Estimating contract call cost

With the function estimate_transaction_cost(tolerance: Option<f64>, block_horizon: Option<u32>) provided by CallHandler, you can get a cost estimation for a specific call. The return type, TransactionCost, is a struct that contains relevant information for the estimation:

pub struct TransactionCost {
    pub gas_price: u64,
    pub gas_used: u64,
    pub metered_bytes_size: u64,
    pub total_fee: u64,
}

Below are examples that show how to get the estimated transaction cost from single and multi call transactions.

        let contract_instance = MyContract::new(contract_id, wallet);

        let tolerance = Some(0.0);
        let block_horizon = Some(1);
        let transaction_cost = contract_instance
            .methods()
            .initialize_counter(42) // Build the ABI call
            .estimate_transaction_cost(tolerance, block_horizon) // Get estimated transaction cost
            .await?;

        let call_handler_1 = contract_methods.initialize_counter(42);
        let call_handler_2 = contract_methods.get_array([42; 2]);

        let multi_call_handler = CallHandler::new_multi_call(wallet.clone())
            .add_call(call_handler_1)
            .add_call(call_handler_2);

        let tolerance = Some(0.0);
        let block_horizon = Some(1);
        let transaction_cost = multi_call_handler
            .estimate_transaction_cost(tolerance, block_horizon) // Get estimated transaction cost
            .await?;

The transaction cost estimation can be used to set the gas limit for an actual call, or to show the user the estimated cost.

Note The same estimation interface is available for scripts.