I'm completely new to both blockchain and JavaScript.
I'm trying to create a simple web page where people could generate a "wedding" smart contract that basically store their 2 names. For this I have created a WeddingCerficate contract which store the names and have a getter function, and a WeddingCertificateFactory That enable me to generate a WeddingCertificate. You can find the code of the smart contracts in solidity below.
// SPDX-License-Identifier: MIT
pragma solidity >=0.7.0 <0.9.0;
contract WeddingCertificate{
string private spouse1;
string private spouse2;
constructor(string memory _spouse1, string memory _spouse2) {
spouse1 = _spouse1;
spouse2 = _spouse2;
}
function getSpouses() public view returns (string memory,string memory) {
return (spouse1,spouse2);
}
}
contract WeddingCertificateFactory{
event Wedding(string _spouse1, string _spouse2, address indexed contract_adress );
function Unite(string memory _spouse1, string memory _spouse2)public returns (bool success) {
WeddingCertificate wedding = new WeddingCertificate(_spouse1, _spouse2);
emit Wedding(_spouse1,_spouse2 , address(wedding));
return true ;
}
}
I deployed the WeddingCertificateFactory on Goerli Tesnet. And now I'm trying to make a function in javascript (using ether.js) to enable a user to create his own weddingCertificate directly on a web interface.
For this I wrote the function below but for some reasons this only generates the new Wedding certificate once out 20. And even when it actually work, the two last print aren't visible in the console.
I do not get any error (at least that I can see in the console) when I test the function and nothing happen.
I'm not familiar with async in JavaScript, I also tried the .then( syntax but I didn't notice any difference.
async function CreateWedding(){
const spouse1 = document.getElementById("spouse1").value;
const spouse2 = document.getElementById("spouse2").value;
if (spouse1.length > 0 && spouse2.length >0) {
console.log(`spouse 1: ${spouse1} , spouse2 : ${spouse2} `);
const ethereum = window.ethereum ;
const accounts = await ethereum.request({
method: "eth_requestAccounts",
});
const provider = new ethers.providers.Web3Provider(ethereum, "any");
const walletAddress = accounts[0];
const signer = provider.getSigner(walletAddress);
let abi = [
" function Unite(string memory _spouse1, string memory _spouse2)"
];
const contractAddress = "0x2556Ff7f7F1c013bBB60bD120E1828032Cd84cc4"; //WeddingFactory Contract
const contract = new ethers.Contract(contractAddress, abi, signer);
console.log("sending the contract");
tx = await contract.Unite(spouse1,spouse2);
console.log(tx);
console.log("finished");
} else {
alert("Please enter 2 names");
}
}
Try creating your abi method in web3client.app.
It has code generater for ether.js which yoy can use directly in your app.
If there is an actual issue in your contract it would fail there itself.
I am trying to use the v3 CAF receiver app using DRM to casting videos, from my IOS app. If I use the basic v3 CAF receiver app (default receiver) it is working fine, but when I using DRM url (dash/.mpd and licenseUrl ) it will throw below error
Error
[ 20.844s] [Error] [INFO] {"type":"LOAD_CANCELLED","requestId":0}
See the below code.
const playerManager = context.getPlayerManager();
const playbackConfig = new cast.framework.PlaybackConfig();
/** Debug Logger **/
const castDebugLogger = cast.debug.CastDebugLogger.getInstance();
var manifestUri = 'https://example.domain.video/prod/drm/1/7e942940-d705-4417-b552-796e8fd25460/Media_1_20_d2aaec7102dc42c09dd54e4f00cbea412019062801270383196000/dash/manifest.mpd';
var licenseServer = 'https://wv.example.domain.com/hms/wv/rights/?ExpressPlayToken=BQALuGDeKZcAJDE2YzAwYTRkLTYwZWYtNGJiZC1hZmEzLTdhMmZhYTY2NzM5OQAAAHCZzHVjRyfs3AEgxFuwPvZsrqMndjiBPzLQ5_VUx6rJOEDD5noQmXJoVP-Va1gQzxfp9eHux15_pEr6g0RxXNZIjlsN6b7SIfpHPyS9iuPQqgvEgq5I_tV9k1lhQvKuqgpBN0Z5BtxCLwHc8xrnLbuUK6fiThcLMR4He_x38reAsumjFYg';
// setting manually licenseUrl from here
playbackConfig.licenseUrl = licenseServer;
playbackConfig.manifestRequestHandler = requestInfo => {
requestInfo.withCredentials = true;
};
playbackConfig.licenseRequestHandler = requestInfo => {
requestInfo.withCredentials = true;
requestInfo.headers = {
// 'Content-type':'application/dash+xml', // trying this also
'Content-type':'application/octet-stream'
}
playbackConfig.licenseUrl = requestInfo.media.customData.licenseUrl;
return playbackConfig;
};
// MessageInterceptor
playerManager.setMessageInterceptor(
cast.framework.messages.MessageType.LOAD,
request => {
const error = new cast.framework.messages.ErrorData(cast.framework.messages.ErrorType.LOAD_CANCELLED);
castDebugLogger.info('Error', error);
if (!request.media) {
error.reason = cast.framework.messages.ErrorReason.INVALID_PARAM;
castDebugLogger.info('reason', error.reason);
return error;
}
if (request.media && request.media.entity) {
request.media.contentId = request.media.entity;
}
return new Promise((resolve, reject) => {
if (!request.media) {
castDebugLogger.error('MyAPP.LOG', 'Content not found');
reject();
} else {
// I have passed manually data (license Url and content Id etc.) from here for testing purpose
const item = new cast.framework.messages.QueueItem();
item.media = new cast.framework.messages.MediaInformation();
item.media.contentId = manifestUri;
item.media.streamType = cast.framework.messages.StreamType.BUFFERED;
// Trying all options of contentType
item.media.contentType = "application/octet-stream";
//request.media.contentType = 'application/x-mpegurl';
//item.media.contentType = "video/mp4";
//request.media.contentType = 'video/mp4';
//request.media.contentType = 'application/dash+xml';
item.media.metadata = new cast.framework.messages.MovieMediaMetadata();
item.media.metadata.title = "Example title";
item.media.metadata.subtitle = "Example subtitle ";
item.media.metadata.images = [new cast.framework.messages.Image("https://commondatastorage.googleapis.com/gtv-videos-bucket/sample/images/BigBuckBunny.jpg")];
request.media = item.media;
playbackConfig.protectionSystem = cast.framework.ContentProtection.WIDEVINE;
resolve(request);
}
});
});
// start
context.start({
playbackConfig: playbackConfig,
touchScreenOptimizedApp: true
});
LA_URL and .mpd url is working fine with another online shaka player.
Did you check in the remote web inspector if the network request is sent to the licenser when the load request is issued for the encoded dash stream? Most probably this will help to find where the problem is.
Possibly you will have to add some inteligence to your licenseRequestHandler to add a token of some sort. Or possibly there's a CORS issue.
Note: Before you post some code to stackoverflow, it might be wize to clean it up a bit: remove dead code, remove confusing commented code, provide proper indentation. You're wasting brain cycles of everybody reading your code and trying to process what you shared with the world!
I was watching the tutorial on Youtube and following the instruction:
https://www.youtube.com/watch?time_continue=1350&v=msT3tpwnyv8
When I try to call the function with the js file below, it returned nothing on the console. Does anyone know what happened?
I am using,
web3.js 1.0.0 beta. 52
infura to connect
var Tx = require('ethereumjs-tx')
const Web3 = require('web3');
const web3 = new Web3('https://ropsten.infura.io/v3/project_id')
const contractAddress = '0xd03696B53924972b9903eB17Ac5033928Be7D3Bc'
const contractABI = [{"constant":true,"inputs":[],"name":"name","outputs":[{"name":"","type":"string"}],"payable":false,"stateMutability":"view","type":"function"},{"constant":false,"inputs":[{"name":"_spender","type":"address"},{"name":"_value","type":"uint256"}],"name":"approve","outputs":[{"name":"success","type":"bool"}],"payable":false,"stateMutability":"nonpayable","type":"function"},{"constant":true,"inputs":[],"name":"totalSupply","outputs":[{"name":"","type":"uint256"}],"payable":false,"stateMutability":"view","type":"function"},{"constant":false,"inputs":[{"name":"_from","type":"address"},{"name":"_to","type":"address"},{"name":"_value","type":"uint256"}],"name":"transferFrom","outputs":[{"name":"success","type":"bool"}],"payable":false,"stateMutability":"nonpayable","type":"function"},{"constant":true,"inputs":[],"name":"standard","outputs":[{"name":"","type":"string"}],"payable":false,"stateMutability":"view","type":"function"},{"constant":true,"inputs":[{"name":"","type":"address"}],"name":"balanceOf","outputs":[{"name":"","type":"uint256"}],"payable":false,"stateMutability":"view","type":"function"},{"constant":true,"inputs":[],"name":"symbol","outputs":[{"name":"","type":"string"}],"payable":false,"stateMutability":"view","type":"function"},{"constant":false,"inputs":[{"name":"_to","type":"address"},{"name":"_value","type":"uint256"}],"name":"transfer","outputs":[{"name":"success","type":"bool"}],"payable":false,"stateMutability":"nonpayable","type":"function"},{"constant":true,"inputs":[{"name":"","type":"address"},{"name":"","type":"address"}],"name":"allowance","outputs":[{"name":"","type":"uint256"}],"payable":false,"stateMutability":"view","type":"function"},{"inputs":[],"payable":false,"stateMutability":"nonpayable","type":"constructor"},{"anonymous":false,"inputs":[{"indexed":true,"name":"_from","type":"address"},{"indexed":true,"name":"_to","type":"address"},{"indexed":false,"name":"_value","type":"uint256"}],"name":"Transfer","type":"event"},{"anonymous":false,"inputs":[{"indexed":true,"name":"_owner","type":"address"},{"indexed":true,"name":"_spender","type":"address"},{"indexed":false,"name":"_value","type":"uint256"}],"name":"Approval","type":"event"}]
var contract = new web3.eth.Contract(contractABI, contractAddress)
contract.methods.totalSupply().call((err, result)=> {
console.log(result)
})
Try:
contract.methods.totalSupply().call().then((result) => {console.log(result) });
It should return a BigNumber.
I have successfully compiled and published my contract in the rinkeby testnet with the remix browser compiler. Now I am struggling to call a function of my contract, either because my code is wrong or because it's published on rinkeby?
Can someone please provide me an example how to call this function using javascript and/or directly from the remix compiler:
function balanceOfTestCoin() returns (uint amount){
for (uint i = 0; i < funders.length; i++){
if(funders[i].addr == msg.sender){
return funders[i].amountTestCoin;
}
}
return 0;
}
Right now i am trying it this way:
<script>
if (typeof web3 !== 'undefined') {
window.web3 = new Web3(web3.currentProvider);
} else {
console.log('No web3? You should consider trying MetaMask!')
}
web3.eth.defaultAccount = web3.eth.accounts[0];
var abi = [{...}];
var MyContract = web3.eth.contract(abi);
var myContractInstance = MyContract.at('0x....');
console.log(myContractInstance);
myContractInstance.balanceOfTestCoin(function(amount){ alert(amount) });
//This doesnt work aswell:
alert("My TestCoins: " + myContractInstance.balanceOfTestCoin());
</script>
I am getting invalid address error on the line where I am trying to call the function. I am very thankful for any kind of help.
function FriendlyChat() {
// statements
}
FriendlyChat.protoype.somemethod = function() {
// statements
};
FriendlyChat.protoype.somemethod2 = function() {
//statements
};
window.onload = function() {
window.friendlyChat = new FriendlyChat();
};
So i noticed the above structure for js while working on a google codelab.
And I have two ques.
in normal objects you have to call the function i.e Object.somemethod()
How does this structure call the methods assigned to it.
From my limited understanding, Firendlychat.protoype.the method treats the
function as an object and the methods are passed to the new object created on
window.onload.Via
inheritance, The object created i.e friendlychat has all these methods.
Yet none of the methods are called in any way. How does this work?
Is there any advantage to structuring your code in this way other than
readability
Note :
Main function
function FriendlyChat() {
this.checkSetup();
// Shortcuts to DOM Elements.
this.messageList = document.getElementById('messages');
this.messageForm = document.getElementById('message-form');
// Saves message on form submit.
this.messageForm.addEventListener('submit', this.saveMessage.bind(this));
this.signOutButton.addEventListener('click', this.signOut.bind(this));
this.signInButton.addEventListener('click', this.signIn.bind(this));
// Toggle for the button.
var buttonTogglingHandler = this.toggleButton.bind(this);
this.messageInput.addEventListener('keyup', buttonTogglingHandler);
this.messageInput.addEventListener('change', buttonTogglingHandler);
// Events for image upload.
this.submitImageButton.addEventListener('click', function(e) {
e.preventDefault();
this.mediaCapture.click();
}.bind(this));
this.mediaCapture.addEventListener('change',
this.saveImageMessage.bind(this));
this.initFirebase();
}
//the methods are setup here
// Sets up shortcuts to Firebase features and initiate firebase auth.
FriendlyChat.prototype.initFirebase = function() {
this.auth = firebase.auth();
this.database = firebase.database();
this.storage = firebase.storage();
// Initiates Firebase auth and listen to auth state changes.
this.auth.onAuthStateChanged(this.onAuthStateChanged.bind(this));
};
// Saves a new message on the Firebase DB.
FriendlyChat.prototype.saveMessage = function(e) {
e.preventDefault();
}
};
FriendlyChat.prototype.setImageUrl = function(imageUri, imgElement) {
imgElement.src = imageUri;
};
// Saves a new message containing an image URI in Firebase.
// This first saves the image in Firebase storage.
FriendlyChat.prototype.saveImageMessage = function(event) {
event.preventDefault();
var file = event.target.files[0];
// Clear the selection in the file picker input.
this.imageForm.reset();
// Check if the file is an image.
if (!file.type.match('image.*')) {
var data = {
message: 'You can only share images',
timeout: 2000
};
this.signInSnackbar.MaterialSnackbar.showSnackbar(data);
return;
}
// Check if the user is signed-in
if (this.checkSignedInWithMessage()) {
// TODO(DEVELOPER): Upload image to Firebase storage and add message.
}
};
// Signs-in Friendly Chat.
FriendlyChat.prototype.signIn = function() {
var provider = new firebase.auth.GoogleAuthProvider();
this.auth.signInWithRedirect(provider);
};
// Signs-out of Friendly Chat.
FriendlyChat.prototype.signOut = function() {
this.auth.signOut();
};
One of the advantages I've seen when using prototype inheritance was that you can control all instances of an object. For ex:
function FriendlyChat() {
this.chatIsActive = true;
}
FriendlyChat.prototype.deactivateChat = function(...rooms) {
for (chatRoom of rooms) {
chatRoom.chatIsActive = false;
}
};
var chat1 = new FriendlyChat();
var chat2 = new FriendlyChat();
var chatController = new FriendlyChat();
chatController.deactivateChat(chat1, chat2)
console.log(chat1.chatIsActive)
In ES6, however, you can do it:
class FriendlyChat {
constructor() {
this.chatIsActive = true;
}
static deactivateChat(...rooms) {
for (let chatRoom of rooms) {
chatRoom.chatIsActive = false;
}
}
}
var chat1 = new FriendlyChat();
var chat2 = new FriendlyChat();
FriendlyChat.deactivateChat(chat1, chat2)
console.log(chat1.chatIsActive)
And the another advantage of using prototype is that you can save memory spaces when you make an object from new keyword. For instance, the code in ES5 above, you can see chat1 and chat2 I've made by using new. Then chat1 and chat2 will be able to access deactivateChat() method which is in a sharing-space. It's because of the concept, called prototype-chaining.
And the next ES6 version is just a syntactic sugar - under the hood it does the same as ES5 version
I post this as a reference to others who have been faced with this dilemma.
First of all, ONe of the core issues for me was migrating from java, I seemed to be familiar territory but things work a bit different in js.I strongly recommend these links:
Objects in Detail
js Prototype
So the key to why this method works is due to the
window.friendlyapp =new friendlychat()
Now normally in most languages you have an object
obj() {
attr : value
method: function() {}
}
And then to use the method you do
var child = new obj();
child.method();
but in this method the var is made an instance of the window object and thats why none of the methods of the app need to be explicitly called.