Has there been any progress on this since this was last asked?
This response by @chenyan has the last update that this was something being worked on.
The documentation here references this but wasn’t able to figure out how to set this up exactly
I also found these 2 pull requests that pertain to this discussion but haven’t been able to completely work out how to make this work
and
Any updates/thoughts?
Hey yeah we’ve been able to generate candid from rust for a while now. Not sure why it’s still kinda hidden from documentation. All the psychedelic projects use it ! You just need to add the CandidType derive, and the
candid_service(query/update/init) macro to all the methods and types that need to be exported. Then, the export_service!() macro will generate function that returns the candid from rust, which can be run differently depending on the project setup
For projects using a main.rs: You can add a main function only run when target is not wasm32. Then, running cargo run would print the candid, which can be easily piped to a file (cargo run > candid.did ). This works well with mono canister architechtures.
Example: nft-marketplace/main.rs at develop · Psychedelic/nft-marketplace · GitHub
for projects using cdylib/lib.rs: You can make a rust test called save_candid, which would save the candid to a file in the project root when running cargo test. This works really well for multi canister architectures.
Example: cap/lib.rs at main · Psychedelic/cap · GitHub
Personally, I’ve been moving solely to the lib.rs/rust test flow, to allow exporting multiple canisters did interfaces with a single command. If you have other tests as well, you can run only the candid tests using cargo test save_candid
We also plan on making this easy and automatic with the ic_kit - Rust, where we’d include the corresponding candid_method with the #[update/query/init] macro automatically
Thank you so much for the response.
With the mechanism that uses the test to generate the .did file, what is the value of CARGO_MANIFEST_DIR that you are passing in the code highlighted here?
Of course! Having auto generation makes work so much easier.
The cargo manifest dir is a environment variable provided (by cargo) during the test run, of the location of the crates cargo.toml. This is the crate toml, not the workspace, so we step back 2 parent directories to the project root, and place the candid in the candid/<name>.did
Right, I was asking what exact value you were passing.
I ended up shortening it further by doing it like this instead of relying on the env variable
Sorry, I had meant to add (but somehow didn’t) that it’s provided automatically by cargo
This is a good solution as well!
@chenyan It would sure be nice to not have to do these workarounds to get that file generated. I’d love dfx to do it for you
@oss so I assume you need to pass in the path to the generated Candid file in dfx.json? So for example, cargo test needs to run before installing the Wasm binary?
@lastmjs Exactly, I usually like having the step automatically done through a makefile (make build does the candid gen, then the dfx build).
Separately, we’re finding a solution with the kit to tie this all together. In 0.5, query/update/init macros automatically use the candid_method, as well as the candid being exported with a single macro at the end of your file. Ideally we’re looking for a solution to just do everything on compile, but already the process is 10x better
can this work for ic-cdk = “0.10.0” ?
I`m trying to generate did file for a half day .
Still like an ape in Space Odyssey.
The official doc is lake of that part on how to auto generate
did file for frontend canister use.
with 0.10.0, a new release came out that makes generating did for rust a lot easier.
it’s not yet fully integrated to dfx but already simplifies things a lot.
@peterparker is the author of the article. Maybe he has an open access link or a different version somewhere?
Indeed, here crossposted on my website: https://daviddalbusco.com/blog/automatic-candid-generation-in-rust-exploring-the-ic-cdk-v0-10-0-update/
Otherwise opening the Medium link in an incognito browser should do to.
