Agent Go Example: Transactions

This is an example of the Go Agent in action.

In this example we will use the agent go fetch transactions from the ICP main network. We will not be using the Rosetta API in this example, but instead will be using the agent to fetch transactions directly. We will explore the simple CLI that comes with the agent to generate a client.

This repository contains the end result that is described in the README. If you would like to follow along, you can clone this repository and checkout the start tag.

Setting Up Go

You can find more info on how to set up Go here.

go mod init github.com/aviate-labs/agent-go-example

Tree

.
├── LICENSE
├── README.md
└── go.mod

Installing the Agent CLI

We can install the CLI by running the following command:

go install github.com/aviate-labs/agent-go/cmd/goic@v0.3.0-alpha.2

More info on the CLI can be found here.

We can validate that the CLI is installed by running:

goic version

Generating a Client

The CLI provides two ways of generating clients, either by providing a configuration file or by providing the canister id that has an exposed candid interface method (this is not standardised, so it is not recommended).

We will be using the candid files that can be found here.

Getting the Candid Files

We can fetch the candid interfaces by running:

curl https://github.com/dfinity/ic/release-2023-11-01_23-01/rs/rosetta-api/icp_ledger/ledger.did > ledger.did
curl https://github.com/dfinity/ic/release-2023-11-01_23-01/rs/rosetta-api/icp_ledger/ledger_archive.did > ledger_archive.did

This should have generated two files, ledger.did and ledger_archive.did.

Tree

.
├── LICENSE
├── README.md
├── go.mod
├── ledger.did
└── ledger_archive.did

Generating the Client

We can generate the client by running:

mkdir ledger
goic generate did ledger.did ledger --output=ledger/agent.go --packageName=ledger

mkdir archive
goic generate did ledger_archive.did archive --output=archive/agent.go --packageName=archive

Tree

.
├── LICENSE
├── README.md
├── archive
│   └── agent.go
├── go.mod
├── ledger
│   └── agent.go
├── ledger.did
└── ledger_archive.did

If you open legder.go and archive.go you should see the generated code. You will also notice that some dependencies are missing. We can fetch these dependencies by running:

go get github.com/aviate-labs/agent-go@v0.3.0-alpha.2
go mod tidy

.
├── LICENSE
├── README.md
├── archive
│   └── agent.go
├── go.mod
├── go.sum
├── ledger
│   └── agent.go
├── ledger.did
└── ledger_archive.did

Fetching Transactions

Now that we have generated the client, we can use it to fetch transactions from the ICP main network.

Creating main.go

Create a file called main.go and add the following code:

package main

import "fmt"

func main() {
	fmt.Println("Hello, World!")
}

Tree

.
├── LICENSE
├── README.md
├── archive
│   └── agent.go
├── go.mod
├── go.sum
├── ledger
│   └── agent.go
├── ledger.did
├── ledger_archive.did
└── main.go

Setting Up the Client

We can now set up the client by adding the following code to main.go:

package main

import (
	"github.com/aviate-labs/agent-go"
	"github.com/aviate-labs/agent-go-example/ledger"
	"github.com/aviate-labs/agent-go/ic"
	"log"
)

func main() {
	// The default configuration is fine for most use cases, it uses the anonymous identity to create requests.
	ledgerAgent, err := ledger.NewAgent(ic.LEDGER_PRINCIPAL, agent.DefaultConfig)
	if err != nil {
		log.Fatal(err)
	}

	_ = ledgerAgent
}

Fetching The Block Height

The next step is to fetch the block height. We do not know yet what the last block is, so we query the block height first.

package main

import (
	"github.com/aviate-labs/agent-go"
	"github.com/aviate-labs/agent-go-example/ledger"
	"github.com/aviate-labs/agent-go/ic"
	"log"
)

func main() {
	ledgerAgent, err := ledger.NewAgent(ic.LEDGER_PRINCIPAL, agent.DefaultConfig)
	if err != nil {
		log.Fatal(err)
	}

	// We do not know yet what the last block is, so we query the block height first.
	blockHeight, err := ledgerAgent.QueryBlocks(ledger.GetBlocksArgs{})
	if err != nil {
		log.Fatal(err)
	}
	// oldestBlock = blockHeight.FirstBlockIndex // The first block that we can query the ledger.
	lastBlock := blockHeight.ChainLength // The last block that we can query the ledger.
	_ = lastBlock
}

Fetching Last 10 Transactions

Now that we know the last block, we can fetch the last 10 blocks. Based on the operation type we can determine what kind of transaction it is. We will only be looking at Transfer, Burn and Mint operations.

package main

import (
	"fmt"
	"github.com/aviate-labs/agent-go-example/ledger"
	"github.com/aviate-labs/agent-go/ic"
	"github.com/aviate-labs/agent-go/principal"
	"log"
)

func main() {
	ledgerAgent, err := ledger.NewAgent(ic.LEDGER_PRINCIPAL, agent.DefaultConfig)
	if err != nil {
		log.Fatal(err)
	}

	// We do not know yet what the last block is, so we query the block height first.
	blockHeight, err := ledgerAgent.QueryBlocks(ledger.GetBlocksArgs{})
	if err != nil {
		log.Fatal(err)
	}
	// oldestBlock = blockHeight.FirstBlockIndex // The first block that we can query the ledger.
	lastBlock := blockHeight.ChainLength // The last block that we can query the ledger.

	// Query the last 10 blocks.
	response, err := ledgerAgent.QueryBlocks(ledger.GetBlocksArgs{
		Start:  lastBlock - 10,
		Length: 10,
	})
	if err != nil {
		log.Fatal(err)
	}
	for i, block := range response.Blocks {
		operation := block.Transaction.Operation
		if transfer := operation.Transfer; transfer != nil {
			var from principal.AccountIdentifier
			copy(from[:], transfer.From)

			var to principal.AccountIdentifier
			copy(to[:], transfer.To)

			fmt.Printf("Block %d: %s -> %s: %.2f ICP.\n", int(lastBlock)+i, from, to, float64(transfer.Amount.E8s)/1e8)
		} else if burn := operation.Burn; burn != nil {
			var from principal.AccountIdentifier
			copy(from[:], burn.From)

			fmt.Printf("Block %d: %s: %.2f ICP burned.\n", int(lastBlock)+i, from, float64(burn.Amount.E8s)/1e8)
		} else if mint := operation.Mint; mint != nil {
			var to principal.AccountIdentifier
			copy(to[:], mint.To)

			fmt.Printf("Block %d: %s: %.2f ICP minted.\n", int(lastBlock)+i, to, float64(mint.Amount.E8s)/1e8)
		}
	}
}