actix-web/actix-web/MIGRATION-4.0.md

Migrating to 4.0.0

It is assumed that migration is happening from v3.x. If migration from older version of Actix Web, see the other historical migration notes in this folder.

Headings marked with ⚠️ are breaking behavioral changes and will probably not surface as compile-time errors. Automated tests might detect their effects on your app.

Table of Contents:

• MSRV
• Module Structure

MSRV

The MSRV of Actix Web has been raised from 1.42 to 1.54.

Module Structure

Lots of modules has been organized in this release. If a compile error refers to "item XYZ not found in module..." or "module XYZ not found", refer to the documentation on docs.rs to to search for items' new locations.

⚠️ NormalizePath middleware

The default NormalizePath behavior now strips trailing slashes by default. This was previously documented to be the case in v3 but the behavior now matches. The effect is that routes defined with trailing slashes will become inaccessible when using NormalizePath::default(). As such, calling NormalizePath::default() will log a warning. It is advised that the new or trim methods be used instead.

Recommended Migration

- #[get("/test/")]`
+ #[get("/test")]`
  async fn handler() {

  App::new()
-   .wrap(NormalizePath::default())`
+   .wrap(NormalizePath::trim())`

Alternatively, explicitly require trailing slashes: NormalizePath::new(TrailingSlash::Always).

FromRequest Trait

The associated type Config of FromRequest was removed. If you have custom extractors, you can just remove this implementation and refer to config types directly, if required.

Recommended Migration

  impl FromRequest for MyExtractor {
-   `type Config = ();`
  }

Compression Feature Flags

Feature flag compress has been split into its supported algorithm (brotli, gzip, zstd). By default, all compression algorithms are enabled. The new flags are:

• compress-brotli
• compress-gzip
• compress-zstd

If you have set in your Cargo.toml dedicated actix-web features and you still want to have compression enabled.

web::Path

The inner field for web::Path was made private because It was causing too many issues when used with inner tuple types due to its Deref impl.

Recommended Migration

- async fn handler(web::Path((foo, bar)): web::Path<(String, String)>) {
+ async fn handler(params: web::Path<(String, String)>) {
+   let (foo, bar) = params.into_inner();

Rustls Crate Upgrade

Required version of rustls dependency was bumped to the latest version 0.20. As a result, the new server config builder has changed. See the updated example project →.