Add solution for gin challenge-2-middleware by 0xMoonrise #1152
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WalkthroughImplements a Go Gin HTTP server in a single file providing an in-memory Article store, CRUD endpoints, an admin stats endpoint, and a layered set of middleware (request ID, logging, auth, CORS, rate limiting, content-type enforcement, error handling, request counting). Changes
Sequence Diagram(s)sequenceDiagram
participant Client as Client (HTTP)
participant Gin as Gin Server
participant MW as Middleware Chain
participant Store as In-memory Store
participant Logger as Logger
Client->>Gin: HTTP request (e.g., POST /articles)
Gin->>MW: enter middleware chain
MW->>MW: RequestIDMiddleware (assign UUID header)
MW->>Logger: LoggingMiddleware (start, record requestID)
MW->>MW: CORSMiddleware (handle OPTIONS / set headers)
MW->>MW: RateLimitMiddleware (check & decrement quota)
MW->>MW: ContentTypeMiddleware (validate application/json)
MW->>MW: AuthMiddleware (validate API key → role in ctx)
MW->>Gin: pass to handler if allowed
Gin->>Store: createArticle / update / fetch / delete
Store-->>Gin: return result
Gin->>Logger: LoggingMiddleware (record latency, status, requestID)
Gin-->>Client: HTTP response (APIResponse with requestID)
Note: rectangles colored via rgba are not required in this simple sequence flow. Estimated code review effort🎯 4 (Complex) | ⏱️ ~45 minutes Possibly related PRs
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Actionable comments posted: 5
🤖 Fix all issues with AI agents
In `@packages/gin/challenge-2-middleware/submissions/0xMoonrise/solution.go`:
- Around line 154-163: The middleware aborts the request but does not stop
execution: after the AbortWithStatusJSON call inside the API key check you must
immediately return to avoid running c.Set("role", r) and c.Next(); modify the
handler where the variables ok and r are checked so that when !ok you call
c.AbortWithStatusJSON(...) and then return from the handler, ensuring
unauthorized requests do not proceed.
- Around line 436-437: The update currently overwrites the article with
updatedArticle from the request body, which loses the original ID and CreatedAt;
before setting updatedArticle.UpdatedAt and writing back to articles[id-1], copy
the original article (e.g., orig := articles[id-1]) and set updatedArticle.ID =
orig.ID and updatedArticle.CreatedAt = orig.CreatedAt, then set
updatedArticle.UpdatedAt = time.Now() and assign articles[id-1] =
updatedArticle.
- Around line 38-54: The global articles slice and nextID need synchronization:
add a package-level sync.RWMutex named articlesMu and use
articlesMu.RLock()/RUnlock() for all read-only access of articles and nextID
(e.g., list/get handlers) and articlesMu.Lock()/Unlock() for all mutations
(e.g., create/update/delete handlers and when incrementing nextID); ensure every
function that reads or writes the articles slice or nextID refers to these locks
(use defer to release) so no concurrent handler accesses mutate the shared state
without locking.
- Around line 342-361: The handler incorrectly assumes IDs map to slice indices
(using articles[id-1]) which breaks after deletions; replace that lookup with
the existing helper findArticleByID (or change storage to map[int]Article) to
perform a proper ID-based lookup and return 404 if not found; specifically, in
the block using articles and APIResponse/c.JSON, call findArticleByID(id,
articles) to get the Article and a found flag (or lookup in map), and then
respond with http.StatusNotFound when not found, otherwise return the found
Article in the http.StatusOK APIResponse.
- Around line 287-298: ErrorHandlerMiddleware currently uses unsafe type
assertions on recovered and request_id which can panic; update the
CustomRecovery handler in ErrorHandlerMiddleware to use safe type checks (the
comma-ok idiom) for recovered (e.g., try recovered.(error) and fall back to
fmt.Errorf("%v", recovered) or recoveredString) and for requestID (check
c.Get("request_id") return values and use a default like empty string or
"unknown" if not present), then build APIResponse using those safe values
instead of direct assertions; reference ErrorHandlerMiddleware, recovered, and
the request_id key and ensure it handles non-error panic values and missing
request IDs gracefully.
♻️ Duplicate comments (1)
packages/gin/challenge-2-middleware/submissions/0xMoonrise/solution.go (1)
459-467: Same ID-index lookup issue as other handlers.This suffers from the same problem flagged in
getArticle- the ID-to-index mapping breaks with non-contiguous IDs. Switching to a map-based storage would resolve this across all handlers.
🧹 Nitpick comments (4)
packages/gin/challenge-2-middleware/submissions/0xMoonrise/solution.go (4)
202-210: Unused constructor parameters.The
requestsanddurationparameters are accepted but never used. The rate limit is hardcoded ingetVisitorat line 232. Either use these parameters or remove them.♻️ Proposed fix to use the parameters
+type RateLimiter struct { + visitors map[string]*visitor + mu sync.RWMutex + rate rate.Limit + burst int +} func NewRateLimiter(requests int, duration time.Duration) *RateLimiter { rl := &RateLimiter{ visitors: make(map[string]*visitor), + rate: rate.Every(duration / time.Duration(requests)), + burst: requests, } go rl.cleanupVisitors() return rl } func (rl *RateLimiter) getVisitor(ip string) *rate.Limiter { rl.mu.Lock() defer rl.mu.Unlock() v, exists := rl.visitors[ip] if !exists { - limiter := rate.NewLimiter(rate.Every(time.Minute), 100) + limiter := rate.NewLimiter(rl.rate, rl.burst) rl.visitors[ip] = &visitor{limiter, time.Now()} return limiter } // ... }
509-515: Unused function with incorrect boundary check.
- This function is never called - consider removing it or using it in the handlers to reduce duplication.
- Line 511:
id < 0should beid <= 0since ID 0 is invalid (IDs start at 1).♻️ Proposed fix
func findArticleByID(id int) (*Article, int) { - if id > len(articles) || id < 0 { + if id > len(articles) || id <= 0 { return nil, -1 } return &articles[id-1], id - 1 }
111-111: Use camelCase for variable names per Go conventions.
request_idshould berequestIDto follow Go naming conventions.
494-498: Consider tracking actual uptime.The
uptimevalue is hardcoded to"24h". For accurate stats, track the server start time and compute the actual uptime.var serverStartTime = time.Now() // In getStats: stats := map[string]interface{}{ "total_articles": len(articles), "total_requests": atomic.LoadInt64(&servedRequests), "uptime": time.Since(serverStartTime).String(), }
| // In-memory storage | ||
| var articles = []Article{ | ||
| {ID: 1, | ||
| Title: "Getting Started with Go", | ||
| Content: "Go is a programming language...", | ||
| Author: "John Doe", | ||
| CreatedAt: time.Now(), | ||
| UpdatedAt: time.Now()}, | ||
|
|
||
| {ID: 2, | ||
| Title: "Web Development with Gin", | ||
| Content: "Gin is a web framework...", | ||
| Author: "Jane Smith", | ||
| CreatedAt: time.Now(), | ||
| UpdatedAt: time.Now()}, | ||
| } | ||
| var nextID = 3 |
There was a problem hiding this comment.
Data race on shared mutable state.
The global articles slice and nextID counter are accessed and modified by multiple concurrent requests without synchronization. This will cause data races under concurrent load.
🔒 Proposed fix using sync.RWMutex
+var articlesMu sync.RWMutex
var articles = []Article{
{ID: 1,
Title: "Getting Started with Go",
Content: "Go is a programming language...",
Author: "John Doe",
CreatedAt: time.Now(),
UpdatedAt: time.Now()},
{ID: 2,
Title: "Web Development with Gin",
Content: "Gin is a web framework...",
Author: "Jane Smith",
CreatedAt: time.Now(),
UpdatedAt: time.Now()},
}
var nextID = 3Then wrap all reads with articlesMu.RLock()/RUnlock() and all writes with articlesMu.Lock()/Unlock().
🤖 Prompt for AI Agents
In `@packages/gin/challenge-2-middleware/submissions/0xMoonrise/solution.go`
around lines 38 - 54, The global articles slice and nextID need synchronization:
add a package-level sync.RWMutex named articlesMu and use
articlesMu.RLock()/RUnlock() for all read-only access of articles and nextID
(e.g., list/get handlers) and articlesMu.Lock()/Unlock() for all mutations
(e.g., create/update/delete handlers and when incrementing nextID); ensure every
function that reads or writes the articles slice or nextID refers to these locks
(use defer to release) so no concurrent handler accesses mutate the shared state
without locking.
packages/gin/challenge-2-middleware/submissions/0xMoonrise/solution.go
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| if len(articles) < id || id <= 0 { | ||
| c.JSON(http.StatusNotFound, APIResponse{ | ||
| Success: false, | ||
| Error: "Id not found", | ||
| }) | ||
| return | ||
| } | ||
|
|
||
| if (articles[id-1] == Article{}) { | ||
| c.JSON(http.StatusNotFound, APIResponse{ | ||
| Success: false, | ||
| Error: "Id not found", | ||
| }) | ||
| return | ||
| } | ||
|
|
||
| c.JSON(http.StatusOK, APIResponse{ | ||
| Success: true, | ||
| Data: articles[id-1], | ||
| }) |
There was a problem hiding this comment.
Article lookup by ID assumes contiguous array indices.
The logic articles[id-1] assumes article IDs directly map to array indices (ID 1 at index 0, ID 2 at index 1, etc.). This breaks after deletions since IDs remain unchanged but the array can have gaps or the mapping becomes inconsistent.
Consider using a map map[int]Article for O(1) lookups by ID, or use the existing findArticleByID helper (which is defined but unused).
♻️ Suggested approach using a map
-var articles = []Article{...}
+var articles = map[int]Article{
+ 1: {ID: 1, Title: "Getting Started with Go", ...},
+ 2: {ID: 2, Title: "Web Development with Gin", ...},
+}
func getArticle(c *gin.Context) {
// ...
- if len(articles) < id || id <= 0 {
- // ...
- }
- if (articles[id-1] == Article{}) {
+ article, exists := articles[id]
+ if !exists {
c.JSON(http.StatusNotFound, APIResponse{
Success: false,
Error: "Id not found",
})
return
}
- c.JSON(http.StatusOK, APIResponse{Success: true, Data: articles[id-1]})
+ c.JSON(http.StatusOK, APIResponse{Success: true, Data: article})
}🤖 Prompt for AI Agents
In `@packages/gin/challenge-2-middleware/submissions/0xMoonrise/solution.go`
around lines 342 - 361, The handler incorrectly assumes IDs map to slice indices
(using articles[id-1]) which breaks after deletions; replace that lookup with
the existing helper findArticleByID (or change storage to map[int]Article) to
perform a proper ID-based lookup and return 404 if not found; specifically, in
the block using articles and APIResponse/c.JSON, call findArticleByID(id,
articles) to get the Article and a found flag (or lookup in map), and then
respond with http.StatusNotFound when not found, otherwise return the found
Article in the http.StatusOK APIResponse.
…ution.go Co-authored-by: coderabbitai[bot] <136622811+coderabbitai[bot]@users.noreply.github.com>
…ution.go Co-authored-by: coderabbitai[bot] <136622811+coderabbitai[bot]@users.noreply.github.com>
…ution.go Co-authored-by: coderabbitai[bot] <136622811+coderabbitai[bot]@users.noreply.github.com>
1 participant
gin challenge-2-middleware Solution
Submitted by: @0xMoonrise
Package: gin
Challenge: challenge-2-middleware
Description
This PR contains my solution for gin challenge-2-middleware.
Changes
packages/gin/challenge-2-middleware/submissions/0xMoonrise/solution.goTesting
Thank you for reviewing my submission! 🚀