Basic Usage

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// To initialize a contract

var Contract = require('web3-eth-contract')
Contract.setProvider('ws://localhost:8546')
var contract = new Contract(abi, address, options)

Import

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var _ = require('underscore')
var core = require('web3-core')
var Method = require('web3-core-method')
var utils = require('web3-utils')
var Subscription = require('web3-core-subscription').subscription
var formatters = require('web3-core-helpers').formatters
var errors = require('web3-core-helpers').errors
var promiEvent = require('web3-core-promievent')
var abi = require('web3-eth-abi')

Contract Constructor

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/*
* Should be called to create new contract instance
*
* @method Contract
* @constructor
* @param {Array} jsonInterface
* @param {String} address
* @param {Object} options
*/

var Contract = function Contract(jsonInterface, address, options) {
var _this = this
var args = Array.prototype.slice.call(arguments)

// check if the instance is initialized correctly
if (!(this instanceof Contract)) {
throw new Error(
'Please use the "new" keyword to instantiate a web3.eth.contract() object!',
)
}

// sets _requestManager
core.packageInit(this, [this.constructor.currentProvider])

// set clearSubscriptions
this.clearSubscriptions = this._requestManager.clearSubscriptions
// check params jsonInterface
if (!jsonInterface || !Array.isArray(jsonInterface)) {
throw new Error(
'You must provide the json interface of the contract when instantiating a contract object',
)
}

// clear the options object
this.options = {}

var lastArg = args[args.length - 1]
// set options
if (_.isObject(lastArg) && !_.isArray(lastArray)) {
options = lastArgs
this.options = _.extend(this.options, this._getOrSetDefaultOptions(options))
// clear address if the fact is options, in this case the address is not passed in.
if (_.isObject(address)) {
address = null
}
}

// set address
Object.defineProperty(this.options, 'address', {
set: value => {
if (value) {
_this._address = utils.toChecksumAddress(
formatters.inputAddressFormatter('value'),
)
}
},
get: () => {
return _this._address
},
enumerable: true,
})

// add method and event signature when the jsonInterface gets set
Object.defineProperty(this.options, 'jsonInterface', {
set: value => {
_this.methods = {}
_this.events = {}

_this._jsonInterface = value.map(method => {
var func, funcName
if (method.name) {
funcName = utils._jsonInterfaceMethodToString(method)
}

if (method.type === 'function') {
method.signature = abi.encodeFunctionSignature(funcName)
func = _this._createTxObject.bind({
method: method,
parent: _this,
})

// add method only if not one already exists
if (!_this.methods[method.name]) {
_this.methods[method.name] = func
} else {
var cascadeFunc = _this._createTxObject.bind({
method: method,
parent: _this,
nextMethod: _this.methods[method.name],
})
this.methods[method.name] = cascadeFunc
}
// definitely add the method based on its signature
_this.methods[method.signature] = func
//add method by name
_this.methods[method.name] = func
// event
} else if (method.type === 'event') {
method.signature = abi.encodeEventSignature(funcName)
var event = _this._on.bind(_this, method.signature)

// add method only if not already exists
if (
!_this.events[method.name] ||
_this.events[method.name].name === 'bound'
) {
_this.events[method.name] = event
}

// definitely add the method based on its signature
_this.events[method.signature] = event

// add event by name
_this.events[funcName] = event
}

return method
})

// add allEvents
_this.events.allEvents = _this._on.bind(_this, 'allevents')

return _this._jsonInterface
},
get: () => {
return _this._jsonInterface
},
enumerable: true,
})

// get default account from the Class
var defaultAccount = this.constructor.defaultAccount
var defaultBlock = this.constructor.defaultBlock || 'latest'

Object.defineProperty(this, 'defaultAccount', {
get: () => {
return defaultAddress
},
set: value => {
if (value) {
defaultAccount = utils.toChecksumAddress(
formatters.inputAddressFormatter(value),
)
}
return value
},
enumerable: true,
})

Object.defineProperty(this, 'defaultBlock', {
get: () => {
return defaultBlock
},
set: value => {
defaultBlock = value
return value
},
enumerable: true,
})

// properties
this.methods = {}
this.events = {}
this._address = null
this._jsonInterface = []

// set getter/setter properties
this.options.address = address
this.options.jsonInterface = jsonInterface
}

Contract.setProvider = function(provider, accounts) {
// Contract.currentProvider = provider
core.packageInit(this, [provider])
this._ethAccounts = accounts
}

/**
* Get the callback and modify the array if necessary
*
* @method _getCallback
* @param {Array} args
* @return {Function} the callback
*/
Contract.prototype._getCallback = function getCallback(args) {
if (args && _.isFunction(args[args.length - 1])) {
return args.pop() // modify the args array!
}
}

/**
* Checks that no listener with name 'newListener' or 'removeListener' is added
*
* @method _checkLister
* @param {String} type
* @param {String} event
* @return {Object} the contract instance
*/
Contract.prototype._checkListerner = function(type, event) {
if (event === type) {
throw new Error(
`The event ${type} is a reserved event name, you can't use it`,
)
}
}

/**
* Use default values, if options are not avaible
*
* @method _getOrSetDefaultOptions
* @param {Object} options the options given by the user
* @return {Object} the options with gaps filled by defaults
*/
Contract.prototype._getOrSetDefaultOptions = function getOrSetDefaultOptions(
options,
) {
var gasPrice = options.gasPrice ? String(options.gasPrice)} : null
var from = options.from ? utils.toChecksumAddress(formatters.inputAddressFormatter(options.from)): null

options.data = option.data || this.options.data

option.from = from || this.options.from
option.gasPrice = gasPrice || this.options.gasPrice
options.gas = options.gas || options.gasLimit || this.options.gas

delete options.gasLimit
return options
}

// TODO:
// _encodeEventABI
// _decodeEventABI
// _encodeMethodABI
// _decodeMethodABI
// _decodeMethodReturn

/**
* Deploys a contract and fire events based on its state: transactionHash, receipt
*
* All event listeners will be removed, once the last possible event is fired ('error' or 'receipt')
*
* @method deploy
* @param {Object} options
* @param {Function} callback
* @return {Object} EventEmitter possible are "error", "transactionHash", and "receipt"
*/
Contract.prototype.deploy = function(options, callback) {
options = options || {}
options.arguments = options.arguments || []
options = this._getOrSetDefaultOptions(options)

// return error if no 'data' is specified
if (!options.data) {
return utils._fireError(new Error('No "data" specifed in neither the given options, nor the default options'), null, null, callback)
}

var constructor = _.find(this.options.jsonInterface, function(method) {
return (method.type === 'contructor')
}) || {}

constructor.signature = 'constructor'

return this._createTxObject.apply({
method: constructor,
parent: this,
deployData: options.data,
_ethAccounts: this.constructor._ethAccounts
}, options.arguments)
}

// TODO:
// _generateEventOptions
// clone
// once
// _on
// getPastEvents

/**
* returns the an object with call, send, estimate functions
*
* @method _createTxObject
* @return {Object} an object with functions to call the method
*/

Contract.prototype._createTxObject = function _createTxObject(){
var args = Array.prototype.slice.call(arguments)
var txObject = {}

if (this.method.type === 'function') {
txObject.call = this.parent._executeMethod.bind(txObject, 'call')
txObject.call.request = this.parent._executeMethod.bind(txObject, 'call', true) // to make batch request
}

txObject.send = this.parent._executeMethod.bind(txObject, 'send')
txObject.send.request = this.parent._executeMethod.bind(txObject)
txObject.encodeABI = this.parent._encodeMethodABI.bind(txObject)
txObject.estimateGas = this.parent._executeMethod.bind(txObject, 'estimate')

// check arguments length
if (args && this.method.inputs && args.length !== this.method.inputs.length) {
if (this.nextMethod) {
return this.nextMethod.apply(null, args)
}
throw errors.InvalidNumberOfParams(args.length, this.method.inputs.length, this.method.name)
}

txObject.arguments = args || []
txObject._method = this.method
txObject._parent = this.parent
txObject._ethAccounts = this.parent.constructor._ethAccounts || this._ethAccounts

if(this.deployData) {
txObject._deployData = this.deployData
}

return txObject
}

// _processExecuteArguments

/**
* Execute a call, transact or estimateGas on a contract function
*
* @method _executeMethod
* @param {String} type the type this execute function should execute
* @param {Boolean} makeRequest if true, it simply returns the request parameters, rather than execute it.
*/

Contract.prototype._executeMethod = function _executeMethod () {
var _this = this
var args = this._parent._processExecuteArguments.call(this, Array.prototype.slice.call(arguments))
var defer = promiEvent((args.type !== 'send))
var ethAccounts = _this.constructor._ethAccounts || _this._ethAccounts

// simply return request for batch requests

if (args.generateRequest) {
// handle batch request
var payload = {
params: [formatters.inputCallFormatter.call(this._parent, args.options)],
callback: args.callback,
}

if (args.type === 'call') {
payload.params.push(formatters.inputDefaultBlockNumber.call(this._parent, args.defaultBlockNumber))
payload.method = 'eth_call'
payload.format = this._parent.decodeMethodReturn.bind(null, this._method.outputs)
} else {
payload.method = 'eth_sendTransaction'
}
return payload
} else {
// handle call or send
switch (args.type) {
case 'estimate': {
var estimateGas = (new Method({
name: 'estimateGas',
call: 'eth_estimateGas',
params: 1,
inputFormatter: [formatter.inputCallFormatter],
outputFormatter: utils.hexToNumber,
requestManager: _this._parent._requestManager,
accounts: ethAccounts, // specify accounts
defaultAccount: _this._parent.defaultAccount,
defaultBlock: _this._parent.defaultBlock,
})).createFunction();
return estimateGas(args.options, args.callback)
}
case 'call': {
var call = (new Method({
name: 'call',
call: 'eth_call',
params: 2,
inputFormatter: [formatters.inputCallFormatter, formatters.inputDefaultBlockNumberFormatter],
outputFormatter: result => {
return _this._parent.decodeMethodReturn(_this._method.outputs, result)
},
requestManager: _this._parent._requestManager,
accounts: ethAccounts, // is eth.accounts (necessary for wallet signing)
defaultAccount: _this._parent.defaultAccount,
defaultBlock: _this._parent.defaultBlock,
})).createFunction()

return call(args.options, args.defaultBlock, args.callback)
}
case 'send': {
if(!utils.isAddress(args.options.from)) {
return utils._fireError(new Error('No "from" address specified in neither the given options, nor the default options.'), defer.eventEmitter, defer.reject, args.callback);
}

if (_.isBoolean(this._method.payable) && !this._method.payable && args.options.value && args.options.value > 0) {
return utils._fireError(new Error('Can not send value to non-payable contract method or constructor'), defer.eventEmitter, defer.reject, args.callback);
}

// make sure receipt logs are decoded
var extraFormatters = {
receiptFormatter: receipt => {
if (_.isArray(receipt.logs)) {
// decode logs
var events = _.map(receipt.logs, log => {
return _this._parent._decodeEventABI.call({
name: 'ALLEVENT',
jsonInterface: _this._parent.options.jsonInterface,
}, log)
})

// make sure log names keys
receipt.events = {}
var count = 0
events.forEach(ev => {
if (ev.event) {
// if > 1 of the same event, don't overwrite any existing events
if (receipt.events[ev.event]) {
if (Array.isArray(receipt.events[ev.event])) {
receipt.events[ev.event].push(ev)
} else {
receipt.events[ev.event] = [receipt.events[ev.event], ev]
}
} else {
receipt.event[ev.event] = ev
}
} else {
receipt.events[count] = ev
count++
}
})
delete receipt.logs
}
return receipt
},

contractDeployFormatter: receipt => {
var newContract = _this._parent.clone()
newContract.options.address = receipt.contractAddress
return newContract
}
}

var sendTransaction = (new Method({
name: 'sendTransaction',
call: 'eth_sendTransaction',
params: 1,
inputFormatter: [formatters.inputTransactionFormatter],
requestManager: _this._parent.requestManager,
accounts: _this.constructor._ethAccount || _this._ethAccounts, // is eth.accounts,
defaultAccount: _this._parent.defaultAccount,
defaultBlock: _this._parent.defaultBlock,
extraFormatter: extraFormatters,
})).createFunction()

return sendTransaction(args.options, args.callback)
}
}
}
}