Cache without key about cached HOT 7 CLOSED

Yeah, that's currently the best way - using bool and true might be more obvious to read though. We could probably add an arg to cached to have it set bool and true automatically for you. I'm not sure what the best way to express that would be...

#[cached(time = 5, key = None)]
#[cached(time = 5, no_key)]
#[cached(time = 5, keyless)]
#[cached(time = 5, always)]

from cached.

Not sure of the right syntax @jaemk but I tried

#[cached(time = 5, key = "bool", convert = r#"{ true }"#)]

I'm getting a lot of errors with this though, I'm guessing this doesn't really ignore the arguments? They still have to have Hash?

error[E0308]: mismatched types
  --> src/main.rs:11:1
   |
11 | #[cached(time = 5, key = "bool", convert = r#"{ true }"#)]
   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ expected enum `std::result::Result`, found reference
   |
   = note:   expected enum `std::result::Result<Vec<Alert>, reqwest::Error>`
           found reference `&std::result::Result<Vec<Alert>, reqwest::Error>`
   = note: this error originates in an attribute macro (in Nightly builds, run with -Z macro-backtrace for more info)

error[E0599]: no method named `clone` found for enum `std::result::Result<Vec<Alert>, reqwest::Error>` in the current scope
   --> src/main.rs:11:1
    |
11  |   #[cached(time = 5, key = "bool", convert = r#"{ true }"#)]
    |   ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ method not found in `std::result::Result<Vec<Alert>, reqwest::Error>`
    | 
   ::: /home/ecarroll/.cargo/registry/src/github.com-1ecc6299db9ec823/reqwest-0.11.1/src/error.rs:12:1
    |
12  |   pub struct Error {
    |   ---------------- doesn't satisfy `reqwest::Error: Clone`
    |
    = note: the method `clone` exists but the following trait bounds were not satisfied:
            `Vec<Alert>: Clone`
            which is required by `std::result::Result<Vec<Alert>, reqwest::Error>: Clone`
            `reqwest::Error: Clone`
            which is required by `std::result::Result<Vec<Alert>, reqwest::Error>: Clone`
    = note: this error originates in an attribute macro (in Nightly builds, run with -Z macro-backtrace for more info)

from cached.

I believe the error you're getting is because you need to add a result = true. The following

#[cached(time = 5, key = "bool", convert = r#"{ true }"#, result = true)]
async fn cached_test(s: String) -> std::result::Result<Vec<String>, &'static dyn std::error::Error> {
    Ok(vec![s])
}


println!("{:?}", cached_test("a".to_string()).await);
println!("{:?}", cached_test("definitely not a".to_string()).await);

prints out

Ok(["a"])
Ok(["a"])

from cached.

I actually tried #[cached(time = 5, key = None)] at first because it felt intuitive.

However, I'm starting to think that this is just an edge case of "I want to ingore this parameters" or "I just care about these parameters" which is already covered by key+convert. Maybe a more ergonomic addition would be to be able to select keys by name like:

#[cached(time = 5, keys = (a, b) )]
async fn something(db_pool: DBPool, a: String, b: String) -> Result<(), Error> {

I am not sure if that's how to do it in macro-land but it would be crystal clear to me as a user of the library. If there's a problem with mixing types I would certainly be ok with having to impl something like Hash on all keys so we get a tuple that's Hash (or a Unit in my no key case).

Anyway, thanks for a great lib!

from cached.

The tough part is being able to name the type that's the cache key, so while it's not as pretty as what you have there, I think this would work. Also the proc macro is using this crate https://docs.rs/darling/0.12.2/darling/ to parse the proc macro parameters, and one of the limitations is that the arguments need to be strings

#[cached(time = 5, key = "(String, String)", convert = r#"{ (a, b) }"#, result = true)]
async fn cached_test(a: String, b: String) -> std::result::Result<Vec<String>, &'static dyn std::error::Error> {
    Ok(vec![a])
}

from cached.

I believe the error you're getting is because you need to add a result = true. The following

#[cached(time = 5, key = "bool", convert = r#"{ true }"#, result = true)]
async fn cached_test(s: String) -> std::result::Result<Vec<String>, &'static dyn std::error::Error> {
    Ok(vec![s])
}


println!("{:?}", cached_test("a".to_string()).await);
println!("{:?}", cached_test("definitely not a".to_string()).await);

prints out

Ok(["a"])
Ok(["a"])

That gives me associated `static` items are not allowedrustc Any ideas?

from cached.

The #[once] macro was added back in October which I believe will do what you were asking for:

The arguments are passed through to your logic, but there is no "key" - it's only caching a singleton associated with the function.

from cached.