Page MenuHomeDevCentral
Files F12241479

replies.rs
No OneTemporary
Actions

replies.rs
View Options

//! # API standard and JSON responses.
//!
//! This module provides useful traits and methods to craft API replies from an existing type.
use std::error::Error;
use diesel::result::DatabaseErrorInformation;
use diesel::result::DatabaseErrorKind;
use diesel::result::Error as ResultError;
use diesel::result::QueryResult;
use rocket::http::Status;
use rocket::response::Failure;
use rocket_contrib::Json;
/* -------------------------------------------------------------
Custom types
- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - */
pub type ApiJsonResponse<T> = Result<Json<T>, Failure>;
/* -------------------------------------------------------------
API Response
:: Implementation for QueryResult (Diesel ORM)
- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - */
/// This trait allows to consume an object into an HTTP response.
pub trait ApiResponse<T> {
/// Consumes the value and creates a JSON or a Failure result response.
fn into_json_response(self) -> ApiJsonResponse<T>;
}
impl<T> ApiResponse<T> for QueryResult<T> {
/// Prepares an API response from a query result.
///
/// The result is the data structure prepared by the Diesel ORM after a SELECT query
/// with one result, for example using `first` method. You can also you use it to
/// parse the returning result (... RETURNING *), which is a default for Diesel after
/// an INSERT query.
///
/// So result can be:
/// - Ok(T)
/// - Err(any database error)
///
/// # Examples
///
/// To offer a /player/foo route to serve player information from the player table:
///
/// ```
/// use limiting_factor::api::ApiResponse;
/// use limiting_factor::api::ApiJsonResponse;
///
/// #[get("/player/<name>")]
/// pub fn get_player(connection: DatabaseConnection, name: String) -> ApiJsonResponse<Player> {
/// players
/// .filter(username.eq(&name))
/// .first::<Player>(&*connection)
/// .into_json_response()
/// }
/// ```
///
/// This will produce a JSON representation when the result is found,
/// a 404 error when no result is found, a 500 error if there is a database issue.
fn into_json_response(self) -> ApiJsonResponse<T> {
match self {
// CASE I - The query returns one value, we return a JSON representation fo the item
Ok(item) => Ok(Json(item)),
Err(error) => match error {
// Case II - The query returns no result, we return a 404 Not found response
ResultError::NotFound => Err(Failure::from(Status::NotFound)),
// Case III - We need to handle a database error, which could be a 400/409/500
ResultError::DatabaseError(kind, details) => Err(build_database_error_response(kind, details)),
// Case IV - The error is probably server responsbility, log it and throw a 500
_ => Err(error.into_failure_response()),
}
}
}
}
/* -------------------------------------------------------------
Failure response
:: Implementation for diesel::result::Error
- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - */
/// This trait allows to consume an object into an HTTP failure response.
pub trait FailureResponse {
/// Consumes the variable and creates a Failure response .
fn into_failure_response(self) -> Failure;
}
impl FailureResponse for ResultError {
/// Consumes the error and creates a Failure 500 Internal server error response.
fn into_failure_response(self) -> Failure {
build_internal_server_error_response(self.description())
}
}
/* -------------------------------------------------------------
Helper methods to prepare API responses
- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - */
pub fn build_internal_server_error_response(message: &str) -> Failure {
warn!(target:"api", "{}", message);
Failure::from(Status::InternalServerError)
}
fn build_database_error_response(error_kind: DatabaseErrorKind, info: Box<dyn DatabaseErrorInformation>) -> Failure {
match error_kind {
// Case IIIa - The query tries to do an INSERT violating an unique constraint
// e.g. two INSERT with the same unique value
// We return a 409 Conflict
DatabaseErrorKind::UniqueViolation => Failure::from(Status::Conflict),
// Case IIIb - The query violated a foreign key constraint
// e.g. an INSERT referring to a non existing user 1004
// when there is no id 1004 in users table
// We return a 400 Bad request
DatabaseErrorKind::ForeignKeyViolation => Failure::from(Status::BadRequest),
// Case IIIc - For other databases errors, the client responsibility isn't involved.
_ => build_internal_server_error_response(info.message()),
}
}

File Metadata

Mime Type
text/plain
Expires
Sun, Oct 12, 05:21 (23 h, 29 m)
Storage Engine
blob
Storage Format
Raw Data
Storage Handle
3065123
Default Alt Text
replies.rs (4 KB)

Event Timeline

Nasqueron DevCentral · If it had been much bigger the moon would have had a core of ice. · Powered by Phabricator