json interface
The json interface is a json object describing the Application Binary Interface (ABI) for a smart contract. Using this json interface, web3.js is able to create JavaScript object representing the smart contract and its methods and events using the web3.eth.Contract object.
Specification
Functions:
type
:"function"
,"constructor"
(can be omitted, defaulting to"function"
;"fallback"
also possible but not relevant in web3.js).name
: the name of the function (only present for function types).constant
:true
if function is specified to not modify the blockchain state.payable
:true
if function accepts ether, defaults tofalse
stateMutability
: a string with one of the following values:pure
(specified to not read blockchain state)view
(same asconstant
above)nonpayable
andpayable
(same aspayable
above)
inputs
: an array of objects, each of which contains:name
: the name of the parametertype
: the canonical type of the parameter
outputs
: an array of objects same asinputs
, can be omitted if no outputs exist.
Events:
type
: always"event"
name
: the name of the event.inputs
: an array of objects, each of which contains:name
: the name of the parameter.type
: the canonical type of the parameter.indexed
:true
if the field is part of the log's topics,false
if it one of the log's data segment.
anonymous
:true
if the event was declared asanonymous
.
Example:
contract Test {
uint a;
address d = 0x12345678901234567890123456789012;
function Test(uint testInt) { a = testInt;}
event Event(uint indexed b, bytes32 c);
event Event2(uint indexed b, bytes32 c);
function foo(uint b, bytes32 c) returns(address) {
Event(b, c);
return d;
}
}
// would result in the JSON:
[{
"type":"constructor",
"payable":false,
"stateMutability":"nonpayable"
"inputs":[{"name":"testInt","type":"uint256"}],
},{
"type":"function",
"name":"foo",
"constant":false,
"payable":false,
"stateMutability":"nonpayable",
"inputs":[{"name":"b","type":"uint256"}, {"name":"c","type":"bytes32"}],
"outputs":[{"name":"","type":"address"}]
},{
"type":"event",
"name":"Event",
"inputs":[{"indexed":true,"name":"b","type":"uint256"}, {"indexed":false,"name":"c","type":"bytes32"}],
"anonymous":false
},{
"type":"event",
"name":"Event2",
"inputs":[{"indexed":true,"name":"b","type":"uint256"},{"indexed":false,"name":"c","type":"bytes32"}],
"anonymous":false
}]
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