Why does my Angular http.delete send "null" instead of null?

Question

I have the following in my Angular service:

this.$http.delete<void>(ApiDomain.superPlan, `/v1/Attendance?resultEventId=${resultEventId}&dueEventId=${dueEventId}`)

And this is the signature of the C# method being called:

        [HttpDelete(),
        public async Task<IActionResult> Delete(string resultEventId, string dueEventId)

The dueEventId passed in is sometimes null. Yet in the C# method, its value is "null" instead of null. How do I pass the actual null value?

Does this answer your question? [Parse null query parameters in AspNet Core](https://stackoverflow.com/questions/51478601/parse-null-query-parameters-in-aspnet-core) — Heretic Monkey, May 13 '22 at 19:41

StriplingWarrior · Answer 1 · 2022-05-13T19:48:56.263

1

When JavaScript is concatenating strings, if it comes across null it will insert "null" into the given string.

console.log(`/v1/Attendance?resultEventId=${1}&dueEventId=${null}`);
// output: /v1/Attendance?resultEventId=1&dueEventId=null

To avoid that, you can avoid including the dueEventId query parameter at all if its value is null. Or leave the value empty: ASP.NET Core will interpret an empty string as null, as pointed out by Heretic Monkey in the comments.

edited May 13 '22 at 19:48

answered May 13 '22 at 19:38

StriplingWarrior

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Or pass the key without a value (e.g. `dueEventId=`), as described in the duplicate. – Heretic Monkey May 13 '22 at 19:42

score 0 · Answer 2 · answered May 13 '22 at 20:58

Rewrite to ommit param with null value

let params=new HttpParams().append("resultEventId",""+resultEventId})
if(dueEventId){
   params=params.append("dueEventId",""+dueEventId);
}
this.$http.delete<void>(ApiDomain.superPlan, `/v1/Attendance`,{params});

otherwise you are sending dueEventId="null" which is exactly what you observe.

Why does my Angular http.delete send "null" instead of null?

2 Answers2