Fuel

Fuel support is in beta stage. Here is a simple example.

Two important files:

• abis/fuel/orderbook-abi.json: project's ABI file in JSON format, used for code generation
• processor.ts: entry point for processing logic

You can also create an example project by running:

npx @sentio/cli@latest create -n <project name> --chain-type fuel

OnLog Handler

In your Sway code, if you define a statement as follows:

log(TradeEvent(...))

There will be related entries in the ABI file:

{
  ...
  "types": [
   ...
    "typeId": 20,
    "type": "struct TradeEvent",
    "components": [
      ...
    ]
  ],
  "loggedTypes": [
    ...
    {
      "logId": 27,
      "loggedType": {
        "name": "",
        "type": 20,
        "typeArguments": []
      }
    }
  ]
}

Then Sentio SDK will use this definition to generate a Processor where you can add your custom logic after the log is collected:

import { OrderbookProcessor } from "./types/fuel/OrderbookProcessor.js";

OrderbookProcessor.bind({
  chainId: FuelNetwork.TEST_NET,
  address: '0x0f0c1065a7b82d026069c5cf070b21ee65713fd1ac92ec1d25eacc3100187f78'
})
    .onLogTradeEvent(async (trade: FuelLog<TradeEventOutput>, ctx: FuelContext) => {
        const vol = trade.data.trade_price.mul(trade.data.trade_size).scaleDown(2 * 10)
        ctx.eventLogger.emit('trade', {
          distinctId: ctx.transaction?.sender,
          ...trade,
          vol: vol
        })
    })
    // ... other handlers

The handler takes two parameters:

• FuelLog<type>: includes the log type and log data, e.g., data: TradeEventOutput, which is the type generated by the official codegen, along with other utility fields like logId and receiptIndex. Note that one type could have different logId values if you log it in multiple places.
• FuelContext:
  • Contains tools for data submission, like eventLogger and meter, which record logs-in-processor and metrics-in-processors.
  • Contains the FuelTransaction, which extends from the official SDK's TransactionSummary and includes decoded logs.

Call Handling (WIP)

In addition to log handlers, you can also use function call handlers. Note that they only capture the entry transaction call:

OrderbookProcessor.bind({
  chainId: FuelNetwork.TEST_NET,
  address: '0x0f0c1065a7b82d026069c5cf070b21ee65713fd1ac92ec1d25eacc3100187f78'
})
    .onCallMatch_orders(async (orderTx, ctx) => {
      for (const log of orderTx.getLogsOfTypeTradeEvent()) {
        // record trade event
      }
    })

You can access arguments in orderTx.args or orderTx.argsObject, and results in orderTx.returnValue. All the objects are typed in the TypeScript code.

OnTransfer Handler

You can also track asset changes by using FuelAssetProcessor. You can filter by from, to, or assetId, all of which can be a single element or a list. The handler will then receive a FuelTransfer object, which represents all asset transfers (not limited by the filter) in the transactions that satisfy the filter.

import { BaseAssetId } from '@fuel-ts/address/configs'
import { FuelAssetProcessor, FuelNetwork } from "@sentio/sdk/fuel";

FuelAssetProcessor.bind({
  chainId: FuelNetwork.TEST_NET
}).onTransfer(
    {
      from: "0xd3fe20c8ff68a4054d8587ac170c40db7d1e200208a575780542bd9a7e3eec08",
      assetId: BaseAssetId
    },
    async (transfer: FuelTransfer, ctx) => {
      ...
    }
)

Handle Big Numbers

The Fuel SDK uses the BN type to represent big numbers, but when recording data, we might want to use a more readable number format. Use .asBigDecimal to convert to BigDecimal or use scaleDown with a decimal number. Read more in the general handle-big-numbers guide.