Contract Loader¶

Class Name	ContractLoader
Extends	Logger
Source	contract-loader.ts
Examples	contract-loader.spec.ts

The ContractLoader is used when loading contracts without a DBCP description or when creating new contracts via bytecode. In both cases additional information has to be passed to the ContractLoader constructor.

Loading contracts requires an abi interface as a JSON string and creating new contracts requires the bytecode as hex string. Compiling Ethereum smart contracts with solc provides these.

Abis, that are included by default are:

AbstractENS
Described
EventHub
Owned
PublicResolver

Bytecode for these contracts is included by default:

Described
Owned

Following is an example for loading a contract with a custom abi. The contract is a Greeter Contract and a shortened interface containing only the greet function is used here.

They can be side-loaded into an existing contract loader instance, e.g. into a runtime:

runtime.contractLoader.contracts['Greeter'] = {
  "interface": "[{\"constant\":true,\"inputs\":[],\"name\":\"greet\",\"outputs\":[{\"name\":\"\",\"type\":\"string\"}],\"payable\":false,\"stateMutability\":\"view\",\"type\":\"function\"}]",
};

getCompiledContract¶

contractLoader.getCompiledContract(name);

gets contract from a solc compilation

Parameters¶

name - string: Contract name

Returns¶

any: The compiled contract.

Example¶

const address = '0x9c0Aaa728Daa085Dfe85D3C72eE1c1AdF425be49';
const accountId = '0x000000000000000000000000000000000000beef';
const description = await runtime.description.getDescription(address, accountId);
console.dir(description);
// Output:
// { public:
//    { name: 'DBCP sample greeter',
//      description: 'smart contract with a greeting message and a data property',
//      author: 'dbcp test',
//      tags: [ 'example', 'greeter' ],
//      version: '0.1.0',
//      abis: { own: [Array] } } }

loadContract¶

contractLoader.loadContract(name, address);

creates a contract instance that handles a smart contract at a given address

Parameters¶

name - string: Contract name
address - string: Contract address

Returns¶

any: contract instance.

Example¶

const greeter = runtime.contractLoader.loadContract('Greeter', '0x9c0Aaa728Daa085Dfe85D3C72eE1c1AdF425be49');