.. _eth-abi: .. include:: include_announcement.rst ============ web3.eth.abi ============ The ``web3-eth-abi`` package allows you to de- and encode parameters from a ABI (Application Binary Interface). This will be used for calling functions of a deployed smart-contract. .. code-block:: javascript import {AbiCoder} from 'web3-eth-abi'; const abiCoder = new AbiCoder(); // or using the web3 umbrella package import Web3 from 'web3'; const web3 = new Web3(Web3.givenProvider || 'ws://some.local-or-remote.node:8546', null, options); // -> web3.eth.abi ------------------------------------------------------------------------------ encodeFunctionSignature ===================== .. code-block:: javascript web3.eth.abi.encodeFunctionSignature(functionName); Encodes the function name to its ABI signature, which are the first 4 bytes of the sha3 hash of the function name including types. ---------- Parameters ---------- 1. ``functionName`` - ``String|Object``: The function name to encode. or the :ref:`JSON interface ` object of the function. If string it has to be in the form ``function(type,type,...)``, e.g: ``myFunction(uint256,uint32[],bytes10,bytes)`` ------- Returns ------- ``String`` - The ABI signature of the function. ------- Example ------- .. code-block:: javascript // From a JSON interface object web3.eth.abi.encodeFunctionSignature({ name: 'myMethod', type: 'function', inputs: [{ type: 'uint256', name: 'myNumber' },{ type: 'string', name: 'myString' }] }) > 0x24ee0097 // Or string web3.eth.abi.encodeFunctionSignature('myMethod(uint256,string)') > '0x24ee0097' ------------------------------------------------------------------------------ encodeEventSignature ===================== .. code-block:: javascript web3.eth.abi.encodeEventSignature(eventName); Encodes the event name to its ABI signature, which are the sha3 hash of the event name including input types. ---------- Parameters ---------- 1. ``eventName`` - ``String|Object``: The event name to encode. or the :ref:`JSON interface ` object of the event. If string it has to be in the form ``event(type,type,...)``, e.g: ``myEvent(uint256,uint32[],bytes10,bytes)`` ------- Returns ------- ``String`` - The ABI signature of the event. ------- Example ------- .. code-block:: javascript web3.eth.abi.encodeEventSignature('myEvent(uint256,bytes32)') > 0xf2eeb729e636a8cb783be044acf6b7b1e2c5863735b60d6daae84c366ee87d97 // or from a json interface object web3.eth.abi.encodeEventSignature({ name: 'myEvent', type: 'event', inputs: [{ type: 'uint256', name: 'myNumber' },{ type: 'bytes32', name: 'myBytes' }] }) > 0xf2eeb729e636a8cb783be044acf6b7b1e2c5863735b60d6daae84c366ee87d97 ------------------------------------------------------------------------------ encodeParameter ===================== .. code-block:: javascript web3.eth.abi.encodeParameter(type, parameter); Encodes a parameter based on its type to its ABI representation. ---------- Parameters ---------- 1. ``type`` - ``String|Object``: The type of the parameter, see the `solidity documentation `_ for a list of types. 2. ``parameter`` - ``Mixed``: The actual parameter to encode. ------- Returns ------- ``String`` - The ABI encoded parameter. ------- Example ------- .. code-block:: javascript web3.eth.abi.encodeParameter('uint256', '2345675643'); > "0x000000000000000000000000000000000000000000000000000000008bd02b7b" web3.eth.abi.encodeParameter('uint256', '2345675643'); > "0x000000000000000000000000000000000000000000000000000000008bd02b7b" web3.eth.abi.encodeParameter('bytes32', '0xdf3234'); > "0xdf32340000000000000000000000000000000000000000000000000000000000" web3.eth.abi.encodeParameter('bytes', '0xdf3234'); > "0x00000000000000000000000000000000000000000000000000000000000000200000000000000000000000000000000000000000000000000000000000000003df32340000000000000000000000000000000000000000000000000000000000" web3.eth.abi.encodeParameter('bytes32[]', ['0xdf3234', '0xfdfd']); > "00000000000000000000000000000000000000000000000000000000000000200000000000000000000000000000000000000000000000000000000000000002df32340000000000000000000000000000000000000000000000000000000000fdfd000000000000000000000000000000000000000000000000000000000000" ------------------------------------------------------------------------------ encodeParameters ===================== .. code-block:: javascript web3.eth.abi.encodeParameters(typesArray, parameters); Encodes a function parameters based on its :ref:`JSON interface ` object. ---------- Parameters ---------- 1. ``typesArray`` - ``Array|Object``: An array with types or a :ref:`JSON interface ` of a function. See the `solidity documentation `_ for a list of types. 2. ``parameters`` - ``Array``: The parameters to encode. ------- Returns ------- ``String`` - The ABI encoded parameters. ------- Example ------- .. code-block:: javascript web3.eth.abi.encodeParameters(['uint256','string'], ['2345675643', 'Hello!%']); > "0x000000000000000000000000000000000000000000000000000000008bd02b7b0000000000000000000000000000000000000000000000000000000000000040000000000000000000000000000000000000000000000000000000000000000748656c6c6f212500000000000000000000000000000000000000000000000000" web3.eth.abi.encodeParameters(['uint8[]','bytes32'], [['34','434'], '0x324567fff']); > "0x0" ------------------------------------------------------------------------------ encodeFunctionCall ===================== .. code-block:: javascript web3.eth.abi.encodeFunctionCall(jsonInterface, parameters); Encodes a function call using its :ref:`JSON interface ` object and given parameters. ---------- Parameters ---------- 1. ``jsonInterface`` - ``Object``: The :ref:`JSON interface ` object of a function. 2. ``parameters`` - ``Array``: The parameters to encode. ------- Returns ------- ``String`` - The ABI encoded function call. Means function signature + parameters. ------- Example ------- .. code-block:: javascript web3.eth.abi.encodeFunctionCall({ name: 'myMethod', type: 'function', inputs: [{ type: 'uint256', name: 'myNumber' },{ type: 'string', name: 'myString' }] }, ['2345675643', 'Hello!%']); > "0x24ee0097000000000000000000000000000000000000000000000000000000008bd02b7b0000000000000000000000000000000000000000000000000000000000000040000000000000000000000000000000000000000000000000000000000000000748656c6c6f212500000000000000000000000000000000000000000000000000" ------------------------------------------------------------------------------ decodeParameter ===================== .. code-block:: javascript web3.eth.abi.decodeParameter(type, hexString); Decodes an ABI encoded parameter to its JavaScript type. ---------- Parameters ---------- 1. ``type`` - ``String|Object``: The type of the parameter, see the `solidity documentation `_ for a list of types. 2. ``hexString`` - ``String``: The ABI byte code to decode. ------- Returns ------- ``Mixed`` - The decoded parameter. ------- Example ------- .. code-block:: javascript web3.eth.abi.decodeParameter('uint256', '0x0000000000000000000000000000000000000000000000000000000000000010'); > "16" web3.eth.abi.decodeParameter('string', '0x0000000000000000000000000000000000000000000000000000000000000020000000000000000000000000000000000000000000000000000000000000000848656c6c6f212521000000000000000000000000000000000000000000000000'); > "Hello!%!" web3.eth.abi.decodeParameter('string', '0x0000000000000000000000000000000000000000000000000000000000000020000000000000000000000000000000000000000000000000000000000000000848656c6c6f212521000000000000000000000000000000000000000000000000'); > "Hello!%!" ------------------------------------------------------------------------------ decodeParameters ===================== .. code-block:: javascript web3.eth.abi.decodeParameters(typesArray, hexString); Decodes ABI encoded parameters to its JavaScript types. ---------- Parameters ---------- 1. ``typesArray`` - ``Array|Object``: An array with types or a :ref:`JSON interface ` outputs array. See the `solidity documentation `_ for a list of types. 2. ``hexString`` - ``String``: The ABI byte code to decode. ------- Returns ------- ``Object`` - The result object containing the decoded parameters. ------- Example ------- .. code-block:: javascript web3.eth.abi.decodeParameters(['string', 'uint256'], '0x000000000000000000000000000000000000000000000000000000000000004000000000000000000000000000000000000000000000000000000000000000ea000000000000000000000000000000000000000000000000000000000000000848656c6c6f212521000000000000000000000000000000000000000000000000'); > Result { '0': 'Hello!%!', '1': '234' } web3.eth.abi.decodeParameters([{ type: 'string', name: 'myString' },{ type: 'uint256', name: 'myNumber' }], '0x000000000000000000000000000000000000000000000000000000000000004000000000000000000000000000000000000000000000000000000000000000ea000000000000000000000000000000000000000000000000000000000000000848656c6c6f212521000000000000000000000000000000000000000000000000'); > Result { '0': 'Hello!%!', '1': '234', myString: 'Hello!%!', myNumber: '234' } ------------------------------------------------------------------------------ decodeLog ===================== .. code-block:: javascript web3.eth.abi.decodeLog(inputs, hexString, topics); Decodes ABI encoded log data and indexed topic data. ---------- Parameters ---------- 1. ``inputs`` - ``Array``: A :ref:`JSON interface ` inputs array. See the `solidity documentation `_ for a list of types. 2. ``hexString`` - ``String``: The ABI byte code in the ``data`` field of a log. 3. ``topics`` - ``Array``: An array with the index parameter topics of the log, without the topic[0] if its a non-anonymous event, otherwise with topic[0]. ------- Returns ------- ``Object`` - The result object containing the decoded parameters. ------- Example ------- .. code-block:: javascript web3.eth.abi.decodeLog([{ type: 'string', name: 'myString' },{ type: 'uint256', name: 'myNumber', indexed: true },{ type: 'uint8', name: 'mySmallNumber', indexed: true }], '0x0000000000000000000000000000000000000000000000000000000000000020000000000000000000000000000000000000000000000000000000000000000748656c6c6f252100000000000000000000000000000000000000000000000000', ['0x000000000000000000000000000000000000000000000000000000000000f310', '0x0000000000000000000000000000000000000000000000000000000000000010']); > Result { '0': 'Hello%!', '1': '62224', '2': '16', myString: 'Hello%!', myNumber: '62224', mySmallNumber: '16' }