subsequent calls to AddUrlSegment do not change value

[gregveres]

I have a situation where part of my code sets a URL Segment to a value, and then calls the a function that executes the request with a retry if the auth fails.

Part of refreshing the auth retrieves the correct value of the URL Segment. So, I need to call AddUrlSegment again with the new, proper value and then execute the request again, now with the proper value.

But that doesn't work. RestSharp always uses the original value of the URL Segment. Here is a code snippet that illustrates the undesirable behaviour:

 RestClient client = new RestClient();
 var request = new RestRequest("https://api.example.com/orgs/{segment}/something");
 request.AddUrlSegment("segment", 1);
 var url1 = client.BuildUri(request);
 request.AddUrlSegment("segment", 2);
 var url2 = client.BuildUri(request);

Expected out come:
url1 = {https://api.example.com/orgs/1/something}
url2 = {https://api.example.com/orgs/2/something}

actual out come:
url1 = {https://api.example.com/orgs/1/something}
url2 = {https://api.example.com/orgs/1/something}

• OS: Windows 11 25H2 26200.6899
• .NET version: 4.8.2
• Version 112.1.0

[gregveres]

Debugging, I see that the headers on the request have the following:

1. "UrlSegment providerOrgId=1"
2. "Header accept=application/json"
3. "UrlSegment providerOrgId=2"

I assume the bug is that Add isn't looking to see if there is already a UrlSegment for that parameter name.

[gregveres]

I have come up with a workaround to this unexpected behaviour.
You can remove the original parameter and add it again

var oldProvider = request.Parameters.FirstOrDefault(p => p.Type == ParameterType.UrlSegment && p.Name == "segment");
if (oldProvider != null) request.Parameters.RemoveParameter(oldProvider);
request.AddUrlSegment("segment", 2);

[alexeyzimarev]

You can just use AddOrUpdateParameter(new UrlSegmentParameter(...))

It's not really a bug. All AddParameter overloads and their derivatives add parameters. They don't look if the parameter with the same name was added before. That's what AddOrUpdate are for and normally it applies for headers, that's why AddOrUpdateHeader exist.

[alexeyzimarev]

But I'd say that for headers it makes sense because you can have multiple values for one header. For URL segments it's probably unclear as only the first value will be used anyway.

[alexeyzimarev]

Btw, this approach works well with query parameters too because we can add multiple query parameters with the same name. So, it looks like URL segment is the only outlier.