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https://github.com/xclud/web3dart

Ethereum library, written in Dart.
https://github.com/xclud/web3dart

blockchain dart ethereum flutter web3

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Ethereum library, written in Dart.

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A dart library that connects to interact with the Ethereum blockchain. It connects

to an Ethereum node to send transactions, interact with smart contracts and much

more!



## Features



- Connect to an Ethereum node with the rpc-api, call common methods

- Send signed Ethereum transactions

- Generate private keys, setup new Ethereum addresses

- Call functions on smart contracts and listen for contract events

- Code generation based on smart contract ABI for easier interaction



### TODO



- Encode all supported solidity types, although only (u)fixed,

  which are not commonly used, are not supported at the moment.



## Usage



### Credentials and Wallets



In order to send transactions on the Ethereum network, some credentials

are required. The library supports raw private keys and v3 wallet files.



```dart

import 'dart:math'; //used for the random number generator



import 'package:web3dart/web3dart.dart';

// You can create Credentials from private keys

Credentials fromHex = EthPrivateKey.fromHex("c87509a[...]dc0d3");



// Or generate a new key randomly

var rng = Random.secure();

Credentials random = EthPrivateKey.createRandom(rng);



// In either way, the library can derive the public key and the address

// from a private key:

var address = credentials.address;

print(address.hex);

```



Another way to obtain `Credentials` which the library uses to sign

transactions is the usage of a wallet file. Wallets store a private

key securely and require a password to unlock. The library has experimental

support for version 3 wallets commonly generated by other Ethereum clients:



```dart

import 'dart:io';

import 'package:web3dart/web3dart.dart';



String content = File("wallet.json").readAsStringSync();

Wallet wallet = Wallet.fromJson(content, "testpassword");



Credentials unlocked = wallet.privateKey;

// You can now use these credentials to sign transactions or messages

```



You can also create Wallet files with this library. To do so, you first need

the private key you want to encrypt and a desired password. Then, create

your wallet with



```dart

Wallet wallet = Wallet.createNew(credentials, "password", random);

print(wallet.toJson());

```



You can also write `wallet.toJson()` into a file which you can later open

with [MyEtherWallet](https://www.myetherwallet.com/#view-wallet-info)

(select Keystore / JSON File) or other Ethereum clients like geth.



#### Custom credentials



If you want to integrate `web3dart` with other wallet providers, you can implement

`Credentials` and override the appropriate methods.



### Connecting to an RPC server



The library won't send signed transactions to miners itself. Instead,

it relies on an RPC client to do that. You can use a public RPC API like

[infura](https://infura.io/), setup your own using [geth](https://github.com/ethereum/go-ethereum/wiki/geth)

or, if you just want to test things out, use a private testnet with

[truffle](https://www.trufflesuite.com/) and [ganache](https://www.trufflesuite.com/ganache). All these options will give you

an RPC endpoint to which the library can connect.



```dart

import 'package:http/http.dart'; //You can also import the browser version

import 'package:web3dart/web3dart.dart';



var apiUrl = "http://localhost:7545"; //Replace with your API



var httpClient = Client();

var ethClient = Web3Client(apiUrl, httpClient);



var credentials = EthPrivateKey.fromHex("0x...");

var address = credentials.address;



// You can now call rpc methods. This one will query the amount of Ether you own

EtherAmount balance = ethClient.getBalance(address);

print(balance.getValueInUnit(EtherUnit.ether));

```



## Sending transactions



Of course, this library supports creating, signing and sending Ethereum

transactions:



```dart

import 'package:web3dart/web3dart.dart';



/// [...], you need to specify the url and your client, see example above

var ethClient = Web3Client(apiUrl, httpClient);



var credentials = EthPrivateKey.fromHex("0x...");



await client.sendTransaction(

  credentials,

  Transaction(

    to: EthereumAddress.fromHex('0xC91...3706'),

    gasPrice: EtherAmount.inWei(BigInt.one),

    maxGas: 100000,

    value: EtherAmount.fromUnitAndValue(EtherUnit.ether, 1),

  ),

);

```



Missing data, like the gas price, the sender and a transaction nonce will be

obtained from the connected node when not explicitly specified. If you only need

the signed transaction but don't intend to send it, you can use

`client.signTransaction`.



### Smart contracts



The library can parse the abi of a smart contract and send data to it. It can also

listen for events emitted by smart contracts. See [this file](https://github.com/xclud/web3dart/blob/development/example/contracts.dart)

for an example.



### Dart Code Generator



By using [Dart's build system](https://github.com/dart-lang/build/), web3dart can

generate Dart code to easily access smart contracts.



Install web3dart_builders package



```dart

pub add web3dart_builders --dev

```



To use this feature, put a contract abi json somewhere into `lib/`.

The filename has to end with `.abi.json`.

Then, add a `dev_dependency` on the `build_runner` package and run



```dart

pub run build_runner build

```



You'll now find a `.g.dart` file containing code to interact with the contract.



#### Optional: Ignore naming suggestions for generated files



If importing contract ABIs with function names that don't follow dart's naming conventions, the dart analyzer will (by default) be unhappy about it, and show warnings.

This can be mitigated by excluding all the generated files from being analyzed.  

Note that this has the side effect of suppressing serious errors as well, should there exist any. (There shouldn't as these files are automatically generated).



Create a file named `analysis_options.yaml` in the root directory of your project:



```dart

analyzer:

  exclude: 

    - '**/*.g.dart'

```



See [Customizing static analysis](https://dart.dev/guides/language/analysis-options) for advanced options.



## Feature requests and bugs



Please file feature requests and bugs at the [issue tracker][tracker].

If you want to contribute to this library, please submit a Pull Request.



[tracker]: https://github.com/xclud/web3dart/issues/new



## Testing



```dart

dart test test

```