Cookbook and HowTo new validation system · Tuntii/RustAPI · Discussion #111

PeterGumball
Feb 9, 2026

Hello Tunay.

I'm back 😀 I was a bit ill. I saw that you've been very busy, respect.

I would like to use the "new" validation engine, but I find the description in the cookbook very "vague".

In the example code, i can see that you include rustapi_macros::Validate and use rustapi_validate::v2::{ValidationContext, RuleError}, but under "Troubleshooting: Common Gotchas/Use rustapi_rs, Not Internal Crates" in the cookbook that the internal crates should not be imported. That is totally confusing.

Do you have a working example somewhere?

Replies: 2 comments 21 replies

Tuntii
Feb 9, 2026
Maintainer

Hey! Welcome back, and sorry to hear you were ill. Hope you’re feeling better 🙏

Great question! you’re right that this is currently confusing.

Rule of thumb:

For app-facing API, use rustapi_rs (use rustapi_rs::prelude::*).
For the new validation derive, use #[derive(rustapi_macros::Validate)] (or #[derive(rustapi_rs::Validate)] if exposed in your setup).
For custom_async function signatures, you currently still need rustapi_validate::v2::{ValidationContext, RuleError}.

So "don’t import internal crates" is the general guidance, but validation v2 custom async is an exception right now.

Working examples in repo:

crates/rustapi-rs/tests/validation_tests.rs
crates/rustapi-validate/tests/custom_async.rs

Minimal working async example:

use rustapi_rs::prelude::*;
use rustapi_macros::Validate;
use rustapi_validate::v2::{ValidationContext, RuleError};
#[derive(Debug, Deserialize, Serialize, Validate)]
struct CreateUserRequest {
 #[validate(custom_async = "check_username")]
 username: String,
}
async fn check_username(v: &String, _ctx: &ValidationContext) -> Result<(), RuleError> {
 if v == "admin" {
 Err(RuleError::new("reserved", "This username is reserved"))
 } else {
 Ok(())
 }
}

3 replies

@PeterGumball

PeterGumball Feb 9, 2026
Author

Ok, will try it later. At the moment i update my client source.

Should i add rustapi-validate and rustapi-macros to the dependencies in cargo.toml?

@Tuntii

Tuntii Feb 9, 2026
Maintainer

If you use the facade style (rustapi_rs), keep only:

rustapi-rs in Cargo.toml

imports from rustapi_rs::prelude::*

derive as #[derive(rustapi_rs::Validate)] (or via prelude patterns)

Add rustapi-macros`` **only if** you explicitly write #[derive(rustapi_macros::Validate)].`

Add rustapi-validate only if you explicitly reference v2 types like rustapi_validate::v2::{ValidationContext, RuleError} (common in custom_async signatures right now).

So for a clean client API surface: start with just rustapi-rs add the others only when compiler asks for those direct paths.

@Tuntii

Tuntii Feb 9, 2026
Maintainer

By the way, I'm so glad you're back. I was bored without you <3

PeterGumball
Feb 10, 2026
Author

Hey Tunay.

I have add rustapi_rs::Validate to my struct.

Now i get the following error:

 󱞪 cargo build
 Compiling backend v0.1.0 (/Users/peter/Develop/rust/pg-social-backend)
error[E0433]: failed to resolve: could not find `rustapi_validate` in the list of imported crates
 --> src/features/pins/request.rs:5:47
 |
5 | #[derive(Debug, Deserialize, Schema, Default, rustapi_rs::Validate)]
 | ^^^^^^^^^^^^^^^^^^^^ could not find `rustapi_validate` in the list of imported crates
 |
 = note: this error originates in the derive macro `rustapi_rs::Validate` (in Nightly builds, run with -Z macro-backtrace for more info)
error[E0433]: failed to resolve: could not find `rustapi_core` in the list of imported crates
 --> src/features/pins/request.rs:5:47
 |
5 | #[derive(Debug, Deserialize, Schema, Default, rustapi_rs::Validate)]
 | ^^^^^^^^^^^^^^^^^^^^ could not find `rustapi_core` in the list of imported crates
 |
 = note: this error originates in the derive macro `rustapi_rs::Validate` (in Nightly builds, run with -Z macro-backtrace for more info)
error[E0433]: failed to resolve: could not find `rustapi_core` in the list of imported crates
 --> src/features/pins/request.rs:5:47
 |
5 | #[derive(Debug, Deserialize, Schema, Default, rustapi_rs::Validate)]
 | ^^^^^^^^^^^^^^^^^^^^ could not find `rustapi_core` in the list of imported crates
 |
 = note: this error originates in the derive macro `rustapi_rs::Validate` (in Nightly builds, run with -Z macro-backtrace for more info)

Otherwise, I haven't changed anything.