find the name of a json file in rust

To find the name of a JSON file in Rust, you will need to use the std::fs module, which provides a collection of functions for interacting with the filesystem. Specifically, you can use the read_dir function to obtain a list of entries in a directory, and then iterate through each entry to find the JSON file you are looking for.

Here's an example that demonstrates this process:

main.rs
use std::fs;

fn find_json_file() -> Option<String> {
    let dir_entries = fs::read_dir(".")?;

    for entry in dir_entries {
        let path = entry?.path();
        if path.is_file() && path.extension().map_or(false, |ext| ext == "json") {
            return Some(path.to_str()?.to_owned());
        }
    }

    None
}
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This function uses the read_dir function to obtain a list of directory entries in the current directory. It then iterates over each entry and checks if it's a file and if it has a JSON extension. If it finds a JSON file, it returns its name as a String; otherwise, it returns None.

Note the use of ? to propagate any errors that may occur while reading the directory or converting the Path to a &str. This makes the function more robust and easier to read.