Subj : Re: Rust >.<
To   : apam
From : tenser
Date : Thu Oct 06 2022 07:22:55

On 05 Oct 2022 at 10:47p, apam pondered and said...
 
 ap> I'm trying to learn rust.. I'm stuck however and was hoping someone more
 ap> familiar with the language could tell me where I'm going wrong...

Sure!

 ap> I have a json file located in "users/apam.json"
 ap> 
 ap> I have a function to save the userfile (that worked great) however
 ap> loading it is causing me problems...
 ap> 
 ap> if I load it with :
 ap> 
 ap> let d = fs::read_to_string("users/".to_owned() + &username + ".json")?;

So a couple of things here....

First of all, there's a Path library with PathBuf that you
should use for this, instead of building up a string.

Second of all, have you tried `assert!()`'ing that the
file pathname you create is actually what you expect?

I can't reproduce this locally, though.  Copy/pasting
into `syncterm` is hard for reasons, but 

: chandra; mkdir users
: chandra; echo hi > users/apam.json
: chandra; cat src/main.rs
use std::fs;

fn main() {
    let username = "apam".to_string();
    let filename = "users/".to_owned() + &username + ".json";
    println!("{filename}");
    let d = fs::read_to_string("users/".to_owned() + &username + ".json").unwrap();
    println!("{d}");
}
: chandra; cargo run
    Finished dev [unoptimized + debuginfo] target(s) in 0.02s
     Running `target/debug/apam`
users/apam.json
hi

: chandra; 

 ap> where username is a string that contains "apam"
 ap> 
 ap> it fails with "os error, no such file or directory"

I think I'd try to capture the filename you think you
are creating and ensure that it matches what you expect,
either printing it, or in an `assert!()` (or, even better,
in a `#[test]`!).  Also ensure you are in the directory
you think you in, since you're opening a relative path?

 ap> if however I do this:
 ap> 
 ap> let d = fs::read_to_string("users/apam.json")?;
 ap> 
 ap> it works...
 ap> 
 ap> (yes I'm practicing rust by writing a toy bbs)

Cool.

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