[Ethereum] Passing constructor arguments while deploying contract from byte code

constructorcontract-deploymentmyetherwallet

I am trying to deploy a contract via MyEtherWallet from byte code generated by browser-solidity. I unlocked my wallet using private key,but I didn't find any way of passing parameters to contract's constructor. How can I do that?

This makes me doubt whether I will be able to call all functions of my contract from MyEtherWallet as I was able to do using Mist.
I am using MyEtherWallet as substitue to Mist because it saves me from downloading blockchain data.But not sure whether this will work as substitue of Mist for deploying and accessing contracts.

Edit 1: Even on deploying contract from Mist using byte code doesn't give any option to choose for a contact and pass parameters to contract. While deploying contract from source code works as good as expected.

Best Answer

If you look at Web3's documentation, you can get the full deployment bytecode with:

var bytecodeWithParam = MyContract.new.getData(
    param1,
    param2,
    { data: compiledByteCode });

It is this bytecodeWithParam that you paste into the "Byte Code" field. If you look at it in detail, you will see param1 and param2 32-byte packed at the end.

Related Solutions

[Ethereum] Error: Identifier not found or not unique. when deploying a smart contract which calls another contract

I refer to your code for ItemListContract in Unable to add new struct item into mapping or array.

The following code compiles without errors:

pragma solidity ^0.4.0;

contract ItemListContract {
    struct item {
        bytes iname;
        uint16 itemid;
        bytes icode;
        uint ivalue;
    }

    uint itemCount;
    mapping(bytes => item) itemList;
    item[] itemArray;

    function ItemListContract() {
        log0('hi');
    }

    function addItem(bytes name, uint16 iid, bytes code, uint val) {        
        var itemnew = item(name, iid ,code, val);
        // log0(itemnew);
        itemList[code] = itemnew;
        itemArray.push(itemnew);
        itemCount++;
    }

    function countItemList() constant returns (uint count) {     
        return itemCount;
    }

    function removeItem(bytes code) {
        delete itemList[code];
        itemCount--;
    }

    function getItem(bytes code) constant returns (bytes iname, uint val) {   
        return (itemList[code].iname, itemList[code].ivalue);
    }
}

contract ItemListCallerContract {

     ItemListContract itemListContract;

     function ItemListCallerContract() {
         itemListContract = ItemListContract(0x16c5d0c8fccaf7e5824f5ae25c1662877cec6452);
     }

     function getItemCount() constant returns(uint count) {
         return itemListContract.countItemList();
     }
}

In your code, the compiler will need to know the code for ItemListContract. The address for the first contract is defined without the double quotes. I also had to change the getItemCount() return type to match that of ItemListContract.countItemList().

You can also just provide the interface for the first contract without the implementation details as shown below:

pragma solidity ^0.4.0;

contract ItemListContract {

    function ItemListContract();

    function addItem(bytes name, uint16 iid, bytes code, uint val);

    function countItemList() constant returns (uint count);

    function removeItem(bytes code);

    function getItem(bytes code) constant returns (bytes iname, uint val);
}

contract ItemListCallerContract {

     ItemListContract itemListContract;

     function ItemListCallerContract() {
         itemListContract = ItemListContract(0x16c5d0c8fccaf7e5824f5ae25c1662877cec6452);
     }

     function getItemCount() constant returns(uint count) {
         return itemListContract.countItemList();
     }
}

Contract Deployment – How to Deploy Contracts with Constructor Arguments via Geth RPC

It is quite complicated to get this correct, but here's some information on how to work it out.

I'm using a simple contract as an example:

pragma solidity ^0.4.2;

contract Test {
    uint256 public v1;
    string public v2;

    function Test(uint256 _v1, string _v2) {
        v1 = _v1;
        v2 = _v2;
    }
}

Here is my deployment to a --dev blockchain using Browser Solidity:

Here's the bytecode from the Browser Solidity:

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

Before deploying the contract to the --dev blockchain, I ran the command debug.verbosity(4) in the geth console command line. When Browser Solidity is deploying the contract, the following information is displayed in geth:

I1222 14:09:50.670663 core/tx_pool.go:542] Promoting queued transaction:

TX(92a1308637d6ad0a63b181194701114780afdaacfcd73604a1f7f3b6985b9755)

Contract: false

From: 000d1009bd8f0b1301cc5edc28ed1222a3ce671e

To: [contract creation]

Nonce: 457

GasPrice: 20000000000

GasLimit 198696

Value: 0

Data: 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

V: 0x1c

R: 0xe84786ff0c0ed7564a972d3e037ef74d9adada759f845f36246e818f987d2945

S: 0x38ce5aa5b1a283f3270acd4668e99d410cd7f65ac74f4ae72416b0068935bd51

Hex: f9030a8201c98504a817c800830308288080b902b56060604052604051610235380380610235833981016040528051608051909101600082815581516001805492819052916020601f60026000196101008588161502019093169290920482018190047fb10e2d527612073b26eecdfd717e6a320cf44b4afac2b0732d9fcbe2b7fa0cf69081019392909186019083901060b657805160ff19168380011785555b5060a49291505b8082111560e357600081556001016092565b5050505061014e806100e76000396000f35b82800160010185558215608b579182015b82811115608b57825182600050559160200191906001019060c7565b509056606060405260e060020a60003504636854171d8114610029578063f3acae3a14610037575b610002565b346100025761009b60005481565b34610002576100ad60018054604080516020601f6002600019610100878916150201909516949094049384018190048102820181019092528281529291908301828280156101465780601f1061011b57610100808354040283529160200191610146565b60408051918252519081900360200190f35b60405180806020018281038252838181518152602001915080519060200190808383829060006004602084601f0104600302600f01f150905090810190601f16801561010d5780820380516001836020036101000a031916815260200191505b509250505060405180910390f35b820191906000526020600020905b81548152906001019060200180831161012957829003601f168201915b50505050508156000000000000000000000000000000000000000000000000000000000000007b0000000000000000000000000000000000000000000000000000000000000040000000000000000000000000000000000000000000000000000000000000000d48656c6c6f2c20576f726c6421000000000000000000000000000000000000001ca0e84786ff0c0ed7564a972d3e037ef74d9adada759f845f36246e818f987d2945a038ce5aa5b1a283f3270acd4668e99d410cd7f65ac74f4ae72416b0068935bd51

Sending the Data: part above as the data: parameter in your JSON-RPC eth_sendTransaction transaction will achieve the same action of deploying the contract onto the blockchain with the same constructor arguments.

You can see the first part of the Data: field (not bolded) matching the contract bytecode, and the second part of the Data: field (bolded) represents the constructor arguments.

The constructor arguments are:

// _v1: 0x7b = 123
000000000000000000000000000000000000000000000000000000000000007b
// 0x40 = 64. This is the offset from the beginning of _v1
// directly above to the start of the next set of hex strings
// ending below
0000000000000000000000000000000000000000000000000000000000000040
// 0xd = 13 - the length of the "Hello, World!" string
000000000000000000000000000000000000000000000000000000000000000d
// In geth, 
// > web3.toUtf8("48656c6c6f2c20576f726c642100000000000000000000000000000000000000")
// "Hello, World!"
48656c6c6f2c20576f726c642100000000000000000000000000000000000000

Further references:

Ethereum Contract ABI
How to explain string serialization when invoking contract method?
Can you help me parse this input data from a newProposal transaction from The DAO? for use of the ethabi tool
web3.js - encodeParams, decodeParams, test encodeParams, test decodeParams

Responding to comment below

I've added two more examples to demonstrate the calculation of the offsets.

Example 2

pragma solidity ^0.4.2;

contract Test {
    uint256 public v1;
    uint256 public v2;
    string public v3;

    function Test(uint256 _v1, uint256 _v2, string _v3) {
        v1 = _v1;
        v2 = _v2;
        v3 = _v3;
    }
}

Deployed contract above with the following parameters:

123,456,"thequickbrownfoxjumpsoverthelazydog"

Here is the data to deploy the contract with the constructor, with the parameters bolded:

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

// _v1: 0x7b = 123
000000000000000000000000000000000000000000000000000000000000007b
// _v2: 0x1c8 = 456
00000000000000000000000000000000000000000000000000000000000001c8
// 0x60 = 96. This is the offset from the start of _v1 to the
// start of v3. 32 x 3 = 96
0000000000000000000000000000000000000000000000000000000000000060
// _v3: 0x23 = 35
0000000000000000000000000000000000000000000000000000000000000023
// In geth:
// > web3.toUtf8("746865717569636b62726f776e666f786a756d70736f7665727468656c617a79646f67")
// "thequickbrownfoxjumpsoverthelazydog" (35 chars)
746865717569636b62726f776e666f786a756d70736f7665727468656c617a79
646f670000000000000000000000000000000000000000000000000000000000

Example 3

pragma solidity ^0.4.2;

contract Test {
    uint256 public v1;
    uint256 public v2;
    string public v3;
    string public v4;

    function Test(uint256 _v1, uint256 _v2, string _v3, string _v4) {
        v1 = _v1;
        v2 = _v2;
        v3 = _v3;
        v4 = _v4;
    }
}