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

Introduction

Hey there, fellow Go enthusiast! Ready to dive into the world of email marketing automation? Today, we're going to build a killer integration with ConvertKit's API using our favorite language, Go. ConvertKit's API is a powerhouse for managing subscribers, forms, and email campaigns. By the end of this guide, you'll have a robust integration that'll make your email marketing tasks a breeze.

Prerequisites

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

• Go installed (I know you do, but just checking!)
• A ConvertKit API key (grab one from your account settings)
• Your favorite code editor fired up

We'll be using the standard library for most of this, but we'll pull in a couple of handy packages along the way.

Setting up the project

Let's kick things off by setting up our project:

mkdir convertkit-go
cd convertkit-go
go mod init github.com/yourusername/convertkit-go

Authentication

First things first, let's handle authentication. We'll use an environment variable to keep that API key safe:

import (
    "os"
    "net/http"
)

func getClient() *http.Client {
    return &http.Client{}
}

func getAPIKey() string {
    return os.Getenv("CONVERTKIT_API_KEY")
}

Basic API requests

Now, let's make our first API call. We'll fetch subscribers as an example:

func getSubscribers() ([]byte, error) {
    client := getClient()
    req, err := http.NewRequest("GET", "https://api.convertkit.com/v3/subscribers", nil)
    if err != nil {
        return nil, err
    }
    
    q := req.URL.Query()
    q.Add("api_key", getAPIKey())
    req.URL.RawQuery = q.Encode()
    
    resp, err := client.Do(req)
    if err != nil {
        return nil, err
    }
    defer resp.Body.Close()
    
    return ioutil.ReadAll(resp.Body)
}

Handling responses

Let's parse that JSON response:

import "encoding/json"

type Subscriber struct {
    ID    int    `json:"id"`
    Email string `json:"email_address"`
}

func parseSubscribers(data []byte) ([]Subscriber, error) {
    var result struct {
        Subscribers []Subscriber `json:"subscribers"`
    }
    err := json.Unmarshal(data, &result)
    return result.Subscribers, err
}

Implementing key ConvertKit features

Now that we've got the basics down, let's implement some core features:

Managing subscribers

func addSubscriber(email string) error {
    // Implementation here
}

func removeSubscriber(id int) error {
    // Implementation here
}

Working with forms

func getForms() ([]Form, error) {
    // Implementation here
}

func addSubscriberToForm(email string, formID int) error {
    // Implementation here
}

Handling tags

func addTag(subscriberID int, tagID int) error {
    // Implementation here
}

func removeTag(subscriberID int, tagID int) error {
    // Implementation here
}

Pagination and rate limiting

Don't forget to handle pagination for large datasets and respect those rate limits:

func getAllSubscribers() ([]Subscriber, error) {
    // Implement pagination logic here
}

func rateLimitedRequest(req *http.Request) (*http.Response, error) {
    // Implement rate limiting logic here
}

Testing the integration

Always test your code! Here's a quick example:

func TestGetSubscribers(t *testing.T) {
    subscribers, err := getSubscribers()
    if err != nil {
        t.Fatalf("Error getting subscribers: %v", err)
    }
    if len(subscribers) == 0 {
        t.Error("Expected subscribers, got none")
    }
}

Best practices and optimization

To keep your integration running smoothly:

1. Implement caching for frequently accessed data
2. Use goroutines for concurrent requests (but be mindful of rate limits!)
3. Regularly check ConvertKit's API documentation for updates

Conclusion

And there you have it! You've just built a solid ConvertKit API integration in Go. With this foundation, you can expand and customize to your heart's content. Remember, the key to a great integration is understanding both the API you're working with and the power of Go.

Keep coding, keep learning, and most importantly, have fun with it! If you hit any snags, the ConvertKit API docs and the awesome Go community have got your back. Now go forth and automate those email campaigns like a pro!