Custom RPC parameters

Question

I'm trying to return an item that is within a storageMap. Its key is a Vec(u8), but I don't know how to send this type using a curl call. I tried using the id as string and using its hex version and I receive de following message:

~ % curl -H "Content-Type: application/json" -d '{"id":1, "jsonrpc":"2.0", "method": "items_getItemById", "params": [1234321] }' http://localhost:9933

{"jsonrpc":"2.0","error":{"code":-32602,"message":"Invalid params: invalid type: integer `1234321`, expected a (both 0x-prefixed or not) hex string with length of 64."},"id":1}

~ % curl -H "Content-Type: application/json" -d '{"id":1, "jsonrpc":"2.0", "method": "items_getItemById", "params": [0x31323334333231] }' http://localhost:9933

{"jsonrpc":"2.0","error":{"code":-32700,"message":"Parse error"},"id":null}

This is the item stored on chain:

[
  [
    [
      1234321
    ]
    {
      id: 1234321
      summary: 12341234
      owner: 5GrwvaEF5zXb26Fz9rcQpDWS57CtERHpNehXCPcNoHGKutQY
      state: ForSale
      price: 23
      lastUpdate: 1234123
      creationBlock: 4
    }
  ]
]

The main issue is that I'm not able to query the item from the following function:

pub fn get_item(id: ProductId) -> Option<ItemRpc> {
    Self::get_item_by_id(&id)
} 

fn get_item_by_id(id: &[u8]) -> Option<ItemRpc> {
    if let Some(value) = Self::items(id) {
        Some(value.to_rpc())
    } else {
        None
    }
}

This is how I create items for the pallet:

UPDATE

This is my rpc and my runtime api for the items pallet:

rpc:

fn get_item(
        &self,
        at: Option<<Block as BlockT>::Hash>,
        id: ProductId
    ) -> Result<Option<ItemRpc>> {
        let api = self.client.runtime_api();
        let at = BlockId::hash(at.unwrap_or_else(||
            // If the block hash is not supplied assume the best block.
            self.client.info().best_hash));

        let runtime_api_result = api.get_item(&at, id);
        runtime_api_result.map_err(|e| RpcError {
            code: ErrorCode::ServerError(9876), // No real reason for this value
            message: "Something wrong".into(),
            data: Some(format!("{:?}", e).into()),
        })
    }

runtime-api:

fn get_item(id: ProductId) -> Option<ItemRpc>;

node runtime:

impl_runtime_apis! {
    fn get_item(id: ProductId) -> Option<ItemRpc> {
        Items::get_item(id)
    }
}

ItemRpc struct:

pub struct ItemRpc {
        pub id: ProductId, // Vec<u8>
        pub summary: H256, // Vec<u8>
        pub owner: [u8; 32],
        pub state: State,
        pub price: Option<u32>,
        pub last_update: Timestamp, // Vec<u8>
        pub creation_block: u32,
    }

Answer 1

I had the same issue and it answered here. You need to add one more param for Option<BlockHash>

I believe you can try this,

curl -H "Content-Type: application/json" -d '{"id":1, "jsonrpc":"2.0", "method": "items_getItemById", "params": [null, 1234321] }' http://localhost:9933

Answer 2

After a few attempts, the only way to make it work was to supply an array of bytes but using ASCII encoding.

Example to query item with id '1234':

~ % curl -H "Content-Type: application/json" -d '{"id":1, "jsonrpc":"2.0", "method": "items_getItemById", "params": [null, [49, 50, 51, 52]] }' http://localhost:9933

After making this work, I was able to query multiple items (1234, 1762) providing a vector of bytes like

"params": [null, [[49, 50, 51, 52], [49, 55, 54, 50]]]