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Smart contract interaction

Unity3d interaction with Smart Contracts using Coroutines and UnityWebRequests

In a similar way to the Nethereum smart contracts, Unity3d can use the contract deployment and function message definitions to interact with the blockchain together with Coroutines and the underlying UnityWebRequest. If you are targetting a framework > 4.6 the Nethereum “vanilla” library can also be used if the platform supports System.Net.Http.HttpClient together with async / await TPL calls, so there is no need for specific Unity3d documentation.

The net351 project sample can be found at https://github.com/Nethereum/Unity3dSimpleSample, and the net461 sample project can be found at https://github.com/Nethereum/Unity3dSimpleSampleNet461

This sample covers all the steps of smart contract integration using the ERC20 standard token.

Declare our smart contract definition

First step is to include our smart contract definition, this can be code generated using the vscode solidity extension or the console code generation tool.

//Deployment contract object definition
    public partial class EIP20Deployment : EIP20DeploymentBase
    {
        public EIP20Deployment() : base(BYTECODE) { }
        public EIP20Deployment(string byteCode) : base(byteCode) { }
    }



    public class EIP20DeploymentBase : ContractDeploymentMessage
    {
        public static string BYTECODE = "608060405234801561001057600080fd5b506040516107843803806107848339810160409081528151602080840151838501516060860151336000908152808552959095208490556002849055908501805193959094919391019161006991600391860190610096565b506004805460ff191660ff8416179055805161008c906005906020840190610096565b5050505050610131565b828054600181600116156101000203166002900490600052602060002090601f016020900481019282601f106100d757805160ff1916838001178555610104565b82800160010185558215610104579182015b828111156101045782518255916020019190600101906100e9565b50610110929150610114565b5090565b61012e91905b80821115610110576000815560010161011a565b90565b610644806101406000396000f3006080604052600436106100ae5763ffffffff7c010000000000000000000000000000000000000000000000000000000060003504166306fdde0381146100b3578063095ea7b31461013d57806318160ddd1461017557806323b872dd1461019c57806327e235e3146101c6578063313ce567146101e75780635c6581651461021257806370a082311461023957806395d89b411461025a578063a9059cbb1461026f578063dd62ed3e14610293575b600080fd5b3480156100bf57600080fd5b506100c86102ba565b6040805160208082528351818301528351919283929083019185019080838360005b838110156101025781810151838201526020016100ea565b50505050905090810190601f16801561012f5780820380516001836020036101000a031916815260200191505b509250505060405180910390f35b34801561014957600080fd5b50610161600160a060020a0360043516602435610348565b604080519115158252519081900360200190f35b34801561018157600080fd5b5061018a6103ae565b60408051918252519081900360200190f35b3480156101a857600080fd5b50610161600160a060020a03600435811690602435166044356103b4565b3480156101d257600080fd5b5061018a600160a060020a03600435166104b7565b3480156101f357600080fd5b506101fc6104c9565b6040805160ff9092168252519081900360200190f35b34801561021e57600080fd5b5061018a600160a060020a03600435811690602435166104d2565b34801561024557600080fd5b5061018a600160a060020a03600435166104ef565b34801561026657600080fd5b506100c861050a565b34801561027b57600080fd5b50610161600160a060020a0360043516602435610565565b34801561029f57600080fd5b5061018a600160a060020a03600435811690602435166105ed565b6003805460408051602060026001851615610100026000190190941693909304601f810184900484028201840190925281815292918301828280156103405780601f1061031557610100808354040283529160200191610340565b820191906000526020600020905b81548152906001019060200180831161032357829003601f168201915b505050505081565b336000818152600160209081526040808320600160a060020a038716808552908352818420869055815186815291519394909390927f8c5be1e5ebec7d5bd14f71427d1e84f3dd0314c0f7b2291e5b200ac8c7c3b925928290030190a350600192915050565b60025481565b600160a060020a03831660008181526001602090815260408083203384528252808320549383529082905281205490919083118015906103f45750828110155b15156103ff57600080fd5b600160a060020a038085166000908152602081905260408082208054870190559187168152208054849003905560001981101561046157600160a060020a03851660009081526001602090815260408083203384529091529020805484900390555b83600160a060020a031685600160a060020a03167fddf252ad1be2c89b69c2b068fc378daa952ba7f163c4a11628f55a4df523b3ef856040518082815260200191505060405180910390a3506001949350505050565b60006020819052908152604090205481565b60045460ff1681565b600160209081526000928352604080842090915290825290205481565b600160a060020a031660009081526020819052604090205490565b6005805460408051602060026001851615610100026000190190941693909304601f810184900484028201840190925281815292918301828280156103405780601f1061031557610100808354040283529160200191610340565b3360009081526020819052604081205482111561058157600080fd5b3360008181526020818152604080832080548790039055600160a060020a03871680845292819020805487019055805186815290519293927fddf252ad1be2c89b69c2b068fc378daa952ba7f163c4a11628f55a4df523b3ef929181900390910190a350600192915050565b600160a060020a039182166000908152600160209081526040808320939094168252919091522054905600a165627a7a7230582084c618322109054a21a57e27075384a6172ab854e4b2c2d35062a964a6bf593f0029";

        public EIP20DeploymentBase() : base(BYTECODE) { }

        public EIP20DeploymentBase(string byteCode) : base(byteCode) { }

        [Parameter("uint256", "_initialAmount", 1)]

        public BigInteger InitialAmount { get; set; }

        [Parameter("string", "_tokenName", 2)]

        public string TokenName { get; set; }

        [Parameter("uint8", "_decimalUnits", 3)]

        public byte DecimalUnits { get; set; }

        [Parameter("string", "_tokenSymbol", 4)]

        public string TokenSymbol { get; set; }

    }



    [Function("transfer", "bool")]
    public class TransferFunctionBase : FunctionMessage
    {
        [Parameter("address", "_to", 1)]
        public string To { get; set; }
        [Parameter("uint256", "_value", 2)]
        public BigInteger Value { get; set; }
    }



    public partial class TransferFunction : TransferFunctionBase
    {
    }

    [Function("balanceOf", "uint256")]
    public class BalanceOfFunction : FunctionMessage
    {
        [Parameter("address", "_owner", 1)]
        public string Owner { get; set; }
    }

    [FunctionOutput]
    public class BalanceOfFunctionOutput : IFunctionOutputDTO
    {
        [Parameter("uint256", 1)]
        public int Balance { get; set; }
    }

    [Event("Transfer")]
    public class TransferEventDTOBase : IEventDTO
    {
        [Parameter("address", "_from", 1, true)]
        public virtual string From { get; set; }

        [Parameter("address", "_to", 2, true)]
        public virtual string To { get; set; }

        [Parameter("uint256", "_value", 3, false)]
        public virtual BigInteger Value { get; set; }
    }

    public partial class TransferEventDTO : TransferEventDTOBase
    {
        public static EventABI GetEventABI()
        {
            return EventExtensions.GetEventABI<TransferEventDTO>();
        }
    }

Contract deployment

To deploy a smart contract we create a TransactionSignedUnityRequest with our url and signing information. Creating a new EIP20Deployment contract definition we set the constructor parameters and send the transaction. Finally we we create TransactionReceiptPollingRequest to poll for the transaction receipt and retrieve the newly deployed contract address from the transaction receipt.

        var url = "http://localhost:8545";
        var privateKey = "0xb5b1870957d373ef0eeffecc6e4812c0fd08f554b37b233526acc331bf1544f7";
        var account = "0x12890d2cce102216644c59daE5baed380d84830c";
        //initialising the transaction request sender

        var transactionRequest = new TransactionSignedUnityRequest(url, privateKey, account);

        var deployContract = new EIP20Deployment()
        {
            InitialAmount = 10000,
            FromAddress = account,
            TokenName = "TST",
            TokenSymbol = "TST"
        };

        //deploy the contract
        yield return transactionRequest.SignAndSendDeploymentContractTransaction<EIP20DeploymentBase>(deployContract);

        if (transactionRequest.Exception != null)
        {
            Debug.Log(transactionRequest.Exception.Message);
            yield break;
        }

        var transactionHash = transactionRequest.Result;
        Debug.Log("Deployment transaction hash:" + transactionHash);

        //create a poll to get the receipt when mined
        var transactionReceiptPolling = new TransactionReceiptPollingRequest(url);

        //checking every 2 seconds for the receipt
        yield return transactionReceiptPolling.PollForReceipt(transactionHash, 2);

        var deploymentReceipt = transactionReceiptPolling.Result;

        Debug.Log("Deployment contract address:" + deploymentReceipt.ContractAddress);

Query smart contract

To Query a smart contract we need to create a new QueryUnityRequest providing the FunctionType and ReturnType. We then will yield the Query and the query result Result object will provide us the Ouput of the contract already decoded.

 //Query request using our acccount and the contracts address (no parameters needed and default values)
        var queryRequest = new QueryUnityRequest<BalanceOfFunction, BalanceOfFunctionOutput>(url, account);
        yield return queryRequest.Query(new BalanceOfFunction(){Owner = account}, deploymentReceipt.ContractAddress);

        //Getting the dto response already decoded
        var dtoResult = queryRequest.Result;
        Debug.Log(dtoResult.Balance);

Transfer transaction

To send a transaction to interact with a smart contract has similar steps to the deployment. We first create a TransactionSignedUnityRequest and our Function including any parameters, once the transaction is send we poll for the transaction receipt which will confirm the success of the transaction.

Using the transaction receipt we can decoded any logs / events for that transaction.

 var transactionTransferRequest = new TransactionSignedUnityRequest(url, privateKey);
        var newAddress = "0xde0B295669a9FD93d5F28D9Ec85E40f4cb697BAe";


        var transactionMessage = new TransferFunction
        {
            FromAddress = account,
            To = newAddress,
            Value = 1000,
        };

        yield return transactionTransferRequest.SignAndSendTransaction(transactionMessage, deploymentReceipt.ContractAddress);
        var transactionTransferHash = transactionTransferRequest.Result;

        Debug.Log("Transfer txn hash:" + transactionHash);

        transactionReceiptPolling = new TransactionReceiptPollingRequest(url);
        yield return transactionReceiptPolling.PollForReceipt(transactionTransferHash, 2);
        var transferReceipt = transactionReceiptPolling.Result;

        var transferEvent = transferReceipt.DecodeAllEvents<TransferEventDTO>();
        Debug.Log("Transferd amount from event: " + transferEvent[0].Event.Value);

Logs and Events

To retrived the logs / events of a smart contract we use the EthGetLogsUnityRequest combined with a FilterInput specific to our Event. FilterInputs can be created using the EventDTO extension GetEventABI(). Once we have yield the request, we can decode all matching events using the Result.DecodeAllEvents, extension method.

        var getLogsRequest = new EthGetLogsUnityRequest(url);
        var eventTransfer = TransferEventDTO.GetEventABI();
        yield return getLogsRequest.SendRequest(eventTransfer.CreateFilterInput(deploymentReceipt.ContractAddress, account));
        var eventDecoded = getLogsRequest.Result.DecodeAllEvents<TransferEventDTO>();
        Debug.Log("Transferd amount from get logs event: " + eventDecoded[0].Event.Value);

Full sample

using System.Collections;
using System.Collections.Generic;
using System.Numerics;
using Nethereum.ABI.FunctionEncoding.Attributes;
using Nethereum.ABI.Model;
using Nethereum.Contracts;
using Nethereum.Contracts.CQS;
using Nethereum.Contracts.Extensions;
using Nethereum.JsonRpc.UnityClient;
using UnityEngine;


public class TokenDeployAndSend : MonoBehaviour {



    //Deployment contract object definition
    public partial class EIP20Deployment : EIP20DeploymentBase
    {
        public EIP20Deployment() : base(BYTECODE) { }
        public EIP20Deployment(string byteCode) : base(byteCode) { }
    }



    public class EIP20DeploymentBase : ContractDeploymentMessage
    {
        public static string BYTECODE = "608060405234801561001057600080fd5b506040516107843803806107848339810160409081528151602080840151838501516060860151336000908152808552959095208490556002849055908501805193959094919391019161006991600391860190610096565b506004805460ff191660ff8416179055805161008c906005906020840190610096565b5050505050610131565b828054600181600116156101000203166002900490600052602060002090601f016020900481019282601f106100d757805160ff1916838001178555610104565b82800160010185558215610104579182015b828111156101045782518255916020019190600101906100e9565b50610110929150610114565b5090565b61012e91905b80821115610110576000815560010161011a565b90565b610644806101406000396000f3006080604052600436106100ae5763ffffffff7c010000000000000000000000000000000000000000000000000000000060003504166306fdde0381146100b3578063095ea7b31461013d57806318160ddd1461017557806323b872dd1461019c57806327e235e3146101c6578063313ce567146101e75780635c6581651461021257806370a082311461023957806395d89b411461025a578063a9059cbb1461026f578063dd62ed3e14610293575b600080fd5b3480156100bf57600080fd5b506100c86102ba565b6040805160208082528351818301528351919283929083019185019080838360005b838110156101025781810151838201526020016100ea565b50505050905090810190601f16801561012f5780820380516001836020036101000a031916815260200191505b509250505060405180910390f35b34801561014957600080fd5b50610161600160a060020a0360043516602435610348565b604080519115158252519081900360200190f35b34801561018157600080fd5b5061018a6103ae565b60408051918252519081900360200190f35b3480156101a857600080fd5b50610161600160a060020a03600435811690602435166044356103b4565b3480156101d257600080fd5b5061018a600160a060020a03600435166104b7565b3480156101f357600080fd5b506101fc6104c9565b6040805160ff9092168252519081900360200190f35b34801561021e57600080fd5b5061018a600160a060020a03600435811690602435166104d2565b34801561024557600080fd5b5061018a600160a060020a03600435166104ef565b34801561026657600080fd5b506100c861050a565b34801561027b57600080fd5b50610161600160a060020a0360043516602435610565565b34801561029f57600080fd5b5061018a600160a060020a03600435811690602435166105ed565b6003805460408051602060026001851615610100026000190190941693909304601f810184900484028201840190925281815292918301828280156103405780601f1061031557610100808354040283529160200191610340565b820191906000526020600020905b81548152906001019060200180831161032357829003601f168201915b505050505081565b336000818152600160209081526040808320600160a060020a038716808552908352818420869055815186815291519394909390927f8c5be1e5ebec7d5bd14f71427d1e84f3dd0314c0f7b2291e5b200ac8c7c3b925928290030190a350600192915050565b60025481565b600160a060020a03831660008181526001602090815260408083203384528252808320549383529082905281205490919083118015906103f45750828110155b15156103ff57600080fd5b600160a060020a038085166000908152602081905260408082208054870190559187168152208054849003905560001981101561046157600160a060020a03851660009081526001602090815260408083203384529091529020805484900390555b83600160a060020a031685600160a060020a03167fddf252ad1be2c89b69c2b068fc378daa952ba7f163c4a11628f55a4df523b3ef856040518082815260200191505060405180910390a3506001949350505050565b60006020819052908152604090205481565b60045460ff1681565b600160209081526000928352604080842090915290825290205481565b600160a060020a031660009081526020819052604090205490565b6005805460408051602060026001851615610100026000190190941693909304601f810184900484028201840190925281815292918301828280156103405780601f1061031557610100808354040283529160200191610340565b3360009081526020819052604081205482111561058157600080fd5b3360008181526020818152604080832080548790039055600160a060020a03871680845292819020805487019055805186815290519293927fddf252ad1be2c89b69c2b068fc378daa952ba7f163c4a11628f55a4df523b3ef929181900390910190a350600192915050565b600160a060020a039182166000908152600160209081526040808320939094168252919091522054905600a165627a7a7230582084c618322109054a21a57e27075384a6172ab854e4b2c2d35062a964a6bf593f0029";

        public EIP20DeploymentBase() : base(BYTECODE) { }

        public EIP20DeploymentBase(string byteCode) : base(byteCode) { }

        [Parameter("uint256", "_initialAmount", 1)]

        public BigInteger InitialAmount { get; set; }

        [Parameter("string", "_tokenName", 2)]

        public string TokenName { get; set; }

        [Parameter("uint8", "_decimalUnits", 3)]

        public byte DecimalUnits { get; set; }

        [Parameter("string", "_tokenSymbol", 4)]

        public string TokenSymbol { get; set; }

    }



    [Function("transfer", "bool")]
    public class TransferFunctionBase : FunctionMessage
    {
        [Parameter("address", "_to", 1)]
        public string To { get; set; }
        [Parameter("uint256", "_value", 2)]
        public BigInteger Value { get; set; }
    }



    public partial class TransferFunction : TransferFunctionBase
    {
    }

    [Function("balanceOf", "uint256")]
    public class BalanceOfFunction : FunctionMessage
    {
        [Parameter("address", "_owner", 1)]
        public string Owner { get; set; }
    }

    [FunctionOutput]
    public class BalanceOfFunctionOutput : IFunctionOutputDTO
    {
        [Parameter("uint256", 1)]
        public int Balance { get; set; }
    }

    [Event("Transfer")]
    public class TransferEventDTOBase : IEventDTO
    {
        [Parameter("address", "_from", 1, true)]
        public virtual string From { get; set; }

        [Parameter("address", "_to", 2, true)]
        public virtual string To { get; set; }

        [Parameter("uint256", "_value", 3, false)]
        public virtual BigInteger Value { get; set; }
    }

    public partial class TransferEventDTO : TransferEventDTOBase
    {
        public static EventABI GetEventABI()
        {
            return EventExtensions.GetEventABI<TransferEventDTO>();
        }
    }



    // Use this for initialization
    void Start () {

       // StartCoroutine(DeployAndTransferToken());
    }


    //Sample of new features / requests
    public IEnumerator DeployAndTransferToken()
    {

        var url = "http://localhost:8545";
        var privateKey = "0xb5b1870957d373ef0eeffecc6e4812c0fd08f554b37b233526acc331bf1544f7";
        var account = "0x12890d2cce102216644c59daE5baed380d84830c";
        //initialising the transaction request sender

        var transactionRequest = new TransactionSignedUnityRequest(url, privateKey, account);

        var deployContract = new EIP20Deployment()
        {
            InitialAmount = 10000,
            FromAddress = account,
            TokenName = "TST",
            TokenSymbol = "TST"
        };

        //deploy the contract
        yield return transactionRequest.SignAndSendDeploymentContractTransaction<EIP20DeploymentBase>(deployContract);

        if (transactionRequest.Exception != null)
        {
            Debug.Log(transactionRequest.Exception.Message);
            yield break;
        }

        var transactionHash = transactionRequest.Result;
        Debug.Log("Deployment transaction hash:" + transactionHash);

        //create a poll to get the receipt when mined
        var transactionReceiptPolling = new TransactionReceiptPollingRequest(url);

        //checking every 2 seconds for the receipt
        yield return transactionReceiptPolling.PollForReceipt(transactionHash, 2);

        var deploymentReceipt = transactionReceiptPolling.Result;

        Debug.Log("Deployment contract address:" + deploymentReceipt.ContractAddress);

        //Query request using our acccount and the contracts address (no parameters needed and default values)
        var queryRequest = new QueryUnityRequest<BalanceOfFunction, BalanceOfFunctionOutput>(url, account);
        yield return queryRequest.Query(new BalanceOfFunction(){Owner = account}, deploymentReceipt.ContractAddress);

        //Getting the dto response already decoded
        var dtoResult = queryRequest.Result;
        Debug.Log(dtoResult.Balance);

        var transactionTransferRequest = new TransactionSignedUnityRequest(url, privateKey);
        var newAddress = "0xde0B295669a9FD93d5F28D9Ec85E40f4cb697BAe";


        var transactionMessage = new TransferFunction
        {
            FromAddress = account,
            To = newAddress,
            Value = 1000,
        };

        yield return transactionTransferRequest.SignAndSendTransaction(transactionMessage, deploymentReceipt.ContractAddress);
        var transactionTransferHash = transactionTransferRequest.Result;

        Debug.Log("Transfer txn hash:" + transactionHash);

        transactionReceiptPolling = new TransactionReceiptPollingRequest(url);
        yield return transactionReceiptPolling.PollForReceipt(transactionTransferHash, 2);
        var transferReceipt = transactionReceiptPolling.Result;

        var transferEvent = transferReceipt.DecodeAllEvents<TransferEventDTO>();
        Debug.Log("Transferd amount from event: " + transferEvent[0].Event.Value);

        var getLogsRequest = new EthGetLogsUnityRequest(url);
        var eventTransfer = TransferEventDTO.GetEventABI();
        yield return getLogsRequest.SendRequest(eventTransfer.CreateFilterInput(deploymentReceipt.ContractAddress, account));

        var eventDecoded = getLogsRequest.Result.DecodeAllEvents<TransferEventDTO>();
        Debug.Log("Transferd amount from get logs event: " + eventDecoded[0].Event.Value);

    }
}
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