Sylvia
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attributessylvia

sv::messages attribute

Use sv::messages to expand your contract functionality with the Sylvia interface.

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The sv::messages attribute expects that the trait is implemented on the contract type.

Macros

List of macros supporting the sv::messages attribute:

Usage

pub mod interface {
    use cosmwasm_schema::cw_serde;
    use sylvia::cw_std::{Response, StdError, StdResult};
    use sylvia::interface;
    use sylvia::types::{ExecCtx, QueryCtx};
 
    #[cw_serde]
    pub struct InterfaceQueryResp {}
 
    #[interface]
    pub trait Interface {
        type Error: From<StdError>;
 
        #[sv::msg(exec)]
        fn interface_exec(&self, ctx: ExecCtx) -> StdResult<Response>;
 
        #[sv::msg(query)]
        fn interface_query(&self, ctx: QueryCtx) -> StdResult<InterfaceQueryResp>;
    }
}
 
pub mod contract {
    use cosmwasm_std::StdError;
    use sylvia::contract;
    use sylvia::cw_std::{Response, StdResult};
    use sylvia::types::{ExecCtx, InstantiateCtx, QueryCtx};
 
    use crate::interface::{Interface, InterfaceQueryResp};
 
    pub struct CounterContract;
 
    #[cfg_attr(feature = "library", sylvia::entry_points)]
    #[contract]
    #[sv::messages(crate::interface)]
    impl CounterContract {
        pub const fn new() -> Self {
            Self
        }
 
        #[sv::msg(instantiate)]
        fn instantiate(&self, ctx: InstantiateCtx) -> StdResult<Response> {
            Ok(Response::new())
        }
    }
 
    impl Interface for CounterContract {
        type Error = StdError;
 
        fn interface_exec(&self, ctx: ExecCtx) -> StdResult<Response> {
            // some code
        }
 
        fn interface_query(&self, ctx: QueryCtx) -> StdResult<InterfaceQueryResp> {
            // some code
        }
    }
}
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Single sv::messages attribute corresponds to a single interface implemented on a contract. If multiple interfaces are implemented, add this attribute for each of them.

Module/Interface name mismatch

In most cases, the only parameter the sv::messages expects is a path to the interface, in this case crate::interface. Sylvia macros can deduce the interface's name if it is simply an UpperCamelCase version of the module name.

If the interface name differs from the module name, use the syntax below:

#[sv::messages(crate::interface as OtherInterface)]

Custom types

It's possible to implement an interface using Empty (opens in a new tab) instead of custom types used in the contract.

In such a case, we must inform Sylvia to convert the types in the dispatch methods.

#[sv::messages(crate::interface: custom(msg, query))]

The order of msg and query doesn't matter, and the attribute accepts either msg, query or both.

ErrorMsg