Add a separate trait for optional extractors #2475

jplatte · 2023-12-30T22:10:51Z

Motivation

Closes #2298.

Solution

Add OptionalFromRequest, OptionalFromRequestParts
- Q: Should the trait items have different names from the ones in the non-optional traits?
Implement for relevant types
Deprecate OptionalFoo extractors
Documentation
Changelog

… and deprecate OptionalPath.

… and deprecate OptionalQuery.

jplatte · 2024-01-18T20:23:13Z

@davidpdrsn Have you had time to take a look? The main changes are done, and I don't want to do the remaining docs / changelog writing and cleanup if it's not yet clear whether this will be merged.

jplatte · 2024-03-14T20:26:31Z

@mladedav @yanns both of you have been active with contributions recently. Would you be up for reviewing this? For context, see the linked issue.

mladedav

One thing that bugs me is that the optional variants use the same rejections so for example if someone uses the optional typed header there still is valid representation in the rejection. for the missing case.

That said the rejections are non exhaustive so they cannot handle explicitly everything so they may omit this one as well. It might just be confusing.

I will read it more thoroughly tomorrow or over the weekend, but it makes sense as a whole.

I want to think on other ways to make the option work but on a first sight this may be the best solution.

mladedav · 2024-03-14T23:19:34Z

axum-extra/src/extract/query.rs

@@ -152,9 +174,11 @@ impl std::error::Error for QueryRejection {
 ///
 /// [example]: https://github.com/tokio-rs/axum/blob/main/examples/query-params-with-empty-strings/src/main.rs
 #[cfg_attr(docsrs, doc(cfg(feature = "query")))]
+#[deprecated = "Use Option<Path<_>> instead"]


Query instead of Path

mladedav

The code looks good to me.

The drawback I see here is having two distinct traits so it might be harder for users to discover how to properly use Options. That said in hindsight, it might be better to force users to use Result instead of Option if they really mean to just discard any errors.

I am still unsure about whether it is better to use the same rejections for optional and normal extractors if the missing case is already handled in the normal rejection. I think we could use some kind of enum (probably very similar to Option) for extractors that have optional variants. But each extractor would have to define IntoResponse for its missing case.

I also wonder if we couldn't get away with just one FromRequestParts trait where the extracting method would return an enum with three cases like MyResult<T, T::Missing, T::Rejection>. Then we could maybe create the extractors with correct semantics without the need for multiple traits.

But if that's not possible or having the two traits is a better tradeoff than whatever issues that potential solution has, the implementation as is looks ok. I think we should just go over the implementations of FromRequest and FromRequstParts and add a few implementations for the optional conterparts.

mladedav · 2024-03-16T19:11:09Z

axum-extra/src/extract/query.rs

 #[derive(Debug, Clone, Copy, Default)]
 pub struct OptionalQuery<T>(pub Option<T>);

+#[allow(deprecated)]


OptionalPath became this:

parts .extract::<Option<Path<T>>>() .await .map(|opt| Self(opt.map(|Path(x)| x)))

I think that a similar thing can be done here.

mladedav · 2024-03-16T19:40:09Z

axum-macros/tests/typed_path/pass/option_result.rs

 use axum::{extract::rejection::PathRejection, http::StatusCode};
+use axum_extra::routing::{RouterExt, TypedPath};


Nit, this change seems that the uses were just reordered.

mladedav · 2024-03-16T19:55:08Z

axum-macros/tests/typed_path/pass/option_result.rs

-async fn option_handler(_: Option<UsersShow>) {}
-


I think this should also be derived and usable.

mladedav · 2024-03-16T20:05:57Z

axum/src/extract/matched_path.rs

+where
+    S: Send + Sync,
+{
+    type Rejection = MatchedPathRejection;


I think this should be Infallible as missing is the only failure case.

And just to be sure, it seems to me like the only way MatchedPath would be missing is if it is accessed inside a fallback handler? If that's so, I think it would be better not to add this impl and have users just use Result if they want to guard against using it there.

mladedav · 2024-03-16T20:29:22Z

examples/todos/src/main.rs

@@ -82,13 +82,11 @@ pub struct Pagination {
 }

 async fn todos_index(
-    pagination: Option<Query<Pagination>>,
+    Query(pagination): Query<Pagination>,


This should not change I think.

Ah, this was intentional but I guess it should really be a separate PR with its own description.

jplatte · 2024-11-17T21:45:45Z

Damn, I didn't realize I failed to respond to most of the feedback here since asking for it. I definitely think having more specific rejection types would be better. I think it's something I skipped initially because it was just easier that way for the first prototype.

I'll try to make some time to back to this soon-ish.

jplatte requested a review from davidpdrsn December 30, 2023 22:10

jplatte force-pushed the jplatte/optional-from-request branch 2 times, most recently from d988573 to 91fabd2 Compare December 30, 2023 22:19

jplatte added 3 commits December 30, 2023 23:38

Add a separate trait for optional extractors

265e65a

Implement OptionalFromRequestParts for Path<T>

a654c89

… and deprecate OptionalPath.

Implement OptionalFromRequestParts for axum-extra's Query<T>

b8f499e

… and deprecate OptionalQuery.

jplatte force-pushed the jplatte/optional-from-request branch from 91fabd2 to b8f499e Compare December 30, 2023 22:38

jplatte added this to the 0.8 milestone Dec 30, 2023

jplatte added C-cleanup Category: PRs that clean code up or issues documenting cleanup. breaking change A PR that makes a breaking change. A-axum-core labels Dec 30, 2023

Fix nightly tests?

226a27e

mladedav reviewed Mar 14, 2024

View reviewed changes

mladedav reviewed Mar 16, 2024

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jplatte mentioned this pull request Apr 7, 2024

Stricter optional extractors #1883

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mladedav mentioned this pull request Aug 9, 2024

Drop IntoResponse trait requirement from FromRequestParts and FromRequest Rejections #2869

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jplatte mentioned this pull request Oct 8, 2024

Fallible handlers for custom rejections #2965

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Add a separate trait for optional extractors #2475

Add a separate trait for optional extractors #2475

jplatte commented Dec 30, 2023

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jplatte commented Nov 17, 2024 •

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		use axum::{extract::rejection::PathRejection, http::StatusCode};
		use axum_extra::routing::{RouterExt, TypedPath};

Add a separate trait for optional extractors #2475

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Add a separate trait for optional extractors #2475

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jplatte commented Dec 30, 2023

Motivation

Solution

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