masterror/examples/basic_usage.rs at main · RAprogramm/masterror · GitHub

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// SPDX-FileCopyrightText: 2025 RAprogramm <andrey.rozanov.vl@gmail.com>

// SPDX-License-Identifier: MIT

//! Basic usage example showing the simplest ways to create and use errors.

//!

//! Run with:

//! ```sh

//! cargo run --example basic_usage

//! ```

use masterror::{AppError, AppErrorKind, AppResult, field};

fn validate_age(age: i32) -> AppResult<()> {

masterror::ensure!(age >= 0, AppError::bad_request("Age cannot be negative"));

masterror::ensure!(age <= 150, AppError::bad_request("Age seems unrealistic"));

Ok(())

}

fn fetch_user(id: &str) -> AppResult<String> {

if id.is_empty() {

masterror::fail!(AppError::bad_request("User ID cannot be empty"));

}

if id == "404" {

return Err(AppError::not_found("User not found"));

}

Ok(format!("User {id}"))

}

fn process_request(user_id: &str, age: i32) -> AppResult<String> {

validate_age(age)?;

let user = fetch_user(user_id)?;

Ok(format!("{user} is {age} years old"))

}

fn database_operation() -> AppResult<()> {

let err = AppError::database_with_message("Connection failed")

.with_field(field::str("host", "localhost"))

.with_field(field::u64("port", 5432))

.with_field(field::duration(

"timeout",

std::time::Duration::from_secs(5)

));

Err(err)

}

fn main() {

println!("=== Basic Error Creation ===\n");

let err = AppError::new(AppErrorKind::BadRequest, "Invalid input");

println!("Simple error: {err}");

println!("Error kind: {:?}", err.kind);

println!("Error code: {:?}\n", err.code);

println!("=== Using ensure! macro ===\n");

match validate_age(-5) {

Ok(()) => println!("Age valid"),

Err(e) => println!("Validation failed: {e}")

}

match validate_age(200) {

Ok(()) => println!("Age valid"),

Err(e) => println!("Validation failed: {e}")

}

match validate_age(25) {

Ok(()) => println!("Age 25 is valid\n"),

Err(e) => println!("Validation failed: {e}")

}

println!("=== Using fail! macro ===\n");

match fetch_user("") {

Ok(user) => println!("Found: {user}"),

Err(e) => println!("Fetch failed: {e}")

}

match fetch_user("404") {

Ok(user) => println!("Found: {user}"),

Err(e) => println!("Fetch failed: {e}")

}

match fetch_user("alice") {

Ok(user) => println!("Found: {user}\n"),

Err(e) => println!("Fetch failed: {e}")

}

println!("=== Error Propagation ===\n");

match process_request("bob", 30) {

Ok(result) => println!("Success: {result}"),

Err(e) => println!("Request failed: {e}")

}

match process_request("404", 30) {

Ok(result) => println!("Success: {result}"),

Err(e) => println!("Request failed: {e}\n")

}

println!("=== Structured Metadata ===\n");

match database_operation() {

Ok(()) => println!("Database operation succeeded"),

Err(e) => {

println!("Database error: {e}");

println!("Metadata fields: {}", e.metadata().len());

for (key, value) in e.metadata().iter() {

println!(" {key}: {value:?}");

}

masterror/examples/basic_usage.rs at main · RAprogramm/masterror · GitHub

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