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title actions requireLogin material
Komunikácia s Kontraktmi
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index.html cryptozombies_abi.js zombieownership.sol zombieattack.sol zombiehelper.sol zombiefeeding.sol zombiefactory.sol ownable.sol safemath.sol erc721.sol
<!DOCTYPE html> <html lang="en"> <head> <meta charset="UTF-8"> <title>CryptoZombies front-end</title> <script language="javascript" type="text/javascript" src="https://cdnjs.cloudflare.com/ajax/libs/jquery/3.3.1/jquery.min.js"></script> <script language="javascript" type="text/javascript" src="web3.min.js"></script> <!-- 1. Include cryptozombies_abi.js here --> </head> <body> <script> // 2. Tu začni písať kód window.addEventListener('load', function() { // Skontrolujeme či bol Web3 vložený do našeho prehliadača (Mist/Metamask) if (typeof web3 !== 'undefined') { // Použi provider Mistu/MetaMasku web3js = new Web3(web3.currentProvider); } else { // Musíme sa postarať o prípad kedy užívateľ nemá v prehliadači web3. // Zrejme im ukážeme správu, že si musia nainštalovať Metamask // na to, aby našu aplikáciu mohli používať } // Teraz môžme naštartovať našu aplikáciu a používať web3js startApp() }) </script> </body> </html>
var cryptoZombiesABI = [ { "constant": false, "inputs": [ { "name": "_to", "type": "address" }, { "name": "_tokenId", "type": "uint256" } ], "name": "approve", "outputs": [], "payable": false, "stateMutability": "nonpayable", "type": "function" }, { "constant": false, "inputs": [ { "name": "_zombieId", "type": "uint256" } ], "name": "levelUp", "outputs": [], "payable": true, "stateMutability": "payable", "type": "function" }, { "constant": false, "inputs": [ { "name": "_zombieId", "type": "uint256" }, { "name": "_kittyId", "type": "uint256" } ], "name": "feedOnKitty", "outputs": [], "payable": false, "stateMutability": "nonpayable", "type": "function" }, { "constant": true, "inputs": [ { "name": "", "type": "uint256" } ], "name": "zombies", "outputs": [ { "name": "name", "type": "string" }, { "name": "dna", "type": "uint256" }, { "name": "level", "type": "uint32" }, { "name": "readyTime", "type": "uint32" }, { "name": "winCount", "type": "uint16" }, { "name": "lossCount", "type": "uint16" } ], "payable": false, "stateMutability": "view", "type": "function" }, { "constant": false, "inputs": [], "name": "withdraw", "outputs": [], "payable": false, "stateMutability": "nonpayable", "type": "function" }, { "constant": true, "inputs": [ { "name": "_owner", "type": "address" } ], "name": "getZombiesByOwner", "outputs": [ { "name": "", "type": "uint256[]" } ], "payable": false, "stateMutability": "view", "type": "function" }, { "constant": true, "inputs": [ { "name": "", "type": "uint256" } ], "name": "zombieToOwner", "outputs": [ { "name": "", "type": "address" } ], "payable": false, "stateMutability": "view", "type": "function" }, { "constant": false, "inputs": [ { "name": "_address", "type": "address" } ], "name": "setKittyContractAddress", "outputs": [], "payable": false, "stateMutability": "nonpayable", "type": "function" }, { "constant": false, "inputs": [ { "name": "_zombieId", "type": "uint256" }, { "name": "_newDna", "type": "uint256" } ], "name": "changeDna", "outputs": [], "payable": false, "stateMutability": "nonpayable", "type": "function" }, { "constant": true, "inputs": [ { "name": "_tokenId", "type": "uint256" } ], "name": "ownerOf", "outputs": [ { "name": "_owner", "type": "address" } ], "payable": false, "stateMutability": "view", "type": "function" }, { "constant": true, "inputs": [ { "name": "_owner", "type": "address" } ], "name": "balanceOf", "outputs": [ { "name": "_balance", "type": "uint256" } ], "payable": false, "stateMutability": "view", "type": "function" }, { "constant": false, "inputs": [ { "name": "_name", "type": "string" } ], "name": "createRandomZombie", "outputs": [], "payable": false, "stateMutability": "nonpayable", "type": "function" }, { "constant": true, "inputs": [], "name": "owner", "outputs": [ { "name": "", "type": "address" } ], "payable": false, "stateMutability": "view", "type": "function" }, { "constant": false, "inputs": [ { "name": "_to", "type": "address" }, { "name": "_tokenId", "type": "uint256" } ], "name": "transfer", "outputs": [], "payable": false, "stateMutability": "nonpayable", "type": "function" }, { "constant": true, "inputs": [], "name": "getAllZombies", "outputs": [ { "name": "", "type": "uint256[]" } ], "payable": false, "stateMutability": "view", "type": "function" }, { "constant": false, "inputs": [ { "name": "_tokenId", "type": "uint256" } ], "name": "takeOwnership", "outputs": [], "payable": false, "stateMutability": "nonpayable", "type": "function" }, { "constant": false, "inputs": [ { "name": "_zombieId", "type": "uint256" }, { "name": "_newName", "type": "string" } ], "name": "changeName", "outputs": [], "payable": false, "stateMutability": "nonpayable", "type": "function" }, { "constant": false, "inputs": [ { "name": "_fee", "type": "uint256" } ], "name": "setLevelUpFee", "outputs": [], "payable": false, "stateMutability": "nonpayable", "type": "function" }, { "constant": false, "inputs": [ { "name": "_zombieId", "type": "uint256" }, { "name": "_targetId", "type": "uint256" } ], "name": "attack", "outputs": [], "payable": false, "stateMutability": "nonpayable", "type": "function" }, { "constant": false, "inputs": [ { "name": "newOwner", "type": "address" } ], "name": "transferOwnership", "outputs": [], "payable": false, "stateMutability": "nonpayable", "type": "function" }, { "anonymous": false, "inputs": [ { "indexed": true, "name": "_from", "type": "address" }, { "indexed": true, "name": "_to", "type": "address" }, { "indexed": false, "name": "_tokenId", "type": "uint256" } ], "name": "Transfer", "type": "event" }, { "anonymous": false, "inputs": [ { "indexed": true, "name": "_owner", "type": "address" }, { "indexed": true, "name": "_approved", "type": "address" }, { "indexed": false, "name": "_tokenId", "type": "uint256" } ], "name": "Approval", "type": "event" }, { "anonymous": false, "inputs": [ { "indexed": false, "name": "attackResult", "type": "bool" }, { "indexed": false, "name": "winCount", "type": "uint16" }, { "indexed": false, "name": "lossCount", "type": "uint16" } ], "name": "AttackResult", "type": "event" }, { "anonymous": false, "inputs": [ { "indexed": false, "name": "zombieId", "type": "uint256" }, { "indexed": false, "name": "name", "type": "string" }, { "indexed": false, "name": "dna", "type": "uint256" } ], "name": "NewZombie", "type": "event" }, { "anonymous": false, "inputs": [ { "indexed": true, "name": "previousOwner", "type": "address" }, { "indexed": true, "name": "newOwner", "type": "address" } ], "name": "OwnershipTransferred", "type": "event" } ]
pragma solidity ^0.4.19; import "./zombieattack.sol"; import "./erc721.sol"; import "./safemath.sol"; contract ZombieOwnership is ZombieAttack, ERC721 { using SafeMath for uint256; mapping (uint => address) zombieApprovals; function balanceOf(address _owner) public view returns (uint256 _balance) { return ownerZombieCount[_owner]; } function ownerOf(uint256 _tokenId) public view returns (address _owner) { return zombieToOwner[_tokenId]; } function _transfer(address _from, address _to, uint256 _tokenId) private { ownerZombieCount[_to] = ownerZombieCount[_to].add(1); ownerZombieCount[msg.sender] = ownerZombieCount[msg.sender].sub(1); zombieToOwner[_tokenId] = _to; Transfer(_from, _to, _tokenId); } function transfer(address _to, uint256 _tokenId) public onlyOwnerOf(_tokenId) { _transfer(msg.sender, _to, _tokenId); } function approve(address _to, uint256 _tokenId) public onlyOwnerOf(_tokenId) { zombieApprovals[_tokenId] = _to; Approval(msg.sender, _to, _tokenId); } function takeOwnership(uint256 _tokenId) public { require(zombieApprovals[_tokenId] == msg.sender); address owner = ownerOf(_tokenId); _transfer(owner, msg.sender, _tokenId); } }
pragma solidity ^0.4.19; import "./zombiehelper.sol"; contract ZombieAttack is ZombieHelper { uint randNonce = 0; uint attackVictoryProbability = 70; function randMod(uint _modulus) internal returns(uint) { randNonce++; return uint(keccak256(now, msg.sender, randNonce)) % _modulus; } function attack(uint _zombieId, uint _targetId) external onlyOwnerOf(_zombieId) { Zombie storage myZombie = zombies[_zombieId]; Zombie storage enemyZombie = zombies[_targetId]; uint rand = randMod(100); if (rand <= attackVictoryProbability) { myZombie.winCount++; myZombie.level++; enemyZombie.lossCount++; feedAndMultiply(_zombieId, enemyZombie.dna, "zombie"); } else { myZombie.lossCount++; enemyZombie.winCount++; _triggerCooldown(myZombie); } } }
pragma solidity ^0.4.19; import "./zombiefeeding.sol"; contract ZombieHelper is ZombieFeeding { uint levelUpFee = 0.001 ether; modifier aboveLevel(uint _level, uint _zombieId) { require(zombies[_zombieId].level >= _level); _; } function withdraw() external onlyOwner { owner.transfer(this.balance); } function setLevelUpFee(uint _fee) external onlyOwner { levelUpFee = _fee; } function levelUp(uint _zombieId) external payable { require(msg.value == levelUpFee); zombies[_zombieId].level++; } function changeName(uint _zombieId, string _newName) external aboveLevel(2, _zombieId) onlyOwnerOf(_zombieId) { zombies[_zombieId].name = _newName; } function changeDna(uint _zombieId, uint _newDna) external aboveLevel(20, _zombieId) onlyOwnerOf(_zombieId) { zombies[_zombieId].dna = _newDna; } function getZombiesByOwner(address _owner) external view returns(uint[]) { uint[] memory result = new uint[](ownerZombieCount[_owner]); uint counter = 0; for (uint i = 0; i < zombies.length; i++) { if (zombieToOwner[i] == _owner) { result[counter] = i; counter++; } } return result; } }
pragma solidity ^0.4.19; import "./zombiefactory.sol"; contract KittyInterface { function getKitty(uint256 _id) external view returns ( bool isGestating, bool isReady, uint256 cooldownIndex, uint256 nextActionAt, uint256 siringWithId, uint256 birthTime, uint256 matronId, uint256 sireId, uint256 generation, uint256 genes ); } contract ZombieFeeding is ZombieFactory { KittyInterface kittyContract; modifier onlyOwnerOf(uint _zombieId) { require(msg.sender == zombieToOwner[_zombieId]); _; } function setKittyContractAddress(address _address) external onlyOwner { kittyContract = KittyInterface(_address); } function _triggerCooldown(Zombie storage _zombie) internal { _zombie.readyTime = uint32(now + cooldownTime); } function _isReady(Zombie storage _zombie) internal view returns (bool) { return (_zombie.readyTime <= now); } function feedAndMultiply(uint _zombieId, uint _targetDna, string _species) internal onlyOwnerOf(_zombieId) { Zombie storage myZombie = zombies[_zombieId]; require(_isReady(myZombie)); _targetDna = _targetDna % dnaModulus; uint newDna = (myZombie.dna + _targetDna) / 2; if (keccak256(_species) == keccak256("kitty")) { newDna = newDna - newDna % 100 + 99; } _createZombie("NoName", newDna); _triggerCooldown(myZombie); } function feedOnKitty(uint _zombieId, uint _kittyId) public { uint kittyDna; (,,,,,,,,,kittyDna) = kittyContract.getKitty(_kittyId); feedAndMultiply(_zombieId, kittyDna, "kitty"); } }
pragma solidity ^0.4.19; import "./ownable.sol"; import "./safemath.sol"; contract ZombieFactory is Ownable { using SafeMath for uint256; event NewZombie(uint zombieId, string name, uint dna); uint dnaDigits = 16; uint dnaModulus = 10 ** dnaDigits; uint cooldownTime = 1 days; struct Zombie { string name; uint dna; uint32 level; uint32 readyTime; uint16 winCount; uint16 lossCount; } Zombie[] public zombies; mapping (uint => address) public zombieToOwner; mapping (address => uint) ownerZombieCount; function _createZombie(string _name, uint _dna) internal { uint id = zombies.push(Zombie(_name, _dna, 1, uint32(now + cooldownTime), 0, 0)) - 1; zombieToOwner[id] = msg.sender; ownerZombieCount[msg.sender]++; NewZombie(id, _name, _dna); } function _generateRandomDna(string _str) private view returns (uint) { uint rand = uint(keccak256(_str)); return rand % dnaModulus; } function createRandomZombie(string _name) public { require(ownerZombieCount[msg.sender] == 0); uint randDna = _generateRandomDna(_name); randDna = randDna - randDna % 100; _createZombie(_name, randDna); } }
/** * @title Ownable * @dev The Ownable contract has an owner address, and provides basic authorization control * functions, this simplifies the implementation of "user permissions". */ contract Ownable { address public owner; event OwnershipTransferred(address indexed previousOwner, address indexed newOwner); /** * @dev The Ownable constructor sets the original `owner` of the contract to the sender * account. */ function Ownable() public { owner = msg.sender; } /** * @dev Throws if called by any account other than the owner. */ modifier onlyOwner() { require(msg.sender == owner); _; } /** * @dev Allows the current owner to transfer control of the contract to a newOwner. * @param newOwner The address to transfer ownership to. */ function transferOwnership(address newOwner) public onlyOwner { require(newOwner != address(0)); OwnershipTransferred(owner, newOwner); owner = newOwner; } }
pragma solidity ^0.4.18; /** * @title SafeMath * @dev Math operations with safety checks that throw on error */ library SafeMath { /** * @dev Multiplies two numbers, throws on overflow. */ function mul(uint256 a, uint256 b) internal pure returns (uint256) { if (a == 0) { return 0; } uint256 c = a * b; assert(c / a == b); return c; } /** * @dev Integer division of two numbers, truncating the quotient. */ function div(uint256 a, uint256 b) internal pure returns (uint256) { // assert(b > 0); // Solidity automatically throws when dividing by 0 uint256 c = a / b; // assert(a == b * c + a % b); // There is no case in which this doesn't hold return c; } /** * @dev Subtracts two numbers, throws on overflow (i.e. if subtrahend is greater than minuend). */ function sub(uint256 a, uint256 b) internal pure returns (uint256) { assert(b <= a); return a - b; } /** * @dev Adds two numbers, throws on overflow. */ function add(uint256 a, uint256 b) internal pure returns (uint256) { uint256 c = a + b; assert(c >= a); return c; } }
contract ERC721 { event Transfer(address indexed _from, address indexed _to, uint256 _tokenId); event Approval(address indexed _owner, address indexed _approved, uint256 _tokenId); function balanceOf(address _owner) public view returns (uint256 _balance); function ownerOf(uint256 _tokenId) public view returns (address _owner); function transfer(address _to, uint256 _tokenId) public; function approve(address _to, uint256 _tokenId) public; function takeOwnership(uint256 _tokenId) public; }
<!DOCTYPE html> <html lang="en"> <head> <meta charset="UTF-8"> <title>CryptoZombies front-end</title> <script language="javascript" type="text/javascript" src="https://cdnjs.cloudflare.com/ajax/libs/jquery/3.3.1/jquery.min.js"></script> <script language="javascript" type="text/javascript" src="web3.min.js"></script> <script language="javascript" type="text/javascript" src="cryptozombies_abi.js"></script> </head> <body> <script> var cryptoZombies; function startApp() { var cryptoZombiesAddress = "YOUR_CONTRACT_ADDRESS"; cryptoZombies = new web3js.eth.Contract(cryptoZombiesABI, cryptoZombiesAddress); } window.addEventListener('load', function() { // Checking if Web3 has been injected by the browser (Mist/MetaMask) if (typeof web3 !== 'undefined') { // Use Mist/MetaMask's provider web3js = new Web3(web3.currentProvider); } else { // Handle the case where the user doesn't have Metamask installed // Probably show them a message prompting them to install Metamask } // Now you can start your app & access web3 freely: startApp() }) </script> </body> </html>

Teraz keď už máme pripravné Web3.js pre použitie s Web3 providerom z Metamasku, môžeme ho nastaviť aby komunikoval s našim kontraktom.

Web3.js potrebuje 2 veci na to, aby mohol s našim kontraktom komunikovať. Jeho adresu a ABI.

Adresa kontraktu

Po tom čo dokončíme prácu našom smart kontrakte, budeme ho musieť skompilovať a nasadiť na Ethéreum. Ako kontrakt nasadiť pokryjeme v ďalšej lekcii. Nakoľko nasadzovanie je niečo ako klasické písanie kódu, rozhodli sme sa že trochu zamiešame poradie, a preto práve v tejto lekcii najprv pokrývame Web3.js.

Po tom čo nasadíš svoj kontrakt, dostaneš jeho adresu na Ethereum blockchaine, na ktorej zostane už navždy k dispozícii. Ak si spomínaš z Lekcie 2, adresa CryptoKitties kontraktu na hlavnej sieti Ethereum je YOUR_CONTRACT_ADDRESS.

Po tom čo nasadíš svoj smart kontrakt, budeš si potrebovať skopírovať jeho adresu na to, aby si ním tvoja webová aplikácia mohla pracovať.

ABI Kontraktu

Ďalšia vec, ktorú Web3.js bude potrebovať na to aby mohol s tvojim kontraktom pracovať je jeho ABI.

ABI je skratka pre Application Binary Interface (Binárne Rozhranie Aplikácie). V podstate je to reprezentácia metód tvojho kontraktu v JSON formáte. Tá Web3.js hovorí, ako s tvojím kontraktom na blockchain pracovať.

Keď kontrakt skompiluješ a nasadíš ho na Ethereum (na to sa pozrieme v Lekcií 7), Solidity kompilátor ti vráti jeho ABI. To si musíš skopírovať a uložiť, podobne ako adresu nasadeného kontraktu.

Keďže sme zatiaľ kompilovanie a nasadzovanie nepokryli, v tejto lekcii sme pre teba smart kontrakt skompilovali, a výsledné ABI sme uložili do premennej cryptoZombiesABI v súbore cryptozombies_abi.js.

Ak includujeme do našeho projektu cryptozombies_abi.js, budeme cez túto premennú schopný pristúpiť ku CryptoZombies ABI.

Vytváranie inštancie Web3.js kontraktu

Teraz keď máme ABI kontraktu a jeho Ethéreum adresu po nasadení, môžeme v javascripte vytvoriť jeho Web3 inštanciu takto:

// Vytvorme inštanciu kontraktu myContract
var myContract = new web3js.eth.Contract(myABI, myContractAddress);

Vyskúšaj si to sám

  1. V <head> našeho dokumentu naincluduj pomocou <script> tagu súbor cryptozombies_abi.js, aby sme mohli používať ABI definíciu v našom projekte.

  2. Na začiatku <script> tagu vo vnútri <body> deklaruj premennú var cryptoZombies. Zatiaľ jej hodnotu ale nenastavuj. Neskôr túto premennú použijeme pre uloženie inštancie našeho kontraktu.

  3. Ďalej vytvor funkciu function startApp(). Jej telo vyplníme v nasledujúcich dvoch krokoch.

  4. Prvá vec, ktorú by startApp() mala spraviť je deklarovať premennú var cryptoZombiesAddress a nastaviť jej hodnotu na "YOUR_CONTRACT_ADDRESS" (to je adresa CryptoZombies kontraktu na hlavnej Ethereum sieti, tzv. Ethereum MainNet).

  5. Na záver vytvoríme inštanciu našeho kontraktu. Hodnotu cryptoZombies priraď referenciu na novú inštanciu web3js.eth.Contract. Presne tak, ako sme to urobili v ukážkovom kóde vyššie (ako parametre použi cryptoZombiesABI, ku ktorému si dostal prístup importovanim prostredníctvo script tagu. Ao druhý použi parameter premennú cryptoZombiesAddress).