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John edited this page May 28, 2019 · 2 revisions

web3-eth-abi

The web3.eth.abi object makes it easy to interact with Solidity based ABIs on the Aion blockchain.

The web3.eth.abi functions let you decode and encode parameters to ABI (Application Binary Interface) for function calls to the FastVM.

encodeFunctionSignature

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 JSON interface <glossary-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

// 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

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 JSON interface <glossary-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

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

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

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"

web3.eth.abi.encodeParameter(
    {
        "ParentStruct": {
            "propertyOne": 'uint256',
            "propertyTwo": 'uint256',
            "childStruct": {
                "propertyOne": 'uint256',
                "propertyTwo": 'uint256'
            }
        }
    },
    {
        "propertyOne": 42,
        "propertyTwo": 56,
        "childStruct": {
            "propertyOne": 45,
            "propertyTwo": 78
        }
    }
);
> "0x000000000000000000000000000000000000000000000000000000000000002a0000000000000000000000000000000000000000000000000000000000000038000000000000000000000000000000000000000000000000000000000000002d000000000000000000000000000000000000000000000000000000000000004e"

encodeParameters

web3.eth.abi.encodeParameters(typesArray, parameters);

Encodes a function parameters based on its JSON interface <glossary-json-interface> object.

Parameters

  1. typesArray - Array<String|Object>|Object: An array with types or a JSON interface <glossary-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

web3.eth.abi.encodeParameters(['uint256','string'], ['2345675643', 'Hello!%']);
> "0x000000000000000000000000000000000000000000000000000000008bd02b7b0000000000000000000000000000000000000000000000000000000000000040000000000000000000000000000000000000000000000000000000000000000748656c6c6f212500000000000000000000000000000000000000000000000000"

web3.eth.abi.encodeParameters(['uint8[]','bytes32'], [['34','434'], '0x324567fff']);
> "0x0

web3.eth.abi.encodeParameters(
    [
        'uint8[]',
        {
            "ParentStruct": {
                "propertyOne": 'uint256',
                "propertyTwo": 'uint256',
                "ChildStruct": {
                    "propertyOne": 'uint256',
                    "propertyTwo": 'uint256'
                }
            }
        }
    ],
    [
        ['34','434'],
        {
            "propertyOne": '42',
            "propertyTwo": '56',
            "ChildStruct": {
                "propertyOne": '45',
                "propertyTwo": '78'
            }
        }
    ]
);
> "0x00000000000000000000000000000000000000000000000000000000000000a0000000000000000000000000000000000000000000000000000000000000002a0000000000000000000000000000000000000000000000000000000000000038000000000000000000000000000000000000000000000000000000000000002d000000000000000000000000000000000000000000000000000000000000004e0000000000000000000000000000000000000000000000000000000000000002000000000000000000000000000000000000000000000000000000000000002a0000000000000000000000000000000000000000000000000000000000000018"

encodeFunctionCall

web3.eth.abi.encodeFunctionCall(jsonInterface, parameters);

Encodes a function call using its JSON interface <glossary-json-interface> object and given paramaters.

Parameters

  1. jsonInterface - Object: The JSON interface <glossary-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

web3.eth.abi.encodeFunctionCall({
    name: 'myMethod',
    type: 'function',
    inputs: [{
        type: 'uint256',
        name: 'myNumber'
    },{
        type: 'string',
        name: 'myString'
    }]
}, ['2345675643', 'Hello!%']);
> "0x24ee0097000000000000000000000000000000000000000000000000000000008bd02b7b0000000000000000000000000000000000000000000000000000000000000040000000000000000000000000000000000000000000000000000000000000000748656c6c6f212500000000000000000000000000000000000000000000000000"

decodeParameter

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

web3.eth.abi.decodeParameter('uint256', '0x0000000000000000000000000000000000000000000000000000000000000010');
> "16"

web3.eth.abi.decodeParameter('string', '0x0000000000000000000000000000000000000000000000000000000000000020000000000000000000000000000000000000000000000000000000000000000848656c6c6f212521000000000000000000000000000000000000000000000000');
> "Hello!%!"

web3.eth.abi.decodeParameter('string', '0x0000000000000000000000000000000000000000000000000000000000000020000000000000000000000000000000000000000000000000000000000000000848656c6c6f212521000000000000000000000000000000000000000000000000');
> "Hello!%!"

web3.eth.abi.decodeParameter(
    {
        "ParentStruct": {
          "propertyOne": 'uint256',
          "propertyTwo": 'uint256',
          "childStruct": {
            "propertyOne": 'uint256',
            "propertyTwo": 'uint256'
          }
        }
    },

, '0x000000000000000000000000000000000000000000000000000000000000002a0000000000000000000000000000000000000000000000000000000000000038000000000000000000000000000000000000000000000000000000000000002d000000000000000000000000000000000000000000000000000000000000004e');
> {
    '0': {
        '0': '42',
        '1': '56',
        '2': {
            '0': '45',
            '1': '78',
            'propertyOne': '45',
            'propertyTwo': '78'
        },
        'childStruct': {
            '0': '45',
            '1': '78',
            'propertyOne': '45',
            'propertyTwo': '78'
        },
        'propertyOne': '42',
        'propertyTwo': '56'
    },
    'ParentStruct': {
        '0': '42',
        '1': '56',
        '2': {
            '0': '45',
            '1': '78',
            'propertyOne': '45',
            'propertyTwo': '78'
        },
        'childStruct': {
            '0': '45',
            '1': '78',
            'propertyOne': '45',
            'propertyTwo': '78'
        },
        'propertyOne': '42',
        'propertyTwo': '56'
    }
}

decodeParameters

web3.eth.abi.decodeParameters(typesArray, hexString);

Decodes ABI encoded parameters to its JavaScript types.

Parameters

  1. typesArray - Array<String|Object>|Object: An array with types or a JSON interface <glossary-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

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'
}

web3.eth.abi.decodeParameters([
  'uint8[]',
  {
    "ParentStruct": {
      "propertyOne": 'uint256',
      "propertyTwo": 'uint256',
      "childStruct": {
        "propertyOne": 'uint256',
        "propertyTwo": 'uint256'
      }
    }
  }
], '0x00000000000000000000000000000000000000000000000000000000000000a0000000000000000000000000000000000000000000000000000000000000002a0000000000000000000000000000000000000000000000000000000000000038000000000000000000000000000000000000000000000000000000000000002d000000000000000000000000000000000000000000000000000000000000004e0000000000000000000000000000000000000000000000000000000000000002000000000000000000000000000000000000000000000000000000000000002a0000000000000000000000000000000000000000000000000000000000000018');
> Result {
    '0': ['42', '24'],
    '1': {
        '0': '42',
        '1': '56',
        '2':
            {
                '0': '45',
                '1': '78',
                'propertyOne': '45',
                'propertyTwo': '78'
            },
        'childStruct':
            {
                '0': '45',
                '1': '78',
                'propertyOne': '45',
                'propertyTwo': '78'
            },
        'propertyOne': '42',
        'propertyTwo': '56'
    }
}

decodeLog

web3.eth.abi.decodeLog(inputs, hexString, topics);

Decodes ABI encoded log data and indexed topic data.

Parameters

  1. inputs - Object: A JSON interface <glossary-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

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'
}
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