`req_template` cannot mix templates with both colon (:) and curly brackets ({ })

[stefanedwards]

The Microsoft Graph API has some curious endpoints, one of which requires the use of colon (:)

GET /sites/{hostname}:/{server-relative-path}

https://learn.microsoft.com/en-us/graph/api/site-get?view=graph-rest-1.0&tabs=http#access-a-site-by-server-relative-url

req_template fails miserable, as it believes the template uses colon-placeholders - not curly bracket placeholders:

req_template(request("http://example.http.com"), "/sites/{hostname}:/{server-relative-path}")
Error in env_has(env, name, inherit = TRUE) : 
  attempt to use zero-length variable name

Suggested solutions:

1. Document this behaviour, most do.
2. In template_type swap two first if conditions, so curly brackets are checked first, then brackets. Downside: Using a template without placeholders, but with a colon in the path will still fail.
3. Check for :\\w+ in the grepl for colon, instead of just :.

I'll gladly make the changes and make a pull request.

[stefanedwards]

Workaround:

Provide the colon in a variable placeholder.

req_template(request("http://example.http.com"), "/sites/{hostname}{colon}/{server-relative-path}", colon = ":")

[hadley]

I think flipping the check for colon and braces templates should do the job.