Step by Step Guide to Building a FreshBooks API Integration in Go

Introduction

Hey there, fellow Go enthusiast! Ready to dive into the world of FreshBooks API integration? You're in for a treat. We'll be using the awesome toggl/go-freshbooks package to make our lives easier. Let's get cracking!

Prerequisites

Before we jump in, make sure you've got:

• Go installed (I know, obvious, right?)
• A FreshBooks account with API credentials
• A decent grasp of Go and RESTful APIs

Got all that? Great! Let's move on.

Setting up the project

First things first, let's create a new Go project:

mkdir freshbooks-integration
cd freshbooks-integration
go mod init freshbooks-integration

Now, let's grab the toggl/go-freshbooks package:

go get github.com/toggl/go-freshbooks

Authenticating with FreshBooks API

Alright, time to get those API credentials working for us. Head over to your FreshBooks account and grab your API key and secret. Then, let's initialize the FreshBooks client:

import (
    "github.com/toggl/go-freshbooks"
)

client := freshbooks.NewClient("YOUR_API_KEY", "YOUR_API_SECRET")

Basic API operations

Now that we're all set up, let's dive into some basic operations.

Fetching account information

account, err := client.Accounts.Get(context.Background(), "YOUR_ACCOUNT_ID")
if err != nil {
    log.Fatal(err)
}
fmt.Printf("Account Name: %s\n", account.Name)

Listing clients

clients, err := client.Clients.List(context.Background(), "YOUR_ACCOUNT_ID", nil)
if err != nil {
    log.Fatal(err)
}
for _, client := range clients.Clients {
    fmt.Printf("Client Name: %s\n", client.Name)
}

Creating an invoice

invoice := &freshbooks.Invoice{
    CustomerID: 12345,
    Lines: []freshbooks.InvoiceLine{
        {
            Name:     "Awesome Service",
            UnitCost: freshbooks.Amount{Amount: "100.00"},
            Quantity: 1,
        },
    },
}

createdInvoice, err := client.Invoices.Create(context.Background(), "YOUR_ACCOUNT_ID", invoice)
if err != nil {
    log.Fatal(err)
}
fmt.Printf("Invoice created with ID: %d\n", createdInvoice.ID)

Advanced operations

Ready to level up? Let's tackle some more advanced stuff.

Updating and deleting resources

Updating a client:

updatedClient := &freshbooks.Client{
    ID:   12345,
    Name: "Updated Client Name",
}

client, err := client.Clients.Update(context.Background(), "YOUR_ACCOUNT_ID", updatedClient)
if err != nil {
    log.Fatal(err)
}

Deleting an invoice:

err := client.Invoices.Delete(context.Background(), "YOUR_ACCOUNT_ID", 67890)
if err != nil {
    log.Fatal(err)
}

Handling pagination

options := &freshbooks.ListOptions{
    Page:    1,
    PerPage: 30,
}

for {
    clients, err := client.Clients.List(context.Background(), "YOUR_ACCOUNT_ID", options)
    if err != nil {
        log.Fatal(err)
    }

    for _, client := range clients.Clients {
        // Process each client
    }

    if clients.Pages.Page >= clients.Pages.Pages {
        break
    }
    options.Page++
}

Error handling and rate limiting

if err != nil {
    if freshbooksErr, ok := err.(*freshbooks.Error); ok {
        fmt.Printf("FreshBooks API Error: %s\n", freshbooksErr.Message)
        if freshbooksErr.StatusCode == 429 {
            // Handle rate limiting
            time.Sleep(time.Second * 5)
            // Retry the request
        }
    } else {
        log.Fatal(err)
    }
}

Best practices

Here are some tips to keep your code clean and efficient:

1. Structure your code: Create separate packages for different FreshBooks resources.
2. Implement caching: Store frequently accessed data to reduce API calls.
3. Handle API responses efficiently: Use Go's concurrency features for parallel processing.

Testing your integration

Don't forget to test! Here's a quick example of a unit test:

func TestCreateInvoice(t *testing.T) {
    // Set up mock client
    mockClient := &MockFreshBooksClient{}
    
    // Create a test invoice
    invoice := &freshbooks.Invoice{
        CustomerID: 12345,
        Lines: []freshbooks.InvoiceLine{
            {
                Name:     "Test Service",
                UnitCost: freshbooks.Amount{Amount: "100.00"},
                Quantity: 1,
            },
        },
    }

    // Test the CreateInvoice function
    createdInvoice, err := CreateInvoice(mockClient, "TEST_ACCOUNT_ID", invoice)
    
    assert.NoError(t, err)
    assert.NotNil(t, createdInvoice)
    assert.Equal(t, 67890, createdInvoice.ID)
}

For integration testing, use the FreshBooks sandbox environment to avoid messing with your production data.

Deployment considerations

When deploying your integration:

1. Secure your API credentials: Use environment variables or a secure key management system.
2. Implement proper logging and monitoring to track API usage and errors.

Conclusion

And there you have it! You're now equipped to build a robust FreshBooks API integration in Go. Remember, the toggl/go-freshbooks package documentation is your friend for more detailed information.

Happy coding, and may your invoices always be paid on time!