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# ethereum-input-data-decoder > Ethereum smart contract transaction input data decoder [![License](http://img.shields.io/badge/license-MIT-blue.svg)](https://raw.githubusercontent.com/miguelmota/ethereum-input-data-decoder/master/LICENSE) [![Build Status](https://travis-ci.org/miguelmota/ethereum-input-data-decoder.svg?branch=master)](https://travis-ci.org/miguelmota/ethereum-input-data-decoder) [![dependencies Status](https://david-dm.org/miguelmota/ethereum-input-data-decoder/status.svg)](https://david-dm.org/miguelmota/ethereum-input-data-decoder) [![NPM version](https://badge.fury.io/js/ethereum-input-data-decoder.svg)](http://badge.fury.io/js/ethereum-input-data-decoder) [![PRs Welcome](https://img.shields.io/badge/PRs-welcome-brightgreen.svg)](#contributing) ## Demo [https://lab.miguelmota.com/ethereum-input-data-decoder](https://lab.miguelmota.com/ethereum-input-data-decoder) ## Install ```bash npm install ethereum-input-data-decoder ``` ## Getting started Pass [ABI](https://github.com/ethereum/wiki/wiki/Ethereum-Contract-ABI) file path to decoder constructor: ```javascript const InputDataDecoder = require('ethereum-input-data-decoder'); const decoder = new InputDataDecoder(`${__dirname}/abi.json`); ``` Alternatively, you can pass ABI array object to constructor; ```javascript const abi = [{ ... }] const decoder = new InputDataDecoder(abi); ``` [example abi](./test/abi.json) Then you can decode input data: ```javascript const data = `0x67043cae0000000000000000000000005a9dac9315fdd1c3d13ef8af7fdfeb522db08f020000000000000000000000000000000000000000000000000000000058a20230000000000000000000000000000000000000000000000000000000000040293400000000000000000000000000000000000000000000000000000000000000a0f3df64775a2dfb6bc9e09dced96d0816ff5055bf95da13ce5b6c3f53b97071c800000000000000000000000000000000000000000000000000000000000000034254430000000000000000000000000000000000000000000000000000000000`; const result = decoder.decodeData(data); console.log(result); ``` ```text { "method": "registerOffChainDonation", "types": [ "address", "uint256", "uint256", "string", "bytes32" ], "inputs": [ , , , "BTC", ], "names": [ "addr", "timestamp", "chfCents", "currency", "memo" ] } ``` Example using input response from [web3.getTransaction](https://github.com/ethereum/wiki/wiki/JavaScript-API#web3ethgettransaction): ```javascript web3.eth.getTransaction(txHash, (error, txResult) => { const result = decoder.decodeData(txResult.input); console.log(result); }); ``` ### Decoding tuple and tuple[] types Where `OrderData` is ```solidity struct OrderData { uint256 amount; address buyer; } ``` Decoding input to a method `someMethod(address,OrderData,OrderData[])` returns data in format ```js { method: 'someMethod', types: ['address', '(uint256,address)', '(uint256,address)[]'], inputs: [ '0x81c55017F7Ce6E72451cEd49FF7bAB1e3DF64d0C', [100, '0xA37dE6790861B5541b0dAa7d0C0e651F44c6f4D9'] [[274, '0xea674fdde714fd979de3edf0f56aa9716b898ec8']] ], names: ['sender', ['order', ['amount', 'buyer']], ['allOrders', ['amount', 'buyer']]] } ``` - In the `types` field, tuples are represented as a string containing types contained in the tuple - In the `inputs` field, tuples are represented as an array containing values contained in the tuple - In the `names` field, tuples are represented as an array with 2 items. Item 1 is the name of the tuple, item 2 is an array containing the names of the values contained in the tuple. ### Decoding Big Numbers All numbers are returned in [big number](https://github.com/indutny/bn.js) format to preserve precision. Here's an example of how to convert the big number to a human readable format. ```js console.log(result.inputs[0].toString(10)) // "5" console.log(result.inputs[0].toNumber()) // 55 ``` Please keep in mind that JavaScript only supports numbers up to 64 bits. Solidity numbers can be up to 256 bits, so you run the risk of truncation when casting or having the big number library error out when trying to parse a large number to a JavaScript Number type. ```js const n = new BN("543534254523452352345234523455") console.log(n.toString(10)) // "543534254523452352345234523455" console.log(n.toNumber()) // ERROR! ``` ## CLI ## Install ```bash npm install -g ethereum-input-data-decoder ``` ### Usage ```bash $ ethereum_input_data_decoder --help Ethereum smart contract transaction input data decoder Usage $ ethereum_input_data_decoder [flags] [input] Options --abi, -a ABI file path --input, -i Input data file path Examples $ ethereum_input_data_decoder --abi token.abi --input data.txt $ ethereum_input_data_decoder --abi token.abi "0x23b872dd..." ``` ### Example Pass ABI file and input data as file: ```bash $ ethereum_input_data_decoder --abi abi.json --input data.tx method registerOffChainDonation address addr 0x5a9dac9315fdd1c3d13ef8af7fdfeb522db08f02 uint256 timestamp 1487012400 uint256 chfCents 4204852 string currency BTC bytes32 memo 0xf3df64775a2dfb6bc9e09dced96d0816ff5055bf95da13ce5b6c3f53b97071c8 ``` Pass ABI file and input data as string: ```bash $ ethereum_input_data_decoder --abi abi.json 0x67043cae0...000000 method registerOffChainDonation address addr 0x5a9dac9315fdd1c3d13ef8af7fdfeb522db08f02 uint256 timestamp 1487012400 uint256 chfCents 4204852 string currency BTC bytes32 memo 0xf3df64775a2dfb6bc9e09dced96d0816ff5055bf95da13ce5b6c3f53b97071c8 ``` You can also pipe the input data: ```bash $ cat data.txt | ethereum_input_data_decoder --abi abi.json method registerOffChainDonation address addr 0x5a9dac9315fdd1c3d13ef8af7fdfeb522db08f02 uint256 timestamp 1487012400 uint256 chfCents 4204852 string currency BTC bytes32 memo 0xf3df64775a2dfb6bc9e09dced96d0816ff5055bf95da13ce5b6c3f53b97071c8 ``` ## Test ```bash npm test ``` ## Development 1. Clone repository: ```bash git clone git@github.com:miguelmota/ethereum-input-data-decoder.git cd ethereum-input-data-decoder/ ``` 2. Install dependencies: ```bash npm install ``` 3. Make changes. 4. Run tests: ```bash npm test ``` 5. Run linter: ```bash npm run lint ``` 5. Build: ```bash npm run build ``` ## Contributing Pull requests are welcome! For contributions please create a new branch and submit a pull request for review. Many thanks to all the [contributors](https://github.com/miguelmota/ethereum-input-data-decoder/graphs/contributors) for making this a better library for everyone 🙏 ## FAQ - Q: How can I retrieve the ABI? - A: You can generate the ABI from the solidity source files using the [Solidity Compiler](http://solidity.readthedocs.io/en/develop/installing-solidity.html). ```bash solc --abi MyContract.sol -o build ``` - Q: Can this library decode contract creation input data? - A: Yes, it can decode contract creation input data. - Q: Does this library support ABIEncoderV2? - A: Yes, but it's buggy. Please submit a [bug report](https://github.com/miguelmota/ethereum-input-data-decoder/issues/new) if you encounter issues. ## License [MIT](LICENSE)