How to programmatically get current unbonding information on the Polkadot relay chain?

Question

Using either a Rust or JavaScript client library I would like to get the amount of DOT that is currently being unbonded on the relay chain.

Some staking information is available in the Polkadot JS interface:

But it does not include any information about the amount of DOT that is being unstaked (i.e. DOT that is currently in the 28 day unbonding period).

Answer 1

Here's an example of how I managed to get this information using the @polkadot JavaScript libraries.

1. Import the Polkadot JS libraries

yarn add @polkadot/api @polkadot/util

var { ApiPromise, WsProvider } = require('@polkadot/api');
var util = require('@polkadot/util');

2. Initialize the WebSocket provider

Here we use the publicly provided WebSocket RPC endpoint from polkadot.io (wss://rpc.polkadot.io).

const provider = new WsProvider("wss://rpc.polkadot.io", false);
provider.connect();
const api = await ApiPromise.create({ provider });
// ...
provider.disconnect()

3. Get staking/unlocking information starting from current era

// ...
let currentEra = await api.query.staking.currentEra()
let storageKey = ''
let total = util.BN_ZERO

while (true) {
    let stakingEntries = await api.query.staking.ledger.entriesPaged({ args: [], pageSize: 100, startKey: storageKey })

    if (stakingEntries.length == 0) {
        break
    }

    for (entry of stakingEntries) {
        storageKey = entry[0]
        for (item of entry[1].unwrap().unlocking) {
            if (item.era.toNumber() >= currentEra) {
                total = total.add(item.value.toBn())
            }
        }
    }
}

The full program looks like this:

var { ApiPromise, WsProvider } = require('@polkadot/api')
var util = require('@polkadot/util')

async function main() {
    const provider = new WsProvider('wss://rpc.polkadot.io', false)
    provider.connect()
    const api = await ApiPromise.create({ provider })

    let currentEra = await api.query.staking.currentEra()
    let storageKey = ''
    let total = util.BN_ZERO

    while (true) {
        let stakingEntries = await api.query.staking.ledger.entriesPaged({ args: [], pageSize: 100, startKey: storageKey })

        if (stakingEntries.length == 0) {
            break
        }

        for (entry of stakingEntries) {
            storageKey = entry[0]
            for (item of entry[1].unwrap().unlocking) {
                if (item.era.toNumber() >= currentEra) {
                    total = total.add(item.value.toBn())
                }
            }
        }
        console.log('Processed entries:', stakingEntries.length)
        console.log('Storage key:', storageKey.toString())
    }

    console.log('From era:', currentEra.toString())
    console.log('Total unstaking:', total.toString().substring(0, total.toString().length-10), 'DOT')

    provider.disconnect()
}

main().catch(console.error).finally(() => process.exit())

The final output looks like this:

From era: 658
Total unstaking: 33881435 DOT