Create USDT Wallet on ERC20 Dart - flutter
I want to understand for myself how to generate USDT ERC20 wallet in dart language. I found the web3dart library. But what does it take to generate a koschel using the 12-word phrase provided by the bip39 library? And I don’t understand, is it necessary to write a smart contract? I would like to see a small code example of how to generate a wallet. Many thanks.
Update:
I seem to have managed to generate a wallet. But how to make exactly USDT on ERC20?
var random = Random.secure();
var mnemonic = 'obvious width mechanic wheat cargo toe bike seek spirit jungle enlist thumb';
String mnemonicToSeedHex = bip39.mnemonicToSeedHex(mnemonic);
EthPrivateKey credentials = EthPrivateKey.fromHex(mnemonicToSeedHex);
Wallet wallet = Wallet.createNew(credentials, mnemonic, random);
var address = await credentials.extractAddress();
dev.log(address.hex);
Since USDT is an erc-20 token, you can use the erc-20 abi for contract interactions.
final _erc20ContractAbi = web3.ContractAbi.fromJson(
'[{"anonymous":false,"inputs":[{"indexed":true,"internalType":"address","name":"owner","type":"address"},{"indexed":true,"internalType":"address","name":"spender","type":"address"},{"indexed":false,"internalType":"uint256","name":"value","type":"uint256"}],"name":"Approval","type":"event"},{"anonymous":false,"inputs":[{"indexed":true,"internalType":"address","name":"from","type":"address"},{"indexed":true,"internalType":"address","name":"to","type":"address"},{"indexed":false,"internalType":"uint256","name":"value","type":"uint256"}],"name":"Transfer","type":"event"},{"inputs":[{"internalType":"address","name":"owner","type":"address"},{"internalType":"address","name":"spender","type":"address"}],"name":"allowance","outputs":[{"internalType":"uint256","name":"","type":"uint256"}],"stateMutability":"view","type":"function"},{"inputs":[{"internalType":"address","name":"spender","type":"address"},{"internalType":"uint256","name":"amount","type":"uint256"}],"name":"approve","outputs":[{"internalType":"bool","name":"","type":"bool"}],"stateMutability":"nonpayable","type":"function"},{"inputs":[{"internalType":"address","name":"account","type":"address"}],"name":"balanceOf","outputs":[{"internalType":"uint256","name":"","type":"uint256"}],"stateMutability":"view","type":"function"},{"inputs":[],"name":"decimals","outputs":[{"internalType":"uint8","name":"","type":"uint8"}],"stateMutability":"view","type":"function"},{"inputs":[],"name":"name","outputs":[{"internalType":"string","name":"","type":"string"}],"stateMutability":"view","type":"function"},{"inputs":[],"name":"symbol","outputs":[{"internalType":"string","name":"","type":"string"}],"stateMutability":"view","type":"function"},{"inputs":[],"name":"totalSupply","outputs":[{"internalType":"uint256","name":"","type":"uint256"}],"stateMutability":"view","type":"function"},{"inputs":[{"internalType":"address","name":"recipient","type":"address"},{"internalType":"uint256","name":"amount","type":"uint256"}],"name":"transfer","outputs":[{"internalType":"bool","name":"","type":"bool"}],"stateMutability":"nonpayable","type":"function"},{"inputs":[{"internalType":"address","name":"sender","type":"address"},{"internalType":"address","name":"recipient","type":"address"},{"internalType":"uint256","name":"amount","type":"uint256"}],"name":"transferFrom","outputs":[{"internalType":"bool","name":"","type":"bool"}],"stateMutability":"nonpayable","type":"function"}]',
'Erc20');
Now write a class to interact with each functions in the abi. You need to pass the contract address, web3client (infura or any other) and chainID (1 for ethereum mainnet)
class ERC20 extends web3.GeneratedContract {
ERC20({
required web3.EthereumAddress address,
required web3.Web3Client client,
int? chainId,
}) : super(web3.DeployedContract(_erc20ContractAbi, address), client,
chainId);
Now you can get the balance of your USDT by writing a balanceOf method inside the class like this,
Future<BigInt> balanceOf(
web3.EthereumAddress account, {
web3.BlockNum? atBlock,
}) async {
final function = self.abi.functions[2];
assert(checkSignature(function, '70a08231'));
final params = [account];
final response = await read(function, params, atBlock);
return (response[0] as BigInt);
}
Function to Transafer USDT tokens,
Future<String> transfer(
web3.EthereumAddress recipient,
BigInt amount, {
required web3.Credentials credentials,
web3.Transaction? transaction,
}) async {
final function = self.abi.functions[7];
assert(checkSignature(function, 'a9059cbb'));
final params = [recipient, amount];
return write(credentials, transaction, function, params);
}
Check out my article on Medium , Crypto-wallet app using flutter to get an idea on how to build your own erc-20 token and use flutter mobile application to build a wallet that can transfer the coins.
Related
appwrite list users search params
I am trying to use appwrite server sdk list users to get userid from an email.
The documentation says there is a search: option that can be used but no where does it say what the format of that String? is.
What is the format of the search: String? to only get a list of users whose email matches?
void main() { // Init SDK
Client client = Client();
Users users = Users(client);
client
.setEndpoint(endPoint) // Your API Endpoint
.setProject(projectID) // Your project ID
.setKey(apiKey) // Your secret API key
;
Future result = users.list(search: '<<<WHAT GOES HERE>>>');
}
:wave: Hello!
Thanks for bringing this question up, this is definitely not well documented, I'll note this down and try to make it clearer in the docs, but here's how you'd approach this in Dart:
final res = users.list(search: Query.equal('email',
'email#example.com'));
res.then((response) {
print(response.users[0].toMap());
}).catchError((error) {
print(error);
});
The Query object generates a query string, and works similar to how listDocument would work. The difference here is that it only takes a single query string instead of a list.
How to get AutoRefreshingAuthClient from AuthClient without any service account (Google Auth)
I need an AutoRefreshingAuthClient to use gsheet to play with authenticated users Google Sheet. I can get AuthClient using google_sign_in package. So, How can I get AutoRefreshingAuthClient from AuthClient in a flutter application without any service account? The reason I don't want to use a Service Account is, If I use a Service Account, all files are saved into this Service Account. But, I want to read, write and use Google Sheet from the authenticated user's account.
I ended up using googleapis instead. Seems like gsheets was made to work specifically with Service Accounts so even if you create a valid AutoRefreshingAuthClient it'll check to see if it's a Service Account.
Here's how I did it with the SheetsApi (The GoogleAuthClient class was found after a lot of searching on GitHub and multiple users had the same thing):
import 'package:http/http.dart' as http;
class GoogleAuthClient extends http.BaseClient {
final Map<String, String> _headers;
final http.Client _client = new http.Client();
GoogleAuthClient(this._headers);
Future<http.StreamedResponse> send(http.BaseRequest request) {
return _client.send(request..headers.addAll(_headers));
}
}
final client = GoogleAuthClient((await _googleSignIn.currentUser.authHeaders));
_SheetApi = sheets.SheetsApi(client);
There is as decent amount of overhead on our side with SheetsApi compared to GSheets. Like appending rows or simply naming your Spreadsheet requires more lines of code and/or objects:
// Sheet creation
sheets.Spreadsheet request = sheets.Spreadsheet.fromJson({
'properties': {
'title': "$title",
},
});
sheets.Spreadsheet sh = getSheetApi().spreadsheets.create(request));
// Add first row
List<String> row = [...];
getSheetApi().spreadsheets.values.append(createSheetRows([columns]), sh.spreadsheetId, "Sheet1!$startLetter:$endLetter",
valueInputOption: 'USER_ENTERED');
...
static sheets.ValueRange createSheetRows(List<List<String>> row){
return sheets.ValueRange.fromJson({
"values": row,
"majorDimension": "ROWS"
});
}
static sheets.ValueRange createSheetRow(List<String> row){
return createSheetRows([row]);
}
Cannot convert JSON into Objects
i All,
The Project: A handy utility for tickets at work to help sort and manage my tickets, built on top of our provider's API.
My Background: I'm like 19 hours total into dart and am almost done with my first bootcamp.
The GIST: I have started writing a provider for our helpdesk software's API. I am sending requests to the API successfully but I am utterly clueless on transforming the data into an actual map to generate ticket instances with.
What I'm trying to accomplish:
Fetch the data from the API
Convert that String into a MAP of json objects that I can iterate
through
Iterate through the JSON objects to create instances of ticket
objects with
build a list of those ticket objects and return it to requestor to
generate a widget list.
I could swear I've done everything reasonable to try and type cast this as a map but I think there is something I just don't understand. FWIW I think whatever it is I'm trying to do is accessing a Future not the actual data. and I think i might be confused or unclear about async/awaits but my understanding of the code I've written is that the actions are chained one to another so I shouldn't be "waiting" for anything or getting a future, I should just be getting a string.
Otherwise, Here's my code cleaned up, any advice or suggestions on working with the data in the print would be much appreciated.
class ticketingsoftwareAPIProvider {
// Object Properties
Client _client = Client();
final String _ApiKey = "YOUSHALLPASS!";
final String apiRoot = "https://api.ticketingsoftware.com";
final String agentId = '2675309';
getAgentTickets() async {
// Headers for our HTTP Request
Map<String, String> headers = {
'X-ticketingsoftware-Authorization': 'Bearer $_ApiKey',
'Accept': 'application/vnd.ticketingsoftware.v2.1+json',
'Content-Type': 'application/json'
};
await _client
.get(Uri.parse('$apiRoot/incidents.json?assigned_to=$agentId'))
.then((data) {
if (data.statusCode == 200) {
print(json.decode(data.body));
// CANT SEEM TO MAKE THIS A INTO A MAP TO GENERATE OBJECTS WITH.
}
});
}
}
} // END CLASS
I apologize for any missing information, I am new to dart and REALLY programming in general and am still learning the culture. please let me know if there is any additional information that might help.
My Solution ended up being:
List ticketJson = json.decode(data.body);
for (var ticket = 0; ticket < ticketJson.length; ticket++) {
thisAgentsTickets.add(incident.fromJson(ticketJson[ticket]));
return thisAgentsTickets;
I think I've been learning from a very out of date course.
You need fromJson method to convert it to an object. For example
if (data.statusCode == 200) {
return AgentTicket = AgentTicket.fromJson(data.body)
}
Use json_serializable package for easy way to create the method, or you can create it manually too.
Flutter authentication with email and password without using Firebase
Is it possible to achive authentication with email and password in flutter without using firebase? I have searched around Stackoverflow and internet in general and found nothing about this.
I am creating a simple authentication class this is what I have done at the moment:
class User {
bool isAuthenticated = false;
late String userid;
late String username;
late String email;
late DateTime expireDate; // this variable is used to make the user re-authenticate when today is expireDate
User(bool isAuthenticated, String userid, String username, String email) {
this.isAuthenticated = isAuthenticated;
this.userid = userid;
this.username = username;
this.email = email;
this.expireDate = new DateTime.now().add(new Duration(days: 30));
}
}
class Authentication {
Future<User> signin(String email, String password) {}
void signup(String username, String email, String password) {}
}
EDIT #1: I know how to setup a cookie/token based authentication server I have my own repos on that topic: cookie authentication, token authentication but I don't know how to handle the tokens/cookies in flutter.
This answer is based of #edit1. Since you mentioned that you already know how to set up tokens on the server side you're half way done. Here's a few assumptions I'm making, you already know js/php and worked with JSON output, The database already has a column and table that keeps track of sessions and user_id.
Since you know how Cookies are built this should be relatively easy cause i built it around similar architecture. We has to use the local memory that app's provide access to. There are two packages in flutter that allow u to do this, you can use either:
shared_preferences package link
flutter_secure_storage package link
The main difference is if you want to store 'tokens' or data you want secure you would obviously use flutter_secure_storage. I'm going to use this for code example. And yes the data is saved even after the app is closed.
Setting up Tokens(flutter):
Setting up User Class
When using firebase we generally take for granted the user class that comes with flutter_auth but that is basically what we have to build. A user class with all the data u want to store and then a function called authenticate.
class AppUser{
final _storage = new FlutterSecureStorage();
//below class is mentioned in the next part
AuthApi api = new AuthApi();
//constructor
AppUser(){
//ur data;
};
Future<bool> authenticate(email, password) async {
//this is the api mentioned in next part
http.Response res = await api.login(email, password);
Map<String, dynamic> jsonRes = jsonDecode(res.body);
if (jsonRes["error"]) {
return false;
}
_setToken(jsonRes["token"]);
_setUID(jsonRes["user-id"].toString());
_setAuthState(true);
return true;
}
Future<void> _setToken(String val) async {
//how to write to safe_storage
await _storage.write(key: 'token', value: val);
}
Future<void> _setUID(String val) async {
await _storage.write(key: 'user_id', value: val);
}
//you can stream this or use it in a wrapper to help navigate
Future<bool> isAuthenticated() async {
bool authState = await _getAuthState();
return authState;
}
Future<void> _getAuthState() async {
//how to read from safe_storage u can use the same to read token later just replace 'state' with 'token'
String myState = (await _storage.read(key: 'state')).toString();
//returns boolean true or false
return myState.toLowerCase() == 'true';
}
Future<void> _setAuthState(bool liveAuthState) async {
await _storage.write(key: 'state', value: liveAuthState.toString());
}
}
and assuming ur going to authenticate on a button press so it would look like
onPressed(){
AuthUser user = new AuthUser();
if(user.authenticate(email, password)){
//if logged in. Prolly call Navigator.
}else{
//handle error
}
}
Setting up api calls
Oka so this is calling a Node express API, and the json output looks like
//if successful
{"status":200, "error": false, "token": "sha256token", "user-id": "uid"}
we need to create a class that will give us an output for making this call hence the AuthApi class
class AuthApi {
//this is the login api and it returns the above JSON
Future<http.Response> login(String email, String password){
return http.post(
Uri.parse(ip + '/api/auth/login'),
headers: <String, String>{
'Content-Type': 'application/json',
},
body: jsonEncode(<String, String>{
"email": email,
"password": password,
}),
);
}
}
Thank you for clarifying what u needed, it helped answer better.
You can use Nodejs & express to create your own API and MongoDB or any other DB to act as a persistent DB. I am attaching my github repo link which has minimum code required to setup a email/password auth in mongodb Github EDIT : I have little to no idea about sessions but for tokens there are packages in pub.dev which lets you decode the tokens. jwt-decoder. You can check the expiry time of the token using this package and for storing them you can use secure_storage I had a look at your token authentication repo. I would suggest you to verify the token when you get them and not just blindly trust them.
Yes it is Totally possible to create Authentication without Firebase, but it becomes a-lot more difficult and there are multiple solutions. What firebase provides: Server space with no down time Complete set of Api's including authentication with various methods Strong security(built by google) Ease of use and setup with great documentation The reason I bring these up is cause the alternative ur looking for is very difficult for a programer who's relatively new and can feel like you are building multiple applications at a time. It's definitely a learning curve. Also I'm assuming u don't just want local authentication cause thats kinda pointless. Creating ur own backend involves: Setting up a server(usually ubuntu)(and either on a raspi or a host like amazon, digital ocean, etc) Setting up a database with tables(mysql, sql, mongoDB) Creating communication API's (php, Node.js) So here's what i'd recommend for getting into backend dev, use LAMP architecture : Linux, Apache, MySQL, PHP Setting up Lamp isn't too hard heres a link i followed: https://www.digitalocean.com/community/tutorials/how-to-install-linux-apache-mysql-php-lamp-stack-on-ubuntu-16-04 After u set up ur back end, then u have to create api calls from flutter. The call (if u created an auth.php where people can login) would look something like: http://ip:8080/auth.php?email="example#gmail.com"&pass="123456" I understand why you feel like you didn't find solutions, i was there too but there are tons,LAMP is one of the more easier ones. If u are still interested i'd recommend checking out System Design courses.
Google IAP get subscription details and store in DB
I have an app that receives subscriptions from the user. I have implemented methods to receive payments and I can complete the transaction. When storing all the details in my database I can able to get details such as purchase id, purchase date and validity (returned P1Y for a 1-year subscription) but I also want to get the subscription end date is it possible? and how do I check if the user cancels the subscription or renews the subscription?
Revenue Cat:
Instead of using in_app_purchase I started using purchases_flutter (RevenueCat)
You can refer to their documentation for more information.
I currently use this method for in-app subscriptions.
Google Api:
I also managed to use google API to get the subscription details with the help of googleapis and googleapis_auth
IAP Helper class
Follow this documentation to complete the initial setup
Google API Credentials initialisation
final _credentials = ServiceAccountCredentials.fromJson(r'''
{
"private_key_id": "keyid",
"private_key": "-----BEGIN PRIVATE KEY-----\nMIIEvgIBADAN<private key>Sf\nbB9OjCOGt7ybJmDkMBe2U5Tq\n-----END PRIVATE KEY-----\n",
"client_email": "mail",
"client_id": "clientid",
"type": "service_account"
}
''');
static const _scopes = [AndroidPublisherApi.androidpublisherScope];
Function to get Subscription details
Future getSubData({#required String token , #required String productId})async{
SubscriptionPurchase res;
final httpClient = await clientViaServiceAccount(_credentials, _scopes);
try {
final pubApi = AndroidPublisherApi(httpClient);
res = await pubApi.purchases.subscriptions.get('com.yourcompany.package', productId, token);
} finally {
httpClient.close();
}
return res;
}
Delivering the product
_deliverProduct({#required PurchaseDetails purchaseDetails})async{
await iap.completePurchase(purchaseDetails);
final firestore.DocumentReference userDocReference = firebase.doc("Users/$_id/userdata/data");
final firestore.CollectionReference historyDocReference = firebase.collection("Users/$_id/history/");
final SubscriptionPurchase apiRes = await getSubData(token:purchaseDetails.billingClientPurchase.purchaseToken,productId:purchaseDetails.productID);
var data = {
"TXN ID": purchaseDetails.billingClientPurchase.purchaseToken,
"Order ID":purchaseDetails.billingClientPurchase.orderId,
"Product ID":purchaseDetails.productID,
"TXN Date": firestore.Timestamp.fromMillisecondsSinceEpoch(int.parse(purchaseDetails.transactionDate)),
"Subscribed":true,
"Start Date":firestore.Timestamp.fromMillisecondsSinceEpoch(int.parse(apiRes.startTimeMillis)),
"Expiry Date": firestore.Timestamp.fromMillisecondsSinceEpoch(int.parse(apiRes.expiryTimeMillis)),
"Payment Status": apiRes.paymentState,
"isFreeTrail": (apiRes.paymentState==1)?false:true,
"acknowledgementState":apiRes.acknowledgementState
};
await userDocReference.set({"Subscription":data,"Sub_Raw":apiRes.toJson()},firestore.SetOptions(merge: true)); //set to main user
await historyDocReference.doc('${purchaseDetails.billingClientPurchase.purchaseToken}').set(data); //put in purchase history
}
Now you can check if the user is subscribed or not from your firstore BD
This method may provide temporary FIX (Google PlayStore only) but I do not recommend this method as it contains a lot of security issues.
Note: Google only provides 200K API call's per day avoid calling API to check for subscription repeatedly.
Note: Google API method only works with in_app_purchase: ^0.5.2
Note: Google API method only works for Android and doesn't work for IOS.
Other Alternates
You can write your own server-side code in node.js/cloud firestore and you can achieve the same.
Ref : Cook book in_app_purchase
Disclaimer
I do not receive any incentive/payment from revenuecat for mentioning their product in this answer.