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Stellar & Soroban Quick Start

SubQuery TeamAbout 5 min

Stellar & Soroban Quick Start

The goal of this quick start guide is to give a quick intro to all features of our Stellar and Soroban indexer. The example project indexes all soroban transfer events on Stellar's Futurenet. It also indexes all account payments including credits and debits - it's a great way to quickly learn how SubQuery works on a real world hands-on example.

In the earlier Quickstart section , you should have taken note of three crucial files. To initiate the setup of a project from scratch, you can proceed to follow the steps outlined in the initialisation description.

Now, let's move forward and update these configurations.

Note

The final code of this project can be found hereopen in new window.

1. Update Your GraphQL Schema File

The schema.graphql file determines the shape of the data that you are using SubQuery to index, hence it's a great place to start. The shape of your data is defined in a GraphQL Schema file with various GraphQL entities.

Remove all existing entities and update the schema.graphql file as follows, here you can see we are indexing a variety of datapoints, including accounts, transfers, credit, debits, and payments.

type Account @entity {
  id: ID!
  firstSeenLedger: Int
  lastSeenLedger: Int
  sentTransfers: [Transfer] @derivedFrom(field: "from") # These are virtual properties to help us navigate to the correct foreign key of Transfer
  recievedTransfers: [Transfer] @derivedFrom(field: "to") # These are virtual properties to help us navigate to the correct foreign key of Transfer
  sentPayments: [Payment] @derivedFrom(field: "from") # These are virtual properties to help us navigate to the correct foreign key of Payment
  receivedPayments: [Payment] @derivedFrom(field: "to") # These are virtual properties to help us navigate to the correct foreign key of Payment
}

type Transfer @entity {
  id: ID!
  ledger: Int!
  date: Date!
  contract: String!
  from: Account!
  to: Account!
  value: BigInt!
}

type Payment @entity {
  id: ID!
  txHash: String!
  from: Account!
  to: Account!
  amount: String!
}

type Credit @entity {
  id: ID!
  account: Account!
  amount: String!
}

type Debit @entity {
  id: ID!
  account: Account!
  amount: String!
}

Since we have a one-to-many relationship, we define a foreign keys using from: Account! syntax.

Important

When you make any changes to the schema file, please ensure that you regenerate your types directory.

yarn
yarn codegen

You will find the generated models in the /src/types/models directory.

Check out the GraphQL Schema documentation to get in-depth information on schema.graphql file.

Now that you have made essential changes to the GraphQL Schema file, let’s move forward to the next file.

2. Update Your Project Manifest File

The Project Manifest (project.ts) file works as an entry point to your Stellar and Soroban projects. It defines most of the details on how SubQuery will index and transform the chain data. For Stellar/Soroban, there are three types of mapping handlers (and you can have more than one in each project):

  • BlockHandler: On each and every block, run a mapping function
  • TransactionHandlers: On each and every Stellar/Soroban transaction that matches optional filter criteria, run a mapping function
  • OperationHandler: On each and every Stellar operation action that matches optional filter criteria, run a mapping function
  • EffectHandler: On each and every Stellar effect action that matches optional filter criteria, run a mapping function
  • OperationHandler: On each and every Stellar operation action that matches optional filter criteria, run a mapping function
  • EventHandler: On each and every Soroban event action that matches optional filter criteria, run a mapping function

Note that the manifest file has already been set up correctly and doesn’t require significant changes, but you need to update the datasource handlers.

Since you are going to index all Payments (including credits and debits), as well as transfer events on Soroban, you need to update the datasources section as follows:

{
  dataSources: [
    {
      kind: StellarDatasourceKind.Runtime,
      /* Set this as a logical start block, it might be block 1 (genesis) or when your contract was deployed */
      startBlock: 1700000,
      mapping: {
        file: "./dist/index.js",
        handlers: [
          {
            handler: "handleOperation",
            kind: StellarHandlerKind.Operation,
            filter: {
              type: Horizon.OperationResponseType.payment,
            },
          },
          {
            handler: "handleCredit",
            kind: StellarHandlerKind.Effects,
            filter: {
              type: "account_credited",
            },
          },
          {
            handler: "handleDebit",
            kind: StellarHandlerKind.Effects,
            filter: {
              type: "account_debited",
            },
          },
          {
            handler: "handleEvent",
            kind: StellarHandlerKind.Event,
            filter: {
              /* You can optionally specify a smart contract address here
                contractId: "" */
              topics: [
                "transfer", // Topic signature(s) for the events, there can be up to 4
              ],
            },
          },
        ],
      },
    },
  ],
}

The above code indicates that you will be running a handleOperation mapping function whenever there is payment Stellar operation made. Additionally we run the handleCredit/handleDebit mapping functions whenever there are Stellar effects made of the respective types. Finally, we have a Soroban event handler, which looks for any smart contract events that match the provided topic filters, in this case it runs handleEvent whenever a event wth the transfer topic is detected.

Check out our Manifest File documentation to get more information about the Project Manifest (project.ts) file.

Next, let’s proceed ahead with the Mapping Function’s configuration.

3. Add a Mapping Function

Mapping functions define how chain data is transformed into the optimised GraphQL entities that we previously defined in the schema.graphql file.

Follow these steps to add a mapping function:

Navigate to the default mapping function in the src/mappings directory.

There are different classes of mapping functions for Stellar; Block handlers, Operation Handlers, and Effect Handlers.

Soroban has two classes of mapping functions; Transaction Handlers, and Event Handlers.

Update the mappingHandler.ts file as follows (note the additional imports):

import { Account, Credit, Debit, Payment, Transfer } from "../types";
import {
  StellarOperation,
  StellarEffect,
  SorobanEvent,
} from "@subql/types-stellar";
import { AccountCredited, AccountDebited } from "stellar-sdk/lib/types/effects";
import { Horizon } from "stellar-sdk";

export async function handleOperation(
  op: StellarOperation<Horizon.PaymentOperationResponse>,
): Promise<void> {
  logger.info(`Indexing operation ${op.id}, type: ${op.type}`);

  const fromAccount = await checkAndGetAccount(op.from, op.ledger.sequence);
  const toAccount = await checkAndGetAccount(op.to, op.ledger.sequence);

  const payment = Payment.create({
    id: op.id,
    fromId: fromAccount.id,
    toId: toAccount.id,
    txHash: op.transaction_hash,
    amount: op.amount,
  });

  fromAccount.lastSeenLedger = op.ledger.sequence;
  toAccount.lastSeenLedger = op.ledger.sequence;
  await Promise.all([fromAccount.save(), toAccount.save(), payment.save()]);
}

export async function handleCredit(
  effect: StellarEffect<AccountCredited>,
): Promise<void> {
  logger.info(`Indexing effect ${effect.id}, type: ${effect.type}`);

  const account = await checkAndGetAccount(
    effect.account,
    effect.ledger.sequence,
  );

  const credit = Credit.create({
    id: effect.id,
    accountId: account.id,
    amount: effect.amount,
  });

  account.lastSeenLedger = effect.ledger.sequence;
  await Promise.all([account.save(), credit.save()]);
}

export async function handleDebit(
  effect: StellarEffect<AccountDebited>,
): Promise<void> {
  logger.info(`Indexing effect ${effect.id}, type: ${effect.type}`);

  const account = await checkAndGetAccount(
    effect.account,
    effect.ledger.sequence,
  );

  const debit = Debit.create({
    id: effect.id,
    accountId: account.id,
    amount: effect.amount,
  });

  account.lastSeenLedger = effect.ledger.sequence;
  await Promise.all([account.save(), debit.save()]);
}

export async function handleEvent(event: SorobanEvent): Promise<void> {
  logger.info(`New transfer event found at block ${event.ledger}`);

  // Get data from the event
  // The transfer event has the following payload \[env, from, to\]
  // logger.info(JSON.stringify(event));
  const {
    topic: [env, from, to],
  } = event;

  const fromAccount = await checkAndGetAccount(from, event.ledger.sequence);
  const toAccount = await checkAndGetAccount(to, event.ledger.sequence);

  // Create the new transfer entity
  const transfer = Transfer.create({
    id: event.id,
    ledger: event.ledger.sequence,
    date: new Date(event.ledgerClosedAt),
    contract: event.contractId,
    fromId: fromAccount.id,
    toId: toAccount.id,
    value: BigInt(event.value.decoded!),
  });

  fromAccount.lastSeenLedger = event.ledger.sequence;
  toAccount.lastSeenLedger = event.ledger.sequence;
  await Promise.all([fromAccount.save(), toAccount.save(), transfer.save()]);
}

async function checkAndGetAccount(
  id: string,
  ledgerSequence: number,
): Promise<Account> {
  let account = await Account.get(id.toLowerCase());
  if (!account) {
    // We couldn't find the account
    account = Account.create({
      id: id.toLowerCase(),
      firstSeenLedger: ledgerSequence,
    });
  }
  return account;
}

Let’s understand how the above code works.

For the handleOperation mapping function, the function receives a new StellarOperation payload to which we add additional type safety from Horizon.PaymentOperationResponse. We then run the checkAndGetAccount to ensure that we create Account records for sending/receiving accounts if we don't already have them (it checks if it already exists before creating a new Account entity).

For the handleCredit and handleDebit mapping functions, the functions receives a new StellarEffect payload to which we add additional type safety from AccountCredited and AccountDebited types.

The handleEvent mapping function is for Soroban smart contracts, and the payload of data is stored as an array of properties.

Check out our Mappings documentation to get more information on mapping functions.

Note

For more information on mapping functions, please refer to our Mappings documentation.

Build Your Project

Next, build your work to run your new SubQuery project. Run the build command from the project's root directory as given here:

yarn
yarn build

Important

Whenever you make changes to your mapping functions, you must rebuild your project.

Now, you are ready to run your first SubQuery project. Let’s check out the process of running your project in detail.

Whenever you create a new SubQuery Project, first, you must run it locally on your computer and test it and using Docker is the easiest and quickiest way to do this.

Run Your Project Locally with Docker

The docker-compose.yml file defines all the configurations that control how a SubQuery node runs. For a new project, which you have just initialised, you won't need to change anything.

However, visit the Running SubQuery Locally to get more information on the file and the settings.

Run the following command under the project directory:

yarn
yarn start:docker

Note

It may take a few minutes to download the required images and start the various nodes and Postgres databases.

Query your Project

Next, let's query our project. Follow these three simple steps to query your SubQuery project:

  1. Open your browser and head to http://localhost:3000.

  2. You will see a GraphQL playground in the browser and the schemas which are ready to query.

  3. Find the Docs tab on the right side of the playground which should open a documentation drawer. This documentation is automatically generated and it helps you find what entities and methods you can query.

Try the following queries to understand how it works for your new SubQuery starter project. Don’t forget to learn more about the GraphQL Query language.

{
  query {
    transfers(first: 5, orderBy: VALUE_DESC) {
      totalCount
      nodes {
        id
        date
        ledger
        toId
        fromId
        value
      }
    }
    accounts(first: 5, orderBy: SENT_TRANSFERS_COUNT_DESC) {
      nodes {
        id
        sentTransfers(first: 5, orderBy: LEDGER_DESC) {
          totalCount
          nodes {
            id
            toId
            value
          }
        }
        firstSeenLedger
        lastSeenLedger
      }
    }
  }
}

You will see the result similar to below:


Note

The final code of this project can be found hereopen in new window.

What's next?

Congratulations! You have now a locally running SubQuery project that accepts GraphQL API requests for transferring data.

Tip

Find out how to build a performant SubQuery project and avoid common mistakes in Project Optimisation.

Click here to learn what should be your next step in your SubQuery journey.