## Sidecar example for `DED` balance of an account

### Installation Steps
- `git clone https://github.com/paritytech/substrate-api-sidecar.git`
- `cd substrate-api-sidecar`
- `yarn`
- `yarn build`

#### Add .env file
Create a new `.env` file in the root directory that will tell Sidecar to connect to the chain you want through a public endpoint, e.g. Polkadot Asset Hub, instead of your local node.

#### Steps
- `touch .env.polkadotassethub` in the root directory
- and then edit the file and
- add this line `SAS_SUBSTRATE_URL=wss://statemint-rpc.dwellir.com`
- Save the changes

This will connect Sidecar to the public endpoint that is provided by dwellir and it is an example. You can find other public endpoints from other providers.

**IMPORTANT NOTE:** It is worth mentioning that in production environment we do not recommend using public endpoints but a full local node that you maintain.

For the installation you need to have nodejs installed which I assume you already do.

### Run Sidecar
Last you can start Sidecar by running the command
- `NODE_ENV=polkadotassethub yarn start` in the root dir

assuming that you named your `.env` file as mentioned previously.

#### Sidecar Endpoints
Now if you open any browser and give this address http://127.0.0.1:8080/ you will see all the endpoints that are available to you.

#### Example Endpoint
Check the asset balances of an account, e.g.
`http://127.0.0.1:8080/accounts/155HWw3J9jyYphMm5is4vp9Bzj7ZRRd6HEzCPdWd8cq97KfT/asset-balances`

### Example script
An example script to access the same endpoint can be done as follows:

While your sidecar instance is running you open another terminal :
- `mkdir demo-script`
- `cd demo-script`
- `touch index.js`
- if you edit the `index.js` file you can paste this simple script

const axios = require('axios');

const BASE_URL = 'http://127.0.0.1:8080';

const main = async () => {
    const exampleAccount = '155HWw3J9jyYphMm5is4vp9Bzj7ZRRd6HEzCPdWd8cq97KfT';
    const endpoint = `${BASE_URL}` + '/accounts/' + exampleAccount + '/asset-balances';
    const response = await axios.get(endpoint, { params: { assets: [30] } });
    console.log(response.data);
};

main();

- save the changes
- to run this script you can install `axios` with `npm install axios`
- and then `node index.js`

#### Output
- The result will be the `DED` (since `assetId` of DED is `30`) balance for this example account

{
  at: {
    hash: '0x98e3a9f5f087005c296cd17c0c1709f2fa6d04b80a3369c38c244cb87140a0ad',
    height: '6045104'
  },
  assets: [
    {
      assetId: '30',
      balance: '15646078874736',
      isFrozen: 'isFrozen does not exist for this runtime',
      isSufficient: false
    }
  ]
}

## Asset-Transfer-API example for `DED` transfer

### Installation Steps
Installation steps mentioned in the demo of asset-transfer-api in this [deep dive](https://youtu.be/H6BMBthmwTI?feature=shared) (at the 27 minute mark)

#### Steps
- `mkdir ata-demo`
- `cd ata-demo`
- `npm init -y`
- `npm install @substrate/asset-transfer-api`

### Create DED transfer script
`DED` is available only in Polkadot Asset Hub based on the info we have in the [registry](https://github.com/paritytech/asset-transfer-api-registry/blob/main/docs/registry.json). Thus, it would be a local transaction from one account in Polkadot Asset Hub to another account again in Polkadot Asset Hub. So the code will be very similar to the one shown in this [example](https://github.com/paritytech/asset-transfer-api/blob/main/examples/localParachainTx.ts) but with some slight changes.

- while in `ata-demo` directory
- `touch index.js`
- Open the `index.js` file

const {AssetTransferApi, constructApiPromise} = require('@substrate/asset-transfer-api');

const main = async () => {
	const { api, specName, safeXcmVersion } = await constructApiPromise('wss://statemint-rpc.dwellir.com');
	const assetApi = new AssetTransferApi(api, specName, safeXcmVersion);

	try {
		callInfo = await assetApi.createTransferTransaction(
			'1000',
			'0xF977814e90dA44bFA03b6295A0616a897441aceC',
			['30'],
			['100000'],
			{
				format: 'call',
				keepAlive: true,
			},
		);

		console.log(`The following call data that is returned:\n${JSON.stringify(callInfo, null, 4)}`);
	} catch (e) {
		console.error(e);
		throw Error(e);
	}

	const decoded = assetApi.decodeExtrinsic(callInfo.tx, 'call');
	console.log(`\nThe following decoded tx:\n ${JSON.stringify(JSON.parse(decoded), null, 4)}`);
};

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

#### Output

The following call data that is returned:
{
    "origin": "statemint",
    "dest": "statemint",
    "direction": "local",
    "xcmVersion": null,
    "method": "assets::transferKeepAlive",
    "format": "call",
    "tx": "0x32097804f977814e90da44bfa03b6295a0616a897441acec821a0600"
}

The following decoded tx:
 {
    "args": {
        "id": "30",
        "target": {
            "Address20": "0xf977814e90da44bfa03b6295a0616a897441acec"
        },
        "amount": "100,000"
    },
    "method": "transferKeepAlive",
    "section": "assets"
}

As shown also in the Deep Dive, you can copy paste the tx hash you see in the output and open [p-js apps](https://polkadot.js.org/apps/?rpc=wss%3A%2F%2Fsys.dotters.network%2Fstatemint#/extrinsics/decode) to submit it.

### DED transfer script - Create transfer, Sign & Submit
**Prerequisites**
- Have `nodejs` installed
- Install the required packages (keyring, util crypto) with `npm install...`

Add below code in a js file, e.g. `index.js` file

const {AssetTransferApi, constructApiPromise, TxResult} = require('@substrate/asset-transfer-api');
const { Keyring } = require('@polkadot/keyring');
const { cryptoWaitReady } = require('@polkadot/util-crypto');

const main = async () => {
	const { api, specName, safeXcmVersion } = await constructApiPromise('wss://polkadot-asset-hub-rpc.polkadot.io');
	const assetApi = new AssetTransferApi(api, specName, safeXcmVersion);

	let callInfo;
	try {
		callInfo = await assetApi.createTransferTransaction(
			'1000',
			'16VFgPxYcHQ95FLEPCF9rh89L5PYgNVuiwsfYacrZjjg6kcf', // Destination Account
			['30'],
			['100000000000'], // 10 DED
			{
				format: 'submittable',
				keepAlive: true,
			},
		);

		console.log(`The following call data that is returned:\n${JSON.stringify(callInfo, null, 4)}`);
	} catch (e) {
		console.error(e);
		throw Error(e);
	}

	const decoded = assetApi.decodeExtrinsic(callInfo.tx, 'call');
	console.log(`\nThe following decoded tx:\n ${JSON.stringify(JSON.parse(decoded), null, 4)}`);

	await cryptoWaitReady();

	const phrase = 'MNEMONIC PHRASE HERE';
	const keyring = new Keyring();
	const domi_keypair = keyring.addFromUri(phrase, { name: 'Domi' }, 'sr25519');

	await callInfo.tx.signAndSend(domi_keypair);
};

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

- Change `Destination Account` in line 13 with the address that you wish to send `DED` to
- Change the amount of `DED` in line 15 depending on how many `DED` you will like to send.
- Replace 'MNEMONIC PHRASE HERE' with the seed of the account from which you will sign&send this transaction.
- Caution: format in line 17 now is set to `submittable`
- Run with `node index.js`

**IMPORTANT NOTE** : The account from which you will sign & send this transaction needs to have enough `DOT` to cover the transaction fees.

**Troubleshooting**
If you get the error `TypeError: callInfo.tx.signAndSend is not a function` while trying to run this script, then you need to set the `format` option (line 17) to `submittable`.