Angular 4.3 HttpClient put doesn't fire [duplicate]

Question

I've got this httpclient request in an angular 4.3 service:

updateTermin(termin: Termin){
  let url = '${this.termineUrl}/${termin.id}';
  this.http
  .put(url, termin, {headers: this.headers})
}

it only gets fired if i append a .subscribe() like this:

updateTermin(termin: Termin){
  let url = '${this.termineUrl}/${termin.id}';
  this.http
  .put(url, termin, {headers: this.headers})
  .subscribe()
}

The other request (delete or post) work without append .subscribe(). Why?

No, they don't. You need to subscribe for a HTTP request to be sent, whatever the method is. — JB Nizet
– JB Nizet, Commented Oct 24, 2017 at 17:16

BeetleJuice · Accepted Answer · 2017-10-24 17:44:33Z

19

The HttpClient request methods (all of them) return an Observable: basically it's a chain of commands waiting to be executed. Nothing happens until you call subscribe() on that chain. So this.http.put(...) only prepares the commands for you.

If you're coming from an environment that uses promises, this will seem counter-intuitive because a promise executes as soon as it comes alive. Observables are different. Check out this short intro on YouTube

edited Oct 24, 2017 at 17:44

answered Oct 24, 2017 at 17:33

BeetleJuice

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2 Comments

Jacques Over a year ago

spot on, never knew about waiting on the call to subscribe!

saravanakumar Over a year ago

Almost half day digging this issue.. Thanks @BeetleJuice for the answer.

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