Project 021 – CRUD Operations on a Text File

What I Built

A CLI-based Rust app that performs Create, Read, Update, and Delete operations on a plain text file.

What I Learned

• I learned how to use std::fs and BufReader to manage file content line-by-line—great for simulating basic text-based databases.
• While Debug trait (derived with #[derive(Debug)]) is good for developers during debugging, Display is meant for end-users. It provides cleaner, more readable messages.

In Code:

impl fmt::Display for CrudError {
    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
        match self {
            CrudError::Io(e) => write!(f, "I/O error: {}", e),
            CrudError::InvalidLineNumber => write!(f, "Invalid line number"),
            CrudError::FileNotFound => write!(f, "File not found"),
        }
    }
}

This implementation means:

• When an I/O error occurs, it will show "I/O error: " followed by the specific OS error

• For invalid line numbers, a simple "Invalid line number" message

• For missing files, "File not found"

When this error handling is used in main():

match db.read() {
    Ok(lines) => { /* show content */ },
    Err(CrudError::FileNotFound) => println!("📭 File not found"),
    Err(e) => return Err(e),
}

Notes