I am trying to return a matrix in React that I get from a contract function.

This is the function that resonate the matrix:

    int[][] public publicData;

    function handleAddData(int[] memory data) public {



   function getData() public returns(int[][] memory data) {
    return publicData;

I'm using solidity version 0.5.

In React, I try to get the data as follows from the app.js file:

import React, {Component} from 'react';
import logo from './logo.svg';
import './App.css';
import web3 from './web3';
import datastorage from './datastorage';

class App extends Component {

  state = {
    data: []

  async componentDidMount() {
    const data = await datastorage.methods.getData().call();
    this.setState({ data });

  render() {

    return (
        <h2>Data: </h2>
        <p>Aqui: {this.state.data}</p>


export default App;

If i use {this.state.data.length} it returns me the size, but when I try to get the data inside the matrix, I can't.

1 Answer 1


Add the following functions in your contract, an then use them in your application:

function getLength() public view returns (uint) {
    return publicData.length;

function getDataLength(uint index) public view returns (uint) {
    return publicData[index].length;

Usage example:

const length = await datastorage.methods.getLength();
for (let i = 0; i < length; i++) {
    const dataLength = await datastorage.methods.getDataLength(i);
    for (let j = 0; j < dataLength; j++) {
        const item = await datastorage.methods.publicData(i, j);
        console.log(`publicData[${i}][${j}] = ${item}`);

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