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Juno Quick Start

SubQuery TeamAbout 2 min

Juno Quick Start

The goal of this quick start guide is to adapt the standard starter project in the Juno Network and then begin indexing all votes on the Terra Developer Fundopen in new window (which also contributed to SubQuery) from Cosmos.


This network is based on the Cosmos SDK, which means you can index chain data via the standard Cosmos RPC interface.

Before we begin, make sure that you have initialised your project using the provided steps in the Start Here section. You must complete the suggested 4 stepsopen in new window for Cosmos users.


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

Your Project Manifest File

The Project Manifest file is an entry point to your project. It defines most of the details on how SubQuery will index and transform the chain data.

For Cosmos chains, there are four types of mapping handlers (and you can have more than one in each project):

  • BlockHanders: On each and every block, run a mapping function
  • TransactionHandlers: On each and every transaction, run a mapping function
  • MessageHandlers: On each and every message that matches optional filter criteria, run a mapping function
  • EventHanders: On each and every event 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 change the datasource handlers. This section lists the triggers that the manifest file looks for on the blockchain to start indexing.

  dataSources: [
      kind: CosmosDatasourceKind.Runtime,
      startBlock: 9700000,
      mapping: {
        file: "./dist/index.js",
        handlers: [
            handler: "handleEvent",
            kind: CosmosHandlerKind.Event,
            filter: {
              type: "execute",
              messageFilter: {
                type: "/cosmwasm.wasm.v1.MsgExecuteContract",
            handler: "handleMessage",
            kind: CosmosHandlerKind.Message,
            filter: {
              type: "/cosmwasm.wasm.v1.MsgExecuteContract",

The above code defines that you will be running a handleTerraDeveloperFund mapping function whenever there is a message with a vote contract call from the Terra Developer Fundopen in new window smart contract.

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

Update Your GraphQL Schema File

The schema.graphql file determines the shape of your data from SubQuery due to the mechanism of the GraphQL query language. Hence, updating the GraphQL Schema file is the perfect place to start. It allows you to define your end goal right at the start.

Update the schema.graphql file as follows. The aim is to index all votes on the Terra Developer Fundopen in new window.

type Vote @entity {
  id: ID! # id field is always required and must look like this
  blockHeight: BigInt!
  voter: String! # The address that voted
  proposalID: BigInt! # The proposal ID
  vote: Boolean! # If they voted to support or reject the proposal


Importantly, these relationships can not only establish one-to-many connections but also extend to include many-to-many associations. To delve deeper into entity relationships, you can refer to this section. If you prefer a more example-based approach, our dedicated Hero Course Module can provide further insights.

SubQuery simplifies and ensures type-safety when working with GraphQL entities, actions, and transactions.

yarn codegen

This action will generate a new directory (or update the existing one) named src/types. Inside this directory, you will find automatically generated entity classes corresponding to each type defined in your schema.graphql. These classes facilitate type-safe operations for loading, reading, and writing entity fields. You can learn more about this process in the GraphQL Schema section.

If you've expressed a preference to employ the Cosmos message based on the provided proto files, this command will also generate types for your listed protobufs and save them into src/types directory, providing you with more typesafety. For example, you can find Osmosis' protobuf definitions in the official documentationopen in new window. Read about how this is done in Cosmos Codegen from CosmWasm Protobufs and Cosmos Manifest File Configuration.

Now that you have made essential changes to the GraphQL Schema file, let’s go ahead with the next configuration.

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 proceed ahead with the Mapping Function’s configuration.

Add a Mapping Function

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

Navigate to the default mapping function in the src/mappings directory. You will see four exported functions: handleBlock, handleEvent, handleMessage, handleTransaction. Delete handleBlock, handleEvent, and handleTransaction functions as you will only deal with the handleMessage function.

The handleMessage function receives event data whenever an event matches the filters that you specified previously in the project.ts. Let’s update it to process all vote messages and save them to the GraphQL entity created earlier.

Update the handleMessage function as follows (note the additional imports):

import { Vote } from "../types";
import { CosmosMessage } from "@subql/types-cosmos";

export async function handleTerraDeveloperFund(
  message: CosmosMessage,
): Promise<void> {
  // Example vote

  const voteRecord = new Vote(`${message.tx.hash}-${message.idx}`);
  voteRecord.blockHeight = BigInt(message.block.block.header.height);
  voteRecord.voter = message.msg.sender;
  voteRecord.proposalID =; = === "yes";


Let’s understand how the above code works.

Here, the function receives a CosmosMessage which includes message data on the payload. We extract this data and then instantiate a new Vote entity defined earlier in the schema.graphql file. After that, we add additional information and then use the .save() function to save the new entity (SubQuery will automatically save this to the database).

Check out our Mappings documentation and get information on the mapping functions in detail.

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 build


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 start:docker


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 {
  votes(first: 3, orderBy: BLOCK_HEIGHT_DESC) {
    nodes {

You will see the result similar to below:

  "data": {
    "votes": {
      "nodes": [
          "id": "14B3EE22278C494DFE90EA440A4F049F2D39A31634F0062B0FF362DB2872A979-0",
          "blockHeight": "3246683",
          "voter": "juno1njyvry0t3j5dy4rr6ar5zfglg3cy2e8u745hl7",
          "vote": true
          "id": "23329451CAFF77D5A0416013045530011F4FAFEA94FEEF43784CDF0947B6CA90-0",
          "blockHeight": "3246670",
          "voter": "juno1ewq9l5ae69csh57j8sgjh8z37ypm3lt0jzamwy",
          "vote": true
          "id": "BEAB15E994A4E99BD0631DACF4716C5627E5D0C14E0848BF07A45609CEFB2F0D-0",
          "blockHeight": "3246665",
          "voter": "juno1az0ehz2e5emudyh8hx2qwtfely0lstzj08gg9j",
          "vote": true


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.


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.