SwaprHQ / token-balances-subgraph

Overview

This subgraph code is designed to track token balances by address interacting and monitoring the Ethereum blockchain for events related to ERC-20 token transfers. It captures and processes Transfer events emitted by ERC-20 smart contracts and maintains data regarding token balances and accounts involved in these transfers.

How to Get Token Balances by Address

You can use this subgraph to query and retrieve token balances for specific accounts (addresses) within the supported blockchains.

Query the Subgraph:

Use The Graph's query mechanism to retrieve token balances for a particular address

Here's an example query in GraphQL format:

query {
  account(id: "YOUR_ACCOUNT_ADDRESS") {
    id
    balances {
      token {
        id
        name
        symbol
      }
      balance
    }
  }
}

Key Components

1. handleTransfer Function

The core functionality of this subgraph is encapsulated in the handleTransfer function. This function is called whenever a Transfer event is emitted by an ERC-20 token contract. It performs the following tasks:

• Ignoring Zero-Value Transfers: It ignores transfers with a value of zero, as these transfers do not affect token balances.

• Checking for Ignored Tokens: It checks if the token address (the address of the ERC-20 contract) is on the ignore list. If it is, the function returns without further processing.

• Getting or Creating ERC-20 Token Entity: It retrieves the ERC-20 token entity associated with the event's token address. If the token does not exist, it creates one.

• Ignoring Non-ERC-20 Tokens: If the token entity is not found (null), it assumes the token address is not a valid ERC-20 token and adds it to the ignore list.

• Getting or Creating Accounts: It retrieves or creates account entities for both the sender (from) and the receiver (to) of the token transfer.

• Updating Balances: It updates the token balances of both the sender and the receiver based on the transfer. The balance is adjusted according to the transfer value.

2. Ignored Tokens

The subgraph maintains a list of token addresses that should be ignored (i.e., not processed). When a token is added to this list, the subgraph will skip processing any future transfers involving that token.

Data Entities

The subgraph code utilizes various data entities to maintain information about ERC-20 tokens, accounts, and balances:

• ERC20Token: Represents ERC-20 tokens, including details such as symbol, name, and token address.

• Account: Represents Ethereum addresses that have interacted with ERC-20 tokens.

• Balance: Represents the token balance of an account for a specific ERC-20 token.

• IgnoredToken: Represents token addresses that should be ignored in future processing.