How to use serde_json in pallet?

Question

On using serde_json in my pallet dependency it throws this throws these error:- ``

  #[weight=10_000]
    pub fn insert_data_class(origin,app_id:Vec<u8>,db_id:Vec<u8>,cid:Vec<u8>,data:Vec<u8>,signature:H512)->DispatchResult{
        let caller = ensure_signed(origin)?;
        let app_data = alioth_register::Module::<T>::check_ownership(&caller,&app_id);
        ensure!(app_data.0,Error::<T>::AppNotFound);
        let data_str = String::from_utf8(data.clone()).unwrap();
        let data_json = json!(data_str);
        let uid:Vec<u8> = data_json["uid"].to_string().as_bytes().to_vec();
        //let uuid_str = data_json["uuid"].to_string();
        let uuid:Vec<u8> = data_json["uuid"].to_string().as_bytes().to_vec();
        let  data1 = data.clone();
        let data1 = String::from_utf8(data1).unwrap();
        let user_data = alioth_users::Module::<T>::check_user_extern(&uuid,&app_id);
        ensure!(user_data.0,Error::<T>::UserNotFound);
        let class_data = alioth_class::Module::<T>::check_class(&db_id,&cid);
        ensure!(class_data.0,Error::<T>::ClassOrDatabaseNotFound);
        //I needed a public key for this purpose we are going to write a function in alioth-users
        let pub_key_ref:(bool,H256) = alioth_users::Module::<T>::get_public_key(&uuid,&app_id);
        ensure!(pub_key_ref.0,Error::<T>::ObjectNotCreated);

        //now we are going to verify the signature for the further transaction
        ensure!(sp_io::crypto::sr25519_verify(&Signature::from_h512(signature),data1.as_bytes(),&Public::from_h256(pub_key_ref.1)),Error::<T>::SignatureNotVerified);
        //its over now we are going ahead to check the uniqness of data and insert it later.
        let data_from_self = Self::check_obj_store(&uid,&cid);
        ensure!(!data_from_self.0,Error::<T>::DataIsNotUnique);
        let struct_data = ObjectData{
            duid:uid,
            object:data,
        };
        if data_from_self.1==0{
            let vec_data = vec![struct_data];
            <ObjectStore>::insert(cid,vec_data);
            Self::deposit_event(Event::ObjectCreated());
        }
        else{
            let mut vec_data = <ObjectStore>::get(&cid);
            vec_data.insert(vec_data.len(),struct_data);
            <ObjectStore>::insert(cid,vec_data);
            Self::deposit_event(Event::ObjectCreated());
        }
        Ok(())
    }**this code uses serde_json::json macro**

error: failed to run custom build command for node-template-runtime v3.0.0 (/home/corteri/Desktop/blockchain/new_tmp/substrate-node-template/runtime)

Caused by: process didn't exit successfully: /home/corteri/Desktop/blockchain/new_tmp/substrate-node-template/target/debug/build/node-template-runtime-e56bc02a2834241f/build-script-build (exit status: 1) --- stdout Information that should be included in a bug report. Executing build command: "rustup" "run" "nightly" "cargo" "-Zfeatures=build_dep" "rustc" "--target=wasm32-unknown-unknown" "--manifest-path=/home/corteri/Desktop/blockchain/new_tmp/substrate-node-template/target/debug/wbuild/node-template-runtime/Cargo.toml" "--color=always" "--release" Using rustc version: rustc 1.56.0-nightly (b7404c898 2021-09-03)

--- stderr warning: flag -Z features has been stabilized in the 1.51 release, and is no longer necessary The new feature resolver is now available by specifying resolver = "2" in Cargo.toml. See https://doc.rust-lang.org/nightly/cargo/reference/features.html#feature-resolver-version-2 for more information.

 Compiling getrandom v0.2.1

error: target is not supported, for more information see: https://docs.rs/getrandom/#unsupported-targets --> /home/corteri/.cargo/registry/src/github.com-1ecc6299db9ec823/getrandom-0.2.1/src/lib.rs:214:9 | 214 | / compile_error!("target is not supported, for more information see:
215 | | https://docs.rs/getrandom/#unsupported-targets"); | |_________________________________________________________________________^

error[E0433]: failed to resolve: use of undeclared crate or module imp --> /home/corteri/.cargo/registry/src/github.com-1ecc6299db9ec823/getrandom-0.2.1/src/lib.rs:236:5 | 236 | imp::getrandom_inner(dest) | ^^^ use of undeclared crate or module imp

For more information about this error, try rustc --explain E0433. error: could not compile getrandom due to 2 previous errors

please include the code which you added when you first saw this error. Does it build when you remove it? — Simson
@Simson sir it builds after removing the serde_json dependency from Cargo.toml , — Aaditya Srivastava
@Simson sir I the error resolved but the problem is I am serde_json_core does not solves my problem because in extrinsics I don't know about json structure what user will send , but I know only two things that user's json data will contain uuid key, please help me by telling how to access value of uuid using serde_json_core like I did here-- — Aaditya Srivastava
let uuid:Vec<u8> = data_json["uuid"].to_string().as_bytes().to_vec(); — Aaditya Srivastava

Squirrel Squirrel · Accepted Answer · 2021-09-06T07:28:41

getrandom/js feature needs to be activated in your Cargo.toml:

# We enable it only for web-wasm check
# See https://docs.rs/getrandom/0.2.1/getrandom/#webassembly-support
getrandom = { version = "0.2", features = ["js"] }

(I don't think this is a serde_json specific error btw)

How to use serde_json in pallet?

1 Answers