Truffle contract Interaction-reading and writing of Ethernet square data on the web end of the ether square

1. Initialization of truffle

Truffle init Webpack

1 2

can refer to: here 2. Write a contract

Here is a simple contract.

pragma solidity ^0.4.2;

Contract Credit {

  event CreateRecord (address indexed _address, string identity, uint category, uint price);

  string A;
  UINT B;
  UINT C;

    function Create (string identity, uint category, uint256 price)
  {
      a = identity;
      b = category;
      c = Price;
      CreateRecord (Msg.sender, identity, category, price);
  }

  function All () returns (strings, uint, uint) {return
      (A, B, c);
  }

}

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23-24 3. Deployment Contract

Mentioned in the previous article: here 4. To modify an HTML file

This assumes that you already have a web base.

Write 3 input, namely identity, classification and price. Notice the IDs of them

and 2 buttons: Commit: Will call the Savemessage function and write the data to the ether. Get information: Call the GetMessage function, read the data from the Ethernet square

<! DOCTYPE html> 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28-29
5. Modify the App.js file 
Note the introduction of the file.

Import the page ' s CSS.
Webpack'll know what to does with it. Import "..

/stylesheets/app.css ";
Import Libraries we need.
Import {default as Web3} from ' web3 '; Import {default as Contract} from ' Truffle-contract '//Import we contract artifacts and turn them into usable abstrac
tions. Import credit_artifacts from '. /..
/build/contracts/credit.json '//Metacoin are our usable abstraction, which we'll use through the code below.

var credit = contract (credit_artifacts);
Show the interaction with the contract var accounts;

var account; Window.

    APP = {start:function () {var self = this;
    Bootstrap the credit abstraction for use.

    Credit.setprovider (Web3.currentprovider); Gets the initial account web3.eth.getAccounts (function (err, ACCS) {if (err!= null) {alert ("There was" error Fetchin
        G your accounts. ");
      Return } if (accs.length = = 0) {alert ("couldn ' t get any accounts!
        Make sure your Ethereum the client is configured correctly. ");
      Return} accounts = ACCs;
    account = Accounts[0];
    Self.refreshbalance ();
  });
    //Set page text information setstatus:function (message) {var status = document.getElementById ("status");
  status.innerhtml = message;
    //Get information from ether Getmessage:function () {var self = this;

    var meta;

    var a,b,c;
        Credit.deployed (). Then (function (instance) {meta = instance;
    Return Meta.all.call ({from:account});
    }). Then (function (value) {self.setstatus (value);
      ). catch (function (e) {Console.log (e)); Self.setstatus ("Error getting message.")
      See log. ");},//write data to Etheric square savemessage:function () {var self = this;

      var meta;
      var identity = document.getElementById ("Identity"). Value;
      var category = parseint (document.getElementById ("category"). value);

      var price = parseint (document.getElementById ("price"). Value);
         Credit.deployed (). Then (function (instance) {meta = instance; Return Meta.create (identity, category, price, {from:account});
      }). Then (function () {self.setstatus (identity);
        ). catch (function (e) {Console.log (e));
    Self.setstatus ("Error");
  });

}
}; The following paragraph should be done without the control of copying. Web page load is invoked.
But in fact I don't understand, to be solved. Window.addeventlistener (' Load ', function () {if (typeof web3!== ' undefined ') {Console.warn ("Using web3 detected F Rom external source. If you find this your accounts don ' t appear or you have 0 metacoin, ensure your ' ve configured that source properly. If using Metamask, the following link. Feel free to delete this warning. :) Http://truffleframework.com/tutorials/truffle-and-metamask ")//Use Mist/metamask ' s provider window.web3 = new
  WEB3 (Web3.currentprovider); else {Console.warn ("No web3 detected. Falling back to http://localhost:8545. You are should remove this fallback if you are deploy live, as it's inherently insecure. Consider switching to metamask for development. More info here:http://trUffleframework.com/tutorials/truffle-and-metamask "); Fallback-use your fallback strategy (local node/hosted node + in-dapp ID mgmt/fail) window.web3 = new Web3 (NE
  W Web3.providers.HttpProvider ("http://localhost:8545"));
} app.start (); });
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