Wildcard Transfer Example

This example demonstrates different approaches to indexing ERC20 transfer events, showcasing both auto-generated and custom entity handling.

The indexer will:

Automatically store all Transfer events in the generated entity table
Log when it sees DAI or USDT transfers
Create a new example entity for each transfer event

Key Components

1. Auto-Generated Entity Handling (`/output` folder)

Contains entities automatically generated by the solidity-events-to-typeorm package
The TransferEntity_fab013d9 is auto-generated from the Transfer event ABI
These entities are automatically populated - no custom listener required!
Extends BlockchainEventEntity which provides common blockchain event fields

2. Custom Entity Handling (`/custom` folder)

Contains manually created entities for custom data storage
Demonstrates how to store additional/transformed data alongside auto-generated entities
In this example, ExampleEntity is used to demonstrate custom storage

3. Event Listeners

The example implements two different listeners:

Simple Console Logger (subscriptions.ts):

onEvent('*:Transfer', {
  onIndex: async (payload) => {
    // Filters and logs USDT and DAI transfers
  },
});

Custom Entity Storage (transfer-subscriber.ts):

@Injectable()
export class TransferSubscriber extends AbstractEventSubscriber {
  readonly eventPattern = '*:Transfer';
 
  async onIndex(payload: LogEvent, context: LogContext): Promise<void> {
    // Creates and stores a new ExampleEntity for each transfer
  }
}

4. Configuration

The indexer is configured in indexerConfig to:

Listen to Transfer events from any contract
Start from block 22229952
Track transfers from specific contracts (DAI and USDT)
Enable both auto-generated and custom entity storage

How It Works

Auto-Generated Indexing:
- Transfer events are automatically indexed into transfer_fab013d9 table
- No custom code needed for basic transfer data storage
- Handles all common event fields (block number, transaction hash, etc.)
Custom Processing:
- The subscriptions.ts listener filters and logs DAI/USDT transfers
- The TransferSubscriber demonstrates custom entity creation
- Each transfer triggers storage of a new example entity with random data

Example Transactions

You can view example transfers that this indexer should print "DAI" or "USDT" for here:

Setup and Usage

Set up environment variables - copy .env.example to .env and replace with your variables
Install dependencies:

pnpm install

Run the indexer:

pnpm start

Project Structure

src/
├── output/                 # Auto-generated entities and migrations
│   └── entities/          # Contains TransferEntity_fab013d9
├── custom/                 # Custom entities and migrations
│   └── entities/          # Contains ExampleEntity
├── subscriptions.ts       # Basic transfer event listener
├── transfer-subscriber.ts # Custom entity storage listener
└── indexer.config.ts     # Indexer configuration

This example demonstrates the flexibility of the indexer, showing both automatic event indexing and custom data processing approaches.

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