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caver.klay.Contract

스마트 컨트랙트와 상호작용하는 데 사용되는 caver-js 객체입니다.
The caver.klay.Contract object makes it easy to interact with smart contracts on the Klaytn blockchain. When you create a new contract object, you give it the JSON interface of the respective smart contract and caver will auto convert all calls into low level ABI calls over RPC for you.
This allows you to interact with smart contracts as if they were JavaScript objects.

new contract

new caver.klay.Contract(jsonInterface [, address] [, options])
Creates a new contract instance with all its methods and events defined in its JSON interface object.
Parameters
Name
Type
Description
jsonInterface
Object
The JSON interface for the contract to instantiate
address
String
(optional) The address of the smart contract to call. Can be added later using myContract.options.address = '0x1234..'
options
Object
(optional) The options of the contract. See the table below for the details.
The options object contains the following:
Name
Type
Description
from
String
(optional) The address from which transactions should be made.
gasPrice
String
(optional) The gas price in peb to use for transactions.
gas
Number
(optional) The maximum gas provided for a transaction (gas limit).
data
String
(optional) The byte code of the contract. Used when the contract gets deployed.
Return Value
Type
Description
Object
The contract instance with all its methods and events.
Example
var myContract = new caver.klay.Contract([...], '0xde0B295669a9FD93d5F28D9Ec85E40f4cb697BAe', {
from: '0x1234567890123456789012345678901234567891', // default from address
gasPrice: '25000000000' // default gas price in peb, 25 Gpeb in this case
});
var myContract = new caver.klay.Contract([...], 'myContract', {
from: '0x1234567890123456789012345678901234567891', // default from address
gasPrice: '25000000000' // default gas price in peb, 25 Gpeb in this case
});

options

myContract.options
The options object for the contract instance. from, gas and gasPrice are used as fallback values when sending transactions.
Properties
Name
Type
Description
address
String
The address where the contract is deployed. Also see options.address.
jsonInterface
Array
The JSON interface of the contract. Also see options.jsonInterface.
data
String
The byte code of the contract. Used when the contract gets deployed.
from
String
트랜잭션이 만들어진 송신자 주소.
gasPrice
String
The gas price in peb to use for transactions.
gas
Number
The maximum gas provided for a transaction (gas limit).
Example
> myContract.options;
{
address: '0x1234567890123456789012345678901234567891',
jsonInterface: [...],
from: '0xde0B295669a9FD93d5F28D9Ec85E40f4cb697BAe',
gasPrice: '10000000000000',
gas: 1000000
}
> myContract.options.from = '0x1234567890123456789012345678901234567891'; // default from address
> myContract.options.gasPrice = '25000000000000'; // default gas price in peb
> myContract.options.gas = 5000000; // provide as fallback always 5M gas

options.address

myContract.options.address
The address used for this contract instance myContract. All transactions generated by caver-js from this contract will contain this address as the "to". 주소는 소문자로 저장됩니다.
Property
Name
Type
Description
address
String \
null
Example
> myContract.options.address;
'0xde0b295669a9fd93d5f28d9ec85e40f4cb697bae'
// set a new address
> myContract.options.address = '0x1234FFDD...';

options.jsonInterface

myContract.options.jsonInterface
The JSON interface object derived from the ABI of this contract myContract.
Property
Name
Type
Description
jsonInterface
Array
The JSON interface for this contract. Re-setting this will regenerate the methods and events of the contract instance.
Example
> myContract.options.jsonInterface;
[{
"type":"function",
"name":"foo",
"inputs": [{"name":"a","type":"uint256"}],
"outputs": [{"name":"b","type":"address"}]
},{
"type":"event",
"name":"Event"
"inputs": [{"name":"a","type":"uint256","indexed":true},{"name":"b","type":"bytes32","indexed":false}],
}]
// set a new interface
> myContract.options.jsonInterface = [...];

clone

myContract.clone()
Clones the current contract instance.
Parameters
None
Return Value
Type
Description
Object
The new cloned contract instance.
Example
> var contract1 = new caver.klay.Contract(abi, address, {gasPrice: '12345678', from: fromAddress});
> var contract2 = contract1.clone();
> contract2.options.address = address2;
> (contract1.options.address !== contract2.options.address);
true

deploy

myContract.deploy(options)
컨트랙트를 Klaytn 블록체인에 배포합니다. After successful deployment, the promise will be resolved with a new contract instance.
Parameters
options: 배포에 사용되는 옵션 객체:
Name
Type
Description
data
String
The byte code of the contract.
arguments
Array
(optional) The arguments that get passed to the constructor on deployment.
Return Value
Object: 트랜잭션 객체:
Type
Description
Array
arguments: 이전에 메소드에 전달되었던 인자. 이들은 변경될 수 있습니다.
Function
send: Will deploy the contract. 프로미스는 영수증 대신 새 컨트랙트 인스턴스를 반환할 것입니다.
Function
estimateGas: Will estimate the gas used for the deployment.
Function
encodeABI: Encodes the ABI of the deployment, which is contract data + constructor parameters.
Example
> myContract.deploy({
data: '0x12345...',
arguments: [123, 'My String']
})
.send({
from: '0x1234567890123456789012345678901234567891',
gas: 1500000,
value: 0,
}, function(error, transactionHash) { ... })
.on('error', function(error) { ... })
.on('transactionHash', function(transactionHash) { ... })
.on('receipt', function(receipt) {
console.log(receipt.contractAddress) // contains the new contract address
})
.then(function(newContractInstance) {
console.log(newContractInstance.options.address) // instance with the new contract address
});
// When the data is already set as an option to the contract itself
> myContract.options.data = '0x12345...';
> myContract.deploy({
arguments: [123, 'My String']
})
.send({
from: '0x1234567890123456789012345678901234567891',
gas: 1500000,
value: 0,
})
.then(function(newContractInstance) {
console.log(newContractInstance.options.address) // instance with the new contract address
});
// Simply encoding
> myContract.deploy({
data: '0x12345...',
arguments: [123, 'My String']
})
.encodeABI();
'0x12345...0000012345678765432'
// Gas estimation
> myContract.deploy({
data: '0x12345...',
arguments: [123, 'My String']
})
.estimateGas(function(err, gas) {
console.log(gas);
});

methods

myContract.methods.myMethod([param1 [, param2 [, ...]]])
Creates a transaction object for that method, which then can be called, sent, estimated or ABI encoded.
이 스마트 컨트랙트의 메소드는 다음을 통해 이용할 수 있습니다:
  • 이름: myContract.methods.myMethod(123)
  • 매개변수가 있는 이름: myContract.methods['myMethod(uint256)'](123)
  • The signature*: myContract.methods['0x58cf5f10'](123)
This allows calling functions with the same name but different parameters from the JavaScript contract object.

cf) *Function signature (Function selector)

The first four bytes of the call data for a function call specifies the function to be called. It is the first (left, high-order in big-endian) four bytes of the Keccak-256 (SHA-3) hash of the signature of the function.
The function signature can be made by 2 different methods. 1. caver.klay.abi.encodeFunctionSignature('funcName(paramType1,paramType2,...)') 2. caver.utils.sha3('funcName(paramType1,paramType2,...)').substr(0, 10)
ex)
caver.klay.abi.encodeFunctionSignature('myMethod(uint256)')
> 0x58cf5f10
caver.utils.sha3('myMethod(uint256)').substr(0, 10)
> 0x58cf5f10
Parameters
모든 메소드의 매개변수는 JSON 인터페이스에 정의된 스마트 컨트랙트 메소드에 의존합니다.
Return Value
Object: The transaction object:
Type
Description
Array
arguments: The arguments passed to the method before. They can be changed.
Function
call: Will call the "constant" method and execute its smart contract method in the Klaytn Virtual Machine without sending a transaction (cannot alter the smart contract state).
Function
send: Will send a transaction to the smart contract and execute its method (can alter the smart contract state).
Function
estimateGas: Will estimate the gas used when the method would be executed on the blockchain.
Function
encodeABI: Encodes the ABI for this method. 트랜잭션을 사용하여 메소드를 호출하거나 인수로써 다른 스마트 컨트랙트 메소드에 전달될 수 있습니다.
Example
// calling a method
> myContract.methods.myMethod(123).call({from: '0xde0B295669a9FD93d5F28D9Ec85E40f4cb697BAe'}, function(error, result) {
...
});
// or sending and using a promise
> myContract.methods.myMethod(123).send({from: '0xde0B295669a9FD93d5F28D9Ec85E40f4cb697BAe'})
.then(function(receipt) {
// receipt can also be a new contract instance, when coming from a "contract.deploy({...}).send()"
});
// or sending and using the events
> myContract.methods.myMethod(123).send({from: '0xde0B295669a9FD93d5F28D9Ec85E40f4cb697BAe'})
.on('transactionHash', function(hash) {
...
})
.on('receipt', function(receipt) {
...
})
.on('error', console.error);

methods.myMethod.call

myContract.methods.myMethod([param1 [, param2 [, ...]]]).call(options [, callback])
Will call a "constant" method and execute its smart contract method in the Klaytn Virtual Machine without sending any transaction. Note that calling cannot alter the smart contract state.
Parameters
Name
Type
Description
options
Object
(optional) The options used for calling. See the table below for the details.
callback
Function
(optional) This callback will be fired with the result of the smart contract method execution as the second argument, or with an error object as the first argument.
The options object can contain the following:
Name
Type
Description
from
String
(optional) The address the call “transaction” should be made from.
gasPrice
String
(optional) The gas price in peb to use for this call "transaction".
gas
Number
(optional) The maximum gas provided for this call "transaction" (gas limit).
Return Value
Promise returns Mixed: The return value(s) of the smart contract method. If it returns a single value, it is returned as it is. If it has multiple return values, they are returned as an object with properties and indices.
Example
// using the callback
> myContract.methods.myMethod(123).call({from: '0xde0B295669a9FD93d5F28D9Ec85E40f4cb697BAe'}, function(error, result) {
...
});
// using the promise
> myContract.methods.myMethod(123).call({from: '0xde0B295669a9FD93d5F28D9Ec85E40f4cb697BAe'})
.then(function(result) {
...
});
// Solidity: MULTI-ARGUMENT RETURN
contract MyContract {
function myFunction() returns(uint256 myNumber, string myString) {
return (23456, "Hello!%");
}
}
> var MyContract = new caver.klay.Contract(abi, address);
> MyContract.methods.myFunction().call().then(console.log);
Result {
myNumber: '23456',
myString: 'Hello!%',
0: '23456', // these are here as fallbacks if the name is not known or given
1: 'Hello!%'
}
// Solidity: SINGLE-ARGUMENT RETURN
contract MyContract {
function myFunction() returns(string myString) {
return "Hello!%";
}
}
> var MyContract = new caver.klay.Contract(abi, address);
> MyContract.methods.myFunction().call().then(console.log);
"Hello!%"

methods.myMethod.send

myContract.methods.myMethod([param1 [, param2 [, ...]]]).send(options [, callback])
스마트 컨트랙트에 트랜잭션을 보내고 그 메소드를 실행합니다. Note that this can alter the smart contract state.
Parameters
Name
Type
Description
options
Object
The options used for sending. See the table below for the details.
callback
Function
(optional) This callback will be fired first with the "transactionHash", or with an error object as the first argument.
The options object can contain the following:
Name
Type
Description
from
String
The address from which the transaction should be sent.
gasPrice
String
(optional) The gas price in peb to use for this transaction.
gas
Number
The maximum gas provided for this transaction (gas limit).
value
Number \
String | BN | BigNumber
Return Value
callback은 32바이트 트랜잭션 해시를 반환합니다.
PromiEvent: 프로미스(promise)가 조합된 이벤트 이미터(event emitter). Will be resolved when the transaction receipt is available, or if this send() is called from a someContract.deploy(), then the promise will be resolved with the new contract instance. 추가로 다음과 같은 이벤트를 사용할 수 있습니다:
Name
Type
Description
transactionHash
String
트랜잭션이 전송된 직후 및 트랜잭션 해시를 사용할 수 있을 때 발생합니다.
receipt
Object
트랜잭션 영수증을 사용할 수 있을 때 발생합니다. 컨트랙트의 영수증에는 logs 속성이 없지만, 대신 이벤트 이름을 키로, 이벤트를 속성으로 하는 events 속성이 있습니다. See getPastEvents return values for details about the returned event object.
error
Error
전송 중 오류가 발생하면 발생됩니다. On an out-of-gas error, the second parameter is the receipt.
Example
// using the callback
> myContract.methods.myMethod(123).send({from: '0xde0B295669a9FD93d5F28D9Ec85E40f4cb697BAe'}, function(error, transactionHash) {
...
});
// using the promise
> myContract.methods.myMethod(123).send({from: '0xde0B295669a9FD93d5F28D9Ec85E40f4cb697BAe'})
.then(function(receipt) {
// receipt can also be a new contract instance, when coming from a "contract.deploy({...}).send()"
});
// using the event emitter
> myContract.methods.myMethod(123).send({from: '0xde0B295669a9FD93d5F28D9Ec85E40f4cb697BAe'})
.on('transactionHash', function(hash) {
...
})
.on('receipt', function(receipt) {
console.log(receipt);
})
.on('error', console.error); // If there is an out-of-gas error, the second parameter is the receipt.
// receipt example
{
"transactionHash": "0x9fc76417374aa880d4449a1f7f31ec597f00b1f6f3dd2d66f4c9c6c445836d8b",
"transactionIndex": 0,
"blockHash": "0xef95f2f1ed3ca60b048b4bf67cde2195961e0bba6f70bcbea9a2c4e133e34b46",
"blockNumber": 3,
"contractAddress": "0x11f4d0A3c12e86B4b5F39B213F7E19D048276DAe",
"gasUsed": 30234,
"events": {
"MyEvent": {
returnValues: {
myIndexedParam: 20,
myOtherIndexedParam: '0x123456789...',
myNonIndexParam: 'My String'
},
raw: {
data: '0x7f9fade1c0d57a7af66ab4ead79fade1c0d57a7af66ab4ead7c2c2eb7b11a91385',
topics: ['0xfd43ade1c09fade1c0d57a7af66ab4ead7c2c2eb7b11a91ffdd57a7af66ab4ead7', '0x7f9fade1c0d57a7af66ab4ead79fade1c0d57a7af66ab4ead7c2c2eb7b11a91385']
},
event: 'MyEvent',
signature: '0xfd43ade1c09fade1c0d57a7af66ab4ead7c2c2eb7b11a91ffdd57a7af66ab4ead7',
logIndex: 0,
transactionIndex: 0,
transactionHash: '0x7f9fade1c0d57a7af66ab4ead79fade1c0d57a7af66ab4ead7c2c2eb7b11a91385',
blockHash: '0xfd43ade1c09fade1c0d57a7af66ab4ead7c2c2eb7b11a91ffdd57a7af66ab4ead7',
blockNumber: 1234,
address: '0xde0B295669a9FD93d5F28D9Ec85E40f4cb697BAe'
},
"MyOtherEvent": {
...
},
"MyMultipleEvent":[{...}, {...}] // If there are a multiple of the same events, they will be in an array.
}
}

methods.myMethod.estimateGas

myContract.methods.myMethod([param1 [, param2 [, ...]]]).estimateGas(options [, callback])
Will estimate the gas that a method execution will take when executed in the Klaytn Virtual Machine. The estimation can differ from the actual gas used when later sending a transaction, as the state of the smart contract can be different at that time.
Parameters
Name
Type
Description
options
Object
(optional) The options used for calling. See the table below for the details.
callback
Function
(optional) This callback will be fired with the result of the gas estimation as the second argument, or with an error object as the first argument.
The options object can contain the following:
Name
Type
Description
from
String
(optional) The address from which the call "transaction" should be made.
gas
Number
(optional) The maximum gas provided for this call "transaction" (gas limit). Setting a specific value helps to detect out of gas errors. If all gas is used, it will return the same number.
value
Number \
String | BN | BigNumber
Return Value
PromiseNumber를 반환합니다 - 모의 호출/트랜잭션에 사용된 가스.
Example
// using the callback
> myContract.methods.myMethod(123).estimateGas({gas: 5000000}, function(error, gasAmount) {
if(gasAmount == 5000000)
console.log('Method ran out of gas');
});
// using the promise
> myContract.methods.myMethod(123).estimateGas({from: '0xde0B295669a9FD93d5F28D9Ec85E40f4cb697BAe'})
.then(function(gasAmount) {
...
})
.catch(function(error) {
...
});

methods.myMethod.encodeABI

myContract.methods.myMethod([param1 [, param2[, ...]]]).encodeABI()
Encodes the ABI for this method. This can be used to send a transaction, call a method, or pass it into another smart contract method as arguments.
Parameters
None
Return Value
Type
Description
String
The encoded ABI byte code to send via a transaction or call.
Example
> myContract.methods.myMethod(123).encodeABI();
'0x58cf5f1000000000000000000000000000000000000000000000000000000000000007B'

once

myContract.once(event [, options], callback)
Subscribes to an event and unsubscribes immediately after the first event or error. Will only fire for a single event.
Parameters
Name
Type
Description
event
String
컨트랙트, 또는 모든 이벤트를 받기 위한 "allEvents"에서의 이벤트 이름.
options
Object
(optional) The options used for deployment. See the table below for the details.
callback
Function
This callback will be fired for the first event as the second argument, or an error as the first argument. See getPastEvents return values for details about the event structure.
The options object can contain the following:
Name
Type
Description
filter
Object
(optional) Lets you filter events by indexed parameters, e.g., {filter: {myNumber: [12,13]}} means all events where "myNumber" is 12 or 13.
topics
Array
(optional) This allows you to manually set the topics for the event filter. 필터 특성 및 이벤트 서명이 제공되면, topic[0] 가 자동으로 설정되지 않습니다.
Return Value
undefined
Example
> myContract.once('MyEvent', {
filter: {myIndexedParam: [20,23], myOtherIndexedParam: '0x123456789...'}, // Using an array means OR: e.g. 20 or 23
}, function(error, event) { console.log(event); });
// event output example
{
returnValues: {
myIndexedParam: 20,
myOtherIndexedParam: '0x123456789...',
myNonIndexParam: 'My String'
},
raw: {
data: '0x7f9fade1c0d57a7af66ab4ead79fade1c0d57a7af66ab4ead7c2c2eb7b11a91385',
topics: ['0xfd43ade1c09fade1c0d57a7af66ab4ead7c2c2eb7b11a91ffdd57a7af66ab4ead7', '0x7f9fade1c0d57a7af66ab4ead79fade1c0d57a7af66ab4ead7c2c2eb7b11a91385']
},
event: 'MyEvent',
signature: '0xfd43ade1c09fade1c0d57a7af66ab4ead7c2c2eb7b11a91ffdd57a7af66ab4ead7',
logIndex: 0,
transactionIndex: 0,
transactionHash: '0x7f9fade1c0d57a7af66ab4ead79fade1c0d57a7af66ab4ead7c2c2eb7b11a91385',
blockHash: '0xfd43ade1c09fade1c0d57a7af66ab4ead7c2c2eb7b11a91ffdd57a7af66ab4ead7',
blockNumber: 1234,
address: '0xde0B295669a9FD93d5F28D9Ec85E40f4cb697BAe'
}

events

myContract.events.MyEvent([options][, callback])
이벤트를 구독합니다.
Parameters
Name
Type
Description
options
Object
(optional) The options used for deployment. See the table below for the details.
callback
Function
(optional) This callback will be fired for each event as the second argument, or an error as the first argument.
The options object can contain the following:
Name
Type
Description
filter
Object
(optional) Lets you filter events by indexed parameters, e.g., {filter: {myNumber: [12,13]}} means all events where "myNumber" is 12 or 13.
fromBlock
Number
(optional) The block number from which to get events on.
topics
Array
(optional) This allows to manually set the topics for the event filter. If given the filter property and event signature, topic[0] will not be set automatically.
Return Value
EventEmitter: 이벤트 이미터는 다음 이벤트를 가집니다:
Name
Type
Description
data
Object
이벤트 객체를 인수로 각 수신 이벤트를 발생합니다.
error
Object
구독 오류가 발생하면 발생합니다.
반환된 이벤트 Object의 구조는 다음과 같습니다:
Name
Type
Description
event
String
이벤트 이름.
signature
String \
null
address
String
이 이벤트가 발생한 주소.
returnValues
Object
The return values coming from the event, e.g., {myVar: 1, myVar2: '0x234...'}.
logIndex
Number
블록에서 이벤트 인덱스 위치의 정수값.
transactionIndex
Number
이벤트가 생성된 트랜잭션의 인덱스 위치의 정수값.
transactionHash
32-byte String