SubQuery

SubQuery is a highly regarded blockchain indexing service that is widely utilized within the Polkadot ecosystem. In this guide, we will offer a straightforward approach to indexing the transfer event using the SubQuery tool.

Prerequisites

Install Subql

To get started, we need to install the SubQuery tool provided by SubQuery itself. This tool allows us to create new subql project and modify the indexing rules as needed. To install this tool, we can use a package manager like npm or yarn. Let's assume we're using npm for this example:

npm install -g @subql/cli

Ensure Docker Compose Installed

Before we proceed, please make sure that Docker Compose is installed on your computer. SubQuery utilizes Docker Compose to set up the project environment. If you don't have Docker Compose installed, you can follow the Docker install documentation to install it for your specific operating system.

docker compose version

The output:

Docker Compose version v2.3.3

Indexing Transfer Event

Create Workaround

Let's create a new subquery project called example-with-subquery to organize and manage the project effectively. This project will serve as a workaround for implementing the indexing functionality.

subql init example-with-subquery

Select the network family as Substrate and the network as Darwinia, then follow the cli instructions to complete the project creation.

The output:

The ll example-with-subquery/is:

total 1.8M
drwxrwxr-x   3 bear bear 4.0K  9月 21 15:19 dist
drwxrwxr-x   2 bear bear 4.0K  9月 21 15:09 docker
-rw-rw-r--   1 bear bear 1.5K  9月 21 15:29 docker-compose.yml
-rw-rw-r--   1 bear bear 1.1K  9月 21 15:09 LICENSE
drwxr-xr-x 951 bear bear  36K  9月 21 15:17 node_modules
-rw-rw-r--   1 bear bear 1021  9月 21 15:09 package.json
-rw-r--r--   1 root root 1.7M  9月 21 15:17 package-lock.json
-rw-rw-r--   1 bear bear 1.5K  9月 21 15:09 project.yaml
-rw-rw-r--   1 bear bear 5.7K  9月 21 15:09 README.md
-rw-rw-r--   1 bear bear 1.4K  9月 21 15:09 schema.graphql
drwxrwxr-x   5 bear bear 4.0K  9月 21 15:19 src
-rw-rw-r--   1 bear bear  401  9月 21 15:09 tsconfig.json

By default, the indexing rule for the balance transfer event is already included in the project.yml file's handlers section. This means that you don't need to make any changes to the indexing logic if you want to index balance transfer events. However, if you wish to customize the indexing logic for this event, you can do so by writing your own handler in the **project.yml** file. This gives you the flexibility to modify the indexing behavior according to your specific requirements. See SubQuery Academy (Documentation) for much more technical details.

Build The Project

Enter the workaround and run the following command:

1. Install necessary packages

   cd example-with-subquery && npm install
   

2. Run Codegen

   npm run codegen
   

   The output:

   > example-with-subquery@0.0.4 codegen
   > subql codegen
   
   ===============================
   ---------Subql Codegen---------
   ===============================
   (node:996923) ExperimentalWarning: The Fetch API is an experimental feature. This feature could change at any time
   (Use `node --trace-warnings ...` to show where the warning was created)
   * Schema Transfer generated !
   * Schema Account generated !
   * Models index generated !
   * Types index generated !
   

3. Build Project

   npm run build
   

   The output:

   > example-with-subquery@0.0.4 build
   > subql build
   
   Building and packing code ...
   Done!
   

Start Indexing

Let's start up the indexing service by running the command:

docker compose up -d

The output:

WARN[0000] The "SUB_COMMAND" variable is not set. Defaulting to a blank string. 
[+] Running 3/3
 ✔ Container example-with-subquery-postgres-1        Healthy                                                                                                                                                                                                                                0.0s 
 ✔ Container example-with-subquery-subquery-node-1   Healthy                                                                                                                                                                                                                                0.0s 
 ✔ Container example-with-subquery-graphql-engine-1  Started

This indicates that the indexing service has been successfully set up. Then open your browser http://127.0.0.1:3000, paste the following query script into the left-hand pane.

query {
  transfers(
    orderBy: BLOCK_NUMBER_DESC
  ) {
    nodes{
      id
      amount
      from {
        id
      }
      to {
        id
      }
    }
  }
}

The indexing result is displayed in the right pane, as shown below:

Stop Indexing

To stop the indexing service, type the following command:

docker compose stop

The output:

WARN[0000] The "SUB_COMMAND" variable is not set. Defaulting to a blank string. 
[+] Stopping 3/3
 ✔ Container example-with-subquery-graphql-engine-1  Stopped                                                                                                                                                                                                                                0.3s 
 ✔ Container example-with-subquery-subquery-node-1   Stopped                                                                                                                                                                                                                                0.5s 
 ✔ Container example-with-subquery-postgres-1        Stopped