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Many APIs document their methods with a lightweight template mechanism that looks like GET /user/{user} or POST /organisation/:org. This function makes it easy to copy and paste such snippets and retrieve template variables either from function arguments or the current environment.

req_template() will append to the existing path so that you can set a base url in the initial request(). This means that you'll generally want to avoid multiple req_template() calls on the same request.


req_template(req, template, ..., .env = parent.frame())



A request.


A template string which consists of a optional HTTP method and a path containing variables labelled like either :foo or {foo}.


Template variables.


Environment in which to look for template variables not found in .... Expert use only.


A modified HTTP request.


httpbin <- request(example_url())

# You can supply template parameters in `...`
httpbin |> req_template("GET /bytes/{n}", n = 100)
#> <httr2_request>
#> GET
#> Body: empty

# or you retrieve from the current environment
n <- 200
httpbin |> req_template("GET /bytes/{n}")
#> <httr2_request>
#> GET
#> Body: empty

# Existing path is preserved:
httpbin_test <- request(example_url()) |> req_url_path("/test")
name <- "id"
value <- "a3fWa"
httpbin_test |> req_template("GET /set/{name}/{value}")
#> <httr2_request>
#> GET
#> Body: empty