Tutorial: Build a GitHub API Client

Build a GitHub API client step by step, connecting HTTPC's core concepts. Approximately 30 minutes to complete.

You will learn:

• Creating clients and using configuration presets
• Sending GET/POST requests and handling JSON responses
• Using the domain client to manage API base URLs
• Adding middleware for logging and metrics
• Handling errors and retries
• Result response objects and automatic management

Step 1: Basic Request

Install dependencies and create main.go:

go get github.com/cybergodev/httpc

package main

import (
    "fmt"
    "log"

    "github.com/cybergodev/httpc"
)

func main() {
    result, err := httpc.Get("https://api.github.com/repos/golang/go")
    if err != nil {
        log.Fatal(err)
    }

    fmt.Println(result.StatusCode()) // 200
    fmt.Println(result.Body())       // JSON response
}

Key points:

• Package-level function httpc.Get requires no client creation, suitable for quick validation
• Result is created fresh per request, reclaimed by GC, no manual release needed

Step 2: Parsing JSON Responses

type Repo struct {
    FullName    string `json:"full_name"`
    Description string `json:"description"`
    Stars       int    `json:"stargazers_count"`
    Language    string `json:"language"`
}

result, err := httpc.Get("https://api.github.com/repos/golang/go")
if err != nil {
    log.Fatal(err)
}

var repo Repo
if err := result.Unmarshal(&repo); err != nil {
    log.Fatal(err)
}

fmt.Printf("%s (Stars %d)\n", repo.FullName, repo.Stars)
fmt.Printf("Language: %s\n", repo.Language)
fmt.Printf("Description: %s\n", repo.Description)

Key points:

• result.Unmarshal(&v) directly parses JSON responses into structs
• Define Go structs that correspond to API responses

Step 3: Creating a Domain Client

All GitHub API endpoints are under https://api.github.com. Use a domain client to avoid repeating the URL:

client, err := httpc.NewDomain("https://api.github.com")
if err != nil {
    log.Fatal(err)
}
defer client.Close()

if err := client.SetHeader("Authorization", "Bearer "+os.Getenv("GITHUB_TOKEN")); err != nil {
    log.Fatal(err)
}

// Request paths are relative to baseURL
result, err := client.Get("/repos/golang/go",
    httpc.WithHeader("Accept", "application/vnd.github+json"),
)
if err != nil {
    log.Fatal(err)
}

Key points:

• NewDomain creates a scoped client; paths are relative to baseURL
• SetHeader sets persistent headers included with every request
• WithHeader passed as a request option applies only to that request
• Domain client automatically manages cookies

Step 4: Sending Data (Create Issue)

type CreateIssueRequest struct {
    Title string `json:"title"`
    Body  string `json:"body"`
}

newIssue := CreateIssueRequest{
    Title: "Bug report",
    Body:  "Found a bug in the API response",
}

result, err := client.Post("/repos/owner/repo/issues",
    httpc.WithJSON(newIssue),
)
if err != nil {
    log.Fatal(err)
}

if !result.IsSuccess() {
    log.Fatalf("Creation failed: %d %s", result.StatusCode(), result.Body())
}

var created struct {
    Number int    `json:"number"`
    URL    string `json:"html_url"`
}
result.Unmarshal(&created)
fmt.Printf("Issue #%d created: %s\n", created.Number, created.URL)

Key points:

• WithJSON(data) automatically serializes and sets Content-Type
• result.IsSuccess() checks for 2xx status codes

Step 5: Adding Middleware

Add logging and request IDs to the client:

// Configure middleware
cfg := httpc.DefaultConfig()
cfg.Middleware.Middlewares = []httpc.MiddlewareFunc{
    httpc.LoggingMiddleware(func(format string, args ...any) {
        log.Printf("[HTTP] "+format, args...)
    }),
    httpc.RecoveryMiddleware(),
    httpc.RequestIDMiddleware("X-Request-ID", nil),
}

// Pass configuration to NewDomain to create a domain client with middleware
client, err := httpc.NewDomain("https://api.github.com", cfg)
if err != nil {
    log.Fatal(err)
}
defer client.Close()

if err := client.SetHeader("Authorization", "Bearer "+os.Getenv("GITHUB_TOKEN")); err != nil {
    log.Fatal(err)
}

result, err := client.Get("/repos/golang/go",
    httpc.WithHeader("Accept", "application/vnd.github+json"),
)
if err != nil {
    log.Fatal(err)
}

var repo Repo
result.Unmarshal(&repo)
fmt.Printf("%s: Stars %d\n", repo.FullName, repo.Stars)

Key points:

• Middleware is configured in MiddlewareConfig.Middlewares
• LoggingMiddleware records request logs
• RecoveryMiddleware prevents panic crashes
• RequestIDMiddleware generates a unique ID for each request

Step 6: Error Handling and Retry

result, err := client.Get("/repos/golang/go")
if err != nil {
    var clientErr *httpc.ClientError
    if errors.As(err, &clientErr) {
        switch clientErr.Type {
        case httpc.ErrorTypeTimeout:
            log.Println("Request timeout, retry later")
        case httpc.ErrorTypeNetwork:
            log.Println("Network error")
        case httpc.ErrorTypeTLS:
            log.Println("TLS error")
        default:
            log.Printf("HTTP error: %s", clientErr.Error())
        }

        if clientErr.IsRetryable() {
            log.Println("This error can be automatically retried")
        }
    }
    return
}

// Handle HTTP status codes
switch {
case result.IsSuccess():
    // 2xx success
case result.StatusCode() == 401:
    log.Println("Token expired or invalid")
case result.IsClientError():
    log.Printf("Client error: %d", result.StatusCode())
case result.IsServerError():
    log.Printf("Server error: %d (attempted %d times, including first request)",
        result.StatusCode(), result.Meta.Attempts)
}

Configure retry strategy:

cfg := httpc.DefaultConfig()
cfg.Retry.MaxRetries = 5
cfg.Retry.Delay = 2 * time.Second
cfg.Retry.BackoffFactor = 2.0
cfg.Retry.EnableJitter = true

Key points:

• HTTPC separates network errors from HTTP status codes
• ClientError provides error classification and retryability checks
• 408, 429, 500, 502, 503, 504 are automatically retried by default

Step 7: File Download (Download Release Package)

dlCfg := httpc.DefaultDownloadConfig()
dlCfg.FilePath = "go1.22.0.linux-amd64.tar.gz"
dlCfg.Overwrite = true
dlCfg.ProgressCallback = func(downloaded, total int64, speed float64) {
    pct := float64(downloaded) / float64(total) * 100
    fmt.Printf("\rDownload progress: %.1f%% (%.2f MB/s)", pct, float64(speed)/1024/1024)
}

result, err := client.Download(
    context.Background(),
    "https://go.dev/dl/go1.22.0.linux-amd64.tar.gz",
    dlCfg,
)
if err != nil {
    log.Fatal(err)
}

fmt.Printf("\nDownload complete: %s (%d bytes)\n",
    result.FilePath,
    result.BytesWritten,
)

Step 8: Concurrent Requests

Fetch multiple repository details simultaneously:

func fetchRepos(ctx context.Context, repos []string) error {
    client, _ := httpc.New(httpc.PerformanceConfig())
    defer client.Close()

    results := make([]*httpc.Result, len(repos))
    errs := make([]error, len(repos))

    var wg sync.WaitGroup
    for i, name := range repos {
        wg.Add(1)
        go func(idx int, repo string) {
            defer wg.Done()
            r, err := client.Request(ctx, "GET", fmt.Sprintf("https://api.github.com/repos/%s", repo))
            results[idx] = r
            errs[idx] = err
        }(i, name)
    }
    wg.Wait()

    for i, err := range errs {
        if err != nil {
            return err
        }

        var repo Repo
        results[i].Unmarshal(&repo)
        fmt.Printf("%s: Stars %d\n", repo.FullName, repo.Stars)
    }
    return nil
}

TIP

PerformanceConfig() provides a large connection pool configuration suitable for high-concurrency scenarios. Result is created fresh per request and reclaimed by GC.

Complete Example

Full code integrating the above steps:

package main

import (
    "errors"
    "fmt"
    "log"
    "os"
    "time"

    "github.com/cybergodev/httpc"
)

type Repo struct {
    FullName    string `json:"full_name"`
    Description string `json:"description"`
    Stars       int    `json:"stargazers_count"`
    Language    string `json:"language"`
}

func main() {
    token := os.Getenv("GITHUB_TOKEN")

    cfg := httpc.DefaultConfig()
    cfg.Retry.MaxRetries = 3
    cfg.Retry.Delay = 1 * time.Second
    cfg.Middleware.Middlewares = []httpc.MiddlewareFunc{
        httpc.LoggingMiddleware(func(format string, args ...any) {
            log.Printf("[HTTP] "+format, args...)
        }),
        httpc.RecoveryMiddleware(),
    }

    client, err := httpc.New(cfg)
    if err != nil {
        log.Fatal(err)
    }
    defer client.Close()

    // Fetch repository information
    result, err := client.Get("https://api.github.com/repos/golang/go",
        httpc.WithHeader("Authorization", "Bearer "+token),
    )
    if err != nil {
        var clientErr *httpc.ClientError
        if errors.As(err, &clientErr) && clientErr.IsRetryable() {
            log.Fatal("Request failed (after retries):", err)
        }
        log.Fatal(err)
    }

    if result.IsSuccess() {
        var repo Repo
        result.Unmarshal(&repo)
        fmt.Printf("%s\n", repo.FullName)
        fmt.Printf("   Stars %d | Language: %s\n", repo.Stars, repo.Language)
        fmt.Printf("   %s\n", repo.Description)
        fmt.Printf("   Duration: %s (attempted %d times, including first request)\n",
            result.Meta.Duration, result.Meta.Attempts)
    }
}

Next Steps

• Request and Response - Complete request options reference
• Middleware Chain - Custom middleware development
• Retry and Fault Tolerance - Advanced retry strategies
• Performance Optimization - Production tuning
• Production Checklist - Security best practices