Attribute Macro post_process

#[post_process]

Define a post-processing middleware.

Example

Log the status code of the HTTP response returned to the caller:

use pavex::{post_process, Response};
use pavex_tracing::{
    RootSpan,
    fields::{http_response_status_code, HTTP_RESPONSE_STATUS_CODE}
};

#[post_process]
pub fn response_logger(response: Response, root_span: &RootSpan) -> Response
{
    root_span.record(
        HTTP_RESPONSE_STATUS_CODE,
        http_response_status_code(&response),
    );
    response
}

Guide

Check out the “Middlewares” section of Pavex’s guide for a thorough introduction to middlewares in Pavex applications.

Registration

Use Blueprint::post_process to register the middleware with your Blueprint.

The #[post_process] macro generates a constant that you can use to refer to the middleware when invoking Blueprint::post_process.

Arguments

The sections below provide an exhaustive list of all the arguments and flags supported by the post_process macro:

Name	Kind	Required
id	Argument	No

id

By default, Pavex generates a constant named after your function (converted to UPPER_SNAKE_CASE) that you use when registering the middleware.

The id argument allows you to customize the name of the generated constant.

Example

Using the default generated identifier:

use pavex::{post_process, Blueprint, Response};
use pavex_tracing::RootSpan;

#[post_process]
pub fn response_logger(response: Response, root_span: &RootSpan) -> Response
{
    // [...]
}

let mut bp = Blueprint::new();
// The generated constant is named `RESPONSE_LOGGER`
bp.post_process(RESPONSE_LOGGER);

Using a custom identifier:

use pavex::{post_process, Blueprint, Response};
use pavex_tracing::RootSpan;

#[post_process(id = "LOG_RESPONSE")]
//             👆 Custom identifier
pub fn response_logger(response: Response, root_span: &RootSpan) -> Response
{
    // [...]
}

let mut bp = Blueprint::new();
// Use the custom identifier when registering
bp.post_process(LOG_RESPONSE);