---
title: Read Contracts State
slug: signum/read-contracts-state
createdAt: 2022-09-08T12:10:04.000Z
---

As explained in [Smart Contracts](docId\:SmT0kwoLdxbPwgBU1I1ht), the data stack has a fixed layout and can be read in 8-byte blocks. The following example shows how to read parts of a [NFTSRC40](https://github.com/signum-network/SIPs/blob/master/SIP/sip-40.md) contract, which are deployed through the [Signum NFT platform](https://signumart.io)

This full example in the [SignumJS examples folder](https://github.com/signum-network/signumjs/blob/main/examples/nodejs/advanced/contracts/viewContractData.js)



```javascript
const {Address} = require("@signumjs/core");
const {ContractDataView} = require("@signumjs/contracts");
const {Amount} = require("@signumjs/util");

/**
 * This is an example of how to read data from a contract
 *
 * Usually, contracts maintain a certain internal state, like ownership, paid dividends or whatever
 * These data is publicly accessible and can be read relatively easily using ContractDataView
 * The requirement is that you know the positions of the values in the contracts data stack.
 * The data stack is divided into 8 byte segments and can be addressed using indices.
 *
 * The following example uses parts of the layout of the NFTSRC40 contract.
 *
 * If you use your custom contracts, you might want to use the Contract Inspector to see you data stack
 *
 * https://contracts-inspector.ohager.vercel.app/
 *
 */
const NftContractDataIndex = {
    Owner: 0,
    Status: 1,
    CurrentPrice: 2,
    PlatformAddress: 3,
    PlatformFee: 4,
    RoyaltiesFee: 5,
    RoyaltiesOwner: 6,
    HighestBidder: 19,
    TotalTimesSold: 27,
    TotalBidsReceived: 28,
    TotalRoyaltiesFee: 29,
    TotalPlatformFee: 30,
    TotalLikes: 31,
}

// using a dedicated class for contract data view is a good practice
class NftDataView {
    constructor(contract) {
        this.id = contract.at;
        // ContractDataView gives us easy access to the 8-byte blocks
        this.view = new ContractDataView(contract);
    }

    getId() {
        return this.id;
    }

    getOwnerId() {
        return this.view.getVariableAsDecimal(NftContractDataIndex.Owner);
    }

    getRoyaltiesOwnerId() {
        return this.view.getVariableAsDecimal(NftContractDataIndex.RoyaltiesOwner);
    }

    getPlatformId() {
        return this.view.getVariableAsDecimal(NftContractDataIndex.PlatformAddress);
    }

    getPlatformFee() {
        return parseInt(
            this.view.getVariableAsDecimal(NftContractDataIndex.PlatformFee),
            10
        );
    }

    /* ... and so on, and so forth */
}


const LedgerHostUrls = {
    TestNet: 'http://localhost:6876',
    MainNet: 'https://europe.signum.network',
}


function asAddress(id, prefix){
    return Address.fromNumericId(id, prefix).getReedSolomonAddress()
}

/**
 * This advanced example shows how to interact with smart contracts, i.e. how to call methods
 */
async function showNftData({ledgerChoice, nft}) {
    try {
        const ledger = LedgerClientFactory.create({
            nodeHost: LedgerHostUrls[ledgerType])
        }

        // this way we not only convert the contracts address to its id, but this method also asserts
        // that we have a formally valid address. It's not guaranteed that the address really exists in the chain
        const nftId = Address.create(nft).getNumericId()

        const nftContract = await ledger.contract.getContract(nftId)
        const explorerUrl = ledgerChoice === 'TestNet' ? `https://t-chain.signum.network/at/${nftId}` : `https://chain.signum.network/at/${nftId}`
        const prefix = ledgerChoice === 'TestNet'? 'TS' : 'S'
        const nftDataView = new NftDataView(nftContract)

        console.info(`Stats of NFT '${asAddress(nftId, prefix)}' - ${explorerUrl}`)
        console.info('----------------------------------------')
        console.info('Creator:', nftContract.creatorRS)
        console.info('Current Owner:', asAddress(nftDataView.getOwnerId(),prefix))
        console.info('Current Price:', nftDataView.getCurrentPrice().getSigna(), 'SIGNA')
        console.info('Current Status:', nftDataView.getStatus())
        console.info('Number of Sales:', nftDataView.getTotalTimesSold())
        console.info('Likes:', nftDataView.getTotalLikes())
    } catch (e) {
        console.error(e);
    }
}

(async () => {
    await showNftData({
        ledgerChoice: 'TestNet',
        nft: '5704341721881819656'
    });
})();

```