#cosmwasm #terra #cosmwasm-contracts #bindings #module #smart-contracts #blockchain

terra-cosmwasm

Bindings for CosmWasm contracts to call into custom modules of Terra Core

18 releases (10 stable)

3.0.0-beta.0 Dec 27, 2021
2.2.0 Aug 6, 2021
2.1.0 Jun 29, 2021
1.2.4 Mar 17, 2021
1.1.0 Jul 31, 2020

#3 in #terra

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1,008 downloads per month
Used in 18 crates (17 directly)

Apache-2.0

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Terra Bindings for CosmWasm

​ This crate provides Terra-specific bindings to enable your CosmWasm smart contracts to interact with the Terra blockchain by exposing messages and queriers that can be emitted and used from within your contract. ​

Installation

​ Add the following to your smart contract's Cargo.toml: ​

[dependencies]
terra-cosmwasm = { version = "2.2" }

Contents

​ Currently, the Terra bindings include: ​

  • Query support for:
    • Market
      • swap rate between 2 currencies at market price
    • Treasury
      • current tax cap for a denomination
      • current tax rate
    • Oracle
      • exchange rates for the given base_denom / quote_denoms ​
  • Messages
    • MsgSwap
    • MsgSwapSend

Usage

Querying

​ In order to use the query functions enabled by the bindings, create a TerraQuerier instance within your contract logic -- in either init(), handle(), or query() entrypoints. You can access all the enabled queries through this object. ​

// src/contract.rs
use cosmwasm_std::Coin;
use terra_cosmwasm::{ TerraQuerier, SwapResponse, TaxRateResponse, TaxCapResponse, ExchangeRatesResponse };...// handler
pub fn try_something<S: Storage, A: Api, Q: Querier>(
    deps: &mut Extern<S, A, Q>,
    env: Env,
    offer: &Coin
) -> StdResult<HandleResponse> {
    let querier = TerraQuerier::new(&deps.querier);
    let swap_rate: SwapResponse = querier.query_swap(offer.clone(), "uusd")?;
    let tax_cap: TaxCapResponse = querier.query_tax_cap("usdr")?;
    let tax_rate: TaxRateResponse = querier.query_tax_rate()?;
    let exchange_rates: ExchangeRatesResponse = querier.query_exchange_rates("uusd", vec!["uluna", "ukrw"])?;
    ...
}

Creating Messages

NOTE: The Terra bindings do not cover messages that have already been implemented by the CosmWasm team, such as staking-related messages and fundamental ones like MsgSend. ​ You may want your contract to perform messages such as MsgSwap and MsgSwapSend operations at the end of its execution. To do this, create a message using the predefined functions: ​

  • create_swap_msg
  • create_swap_send_msg ​ And add it to the vector of messages in your HandleResponse before you return Ok. ​
use cosmwasm_std::CosmosMsg;
use terra_cosmwasm::{create_swap_msg, TerraMsgWrapper};...pub fn try_something<S: Storage, A: Api, Q: Querier>(
    deps: &mut Extern<S, A, Q>,
    env: Env,
    offer: &Coin
) -> StdResult<HandleResponse<TerraMsgWrapper>> {
    ...let msg: CosmosMsg<TerraMsgWrapper> = create_swap_msg(contract_addr, offer_coin, ask_denom);
    let res = HandleResponse {
        messages: vec![msg],
        log: vec![],
        data: None
    };
    Ok(res)
}

Dependencies

~3.5–5.5MB
~114K SLoC