Angular 8 patch request httpclient.subscribe() doesnt hit response, err or () - rxjs

Question

I am encountering an issue I do not understand.
Inside one service I have the following code.
when the code hits PATCH LINE, it jumps immediately to RETURN NOTHING LINE.
the catchError line is not hit.
the () line is not hit
the err line is not hit.
I have compared this to working services and I do not see any difference.
patchItem(item_: Project): Observable<Project> {
const url: string = `${this.serviceUrl}/${item_.id}`;
const data = JSON.stringify(item_);
console.log('inside patch item');
console.log(url);
this.http.patch(url, data, httpOptions) //PATCH LINE
.pipe(
catchError(err => this.handleError('PatchItem', err))
)
.subscribe((response) => {
console.log('item patched ');
return this.myResponse.push(response);
}
, err => console.log("inline error encountered")
,() => console.log("this seems to have completed")
);
console.log("return nothing"); //RETURN NOTHING LINE
return null;
}
The API is C# webapi 2
It is being hit.
There is a problem though, I am expecting the JSON to be passed in and webForm_ is always NULL.
This is probably an important clue.
Again, i compare this to working calls and can not find a difference.
When I inspect the variable in jquery, it has the correct value.
In postman, i get the expected response.
[System.Web.Http.HttpPatch]
[Route("{itemId_}")]
public IHttpActionResult PatchById([FromUri] int itemId_, [FromBody] Models.mpgProject webForm_)
{
return JSONStringResultExtension.JSONString(this, "foobar for now", HttpStatusCode.OK);
}
To save a cycle, here is the handleError function.
I have copy/pasted this from a service that is working as expected.
protected handleError<T>(operation = 'operation', result?: T) {
return (error: any): Observable<T> => {
console.error(error); // log to console instead
console.log(`${operation} failed: ${error.message}`);
// Let the app keep running by returning an empty result.
return of(result as T);
};
}
How can Angular be skipping all the subscription stuff when it IS actually calling the API?
I think it has to be a simple syntax issue, but I have been staring at it for hours... :-(
Happy to post any other code requested...
tyia
ps - I would also be happy to retitle the question. I am at a loss for how to phrase a good question title for this...

Answer 1

Your handleError method returns a function (that returns an Observable) when it should return an Observable.
It looks as if the error handler you copied from another service does not fit here.
I could imagine an error handler like this:
private handleError<T>(operation = "operation", error: HttpErrorResponse) {
console.error(error); // log to console instead
console.log(`${operation} failed: ${error.message}`);
// Let the app keep running by returning an empty result.
return of({} as T);
}
This method returns an Observable of an empty object. However, this might not be the best option to react on a failing HTTP PATCH request. You would better throw that error up to the component and let the user retry.