How should I get a copy of this object in rust? - rust

Question

I've got a small program that is supposed to print out the response status of an html get request and also print out the raw html of that response. (I am using the latest version of the reqwest crate for this)
fn main() {
let req = reqwest::blocking::get("https://www.rust-lang.org");
let rawhtml = req.clone().unwrap().text().unwrap();
let status = req.unwrap().status();
println!("status: {}\n\n", status);
println!("{}", rawhtml);
}
running with cargo run gives me error[E0599] saying
method cannot be called on Result<reqwest::blocking::Response, reqwest::Error> due to unsatisfied trait bounds
So if I cannot clone the object then how am I to use more than one of its functions that consumes "self"? I don't want to have to make multiple get requests when all the info I need should be in one.

Answer 1

First of all, reqwest::blocking::Response doesn't implement Clone or provide an alternative, so "getting a copy" is not an option; you need to structure your program so it doesn't need a copy.
The problem you're having with your current code is not mainly with the Response; it's that you're calling Result::unwrap, which does consume the Result it's called on — in order to give you its contents. The right thing to do here is to call unwrap only once.
let req = reqwest::blocking::get("https://www.rust-lang.org")
.unwrap();
let rawhtml = req.text().unwrap();
let status = req.status();
This still won't compile, but that's because you are calling the methods in the wrong order: you must ask for whatever things you need from the headers of the response before using the body. This is not an arbitrary constraint; it's because HTTP gives you that information in that order, and so having the API work this way allows reqwest to not need to store the entire response as it is downloaded — the Response object is not just an unchanging data structure but actually represents the response as it is being sent to your computer.
This version will work:
let req = reqwest::blocking::get("https://www.rust-lang.org")
.unwrap();
let status = req.status();
let rawhtml = req.text().unwrap();
status and rawhtml both implement Clone, so you can keep those around and make copies as much as you need, unlike the Response.
(Disclaimer: I haven't actually used reqwest myself; this answer is based on reading the docs and source, and general Rust principles.)