Calling a smart contract function (JS, NodeJS)

by Delbypoc

This tutorial is for educational purposes only, I’m not responsible for any losses, damages, or other liabilities which may occur by using any info/code provided here(or anywhere else it is posted).

I’m under no circumstances a Javascript professional (or a JS Ninja/Expert)!

The code is not production-ready! (only for learning purposes)

In this guide, I’m going to show you how to call a smart contract function on MATRIX AI NETWORK.

This is a continuation of the last guide:

https://medium.com/@delbypoc/deploying-a-smart-contract-on-matrix-ai-network-using-truffle-demo-part-1-cff8714add2

We will make use of the following packages : ‘aiman’, ‘matrixjs-tx’, ‘bignumber.js’, ‘bs58’, ‘fs’.

You can install them by using :

npm install aiman matrixjs-tx bignumber.js bs58 fs

and declare them:

For testing, I will use the smart contract from the last guide:

It contains one function that changes the result value and a view function.

After running Truffle migrate (from the last guide), some files will also get generated under the build/contracts folder, SimpleContract.json

I will read it using fs (it will be required to get the contract ABI)

Now I will initialize the man3 instance with a provider:

And other variables that will be used in building the tx:

Next, I will declare and implement a function that will prepare the tx and broadcast it:

The program should output the tx that got broadcasted (blurred out a few details):

After solving the promise (and tx get mined), we should have the “result” variable of the smart contract changed to 220.

We can also check the input parameters by decoding the transaction “input” (I will use https://lab.miguelmota.com/ethereum-input-data-decoder/example/ for this)

The whole program source code can be found at the github page: (Matrix-AI-Network-Code-Snippets/callingSmartContractFunction.js at main · CognitiveProcessing/Matrix-AI-Network-Code-Snippets (github.com))

For more documentation on the packages used, you can check: https://www.npmjs.com/package/bignumber.js

https://www.npmjs.com/package/buffer

https://www.npmjs.com/package/bs58

https://www.npmjs.com/package/fs

Also, check out the official Matrix AI Network Developer Portal: dev.matrix.io