.model';
import {AppHttpClient} from '../../app-http-client';
#Injectable({
providedIn: 'root'
})
export class AmountGivenService {
private url = 'amount-given/';
constructor(
private http: AppHttpClient
) { }
add(data): Observable<AmountGiven> {
return this.http.Post<AmountGiven>(this.url, data);
}
}
which is furhter using AppHttpClient
import { Injectable } from '#angular/core';
import {HttpClient, HttpHeaders, HttpParams} from '#angular/common/http';
import {Observable, of} from 'rxjs';
import {catchError} from 'rxjs/operators';
import {ResourceProviderService} from './resource-provider.service';
export interface IRequestOptions {
headers?: HttpHeaders;
observe?: 'body';
params?: HttpParams;
reportProgress?: boolean;
responseType?: 'json';
withCredentials?: boolean;
body?: any;
}
export function appHttpClientCreator(http: HttpClient, resource: ResourceProviderService) {
return new AppHttpClient(http, resource);
}
#Injectable({
providedIn: 'root'
})
export class AppHttpClient {
private api_url = this.resource.url + '/api/';
constructor(
public http: HttpClient,
private resource: ResourceProviderService
) {
}
public Post<T>(endPoint: string, params: Object, options?: IRequestOptions): Observable<T> {
return this.http.post<T>(this.api_url + endPoint, params, options)
.pipe(
catchError(this.handleError('post', endPoint, null))
);
}
private handleError<T> (operation = 'operation', endpoint = '', result?: T) {
return (error: any): Observable<T> => {
console.error(error);
console.log(error.message);
console.log(operation);
console.log(endpoint);
return of(result as T);
};
}
}

Answer 1

The problem is that you're trying to access:
self.request.POST.get('contact', None)
in DRF you need to do:
self.request.data.get('contact', None)
It works from postman because you're constructing a FormData object which is fundamentally different from the JSON body angular will send and that is expected by a RESTful API like DRF.
from a more general standpoint, in DRF, serializers should perform the request validation using the built in validators, rather than manually validating in the view.

Answer 2

I'm hesitant to add this as the answer just yet, but it feels like you need to add something along the lines of:
<form method="POST" action="url/to/your-DRF-endpoint" enctype="application/x-www-form-urlencoded">
....
</form>
Either within your template or within your Angular POST request code you need to make sure the data is posted as application/x-www-form-urlencoded.
Essentially, Django expects application/x-www-form-urlencoded, and without it your self.request.POST object will be empty and hence self.request.POST.get('contact', None) will be empty and default to None.