Add solution for gorm challenge-1-crud-operations by grozdovk

[grozdovk]

No description provided.

[coderabbitai]

Walkthrough

Three new Go programs are added across three challenges: a palindrome checker for challenge-17, a comprehensive generics package with data structures and utility functions for challenge-27, and a GORM-based CRUD service for the challenge-1 GORM exercise.

Changes

Cohort / File(s)	Change Summary
Challenge-17 Palindrome Checker challenge-17/submissions/grozdovk/solution-template.go	Introduces IsPalindrome function that normalizes input (lowercase, removes non-alphanumeric), reverses using rune slice manipulation, and compares with original. Main function prompts user, calls checker, and prints result.
Challenge-27 Generic Data Structures challenge-27/submissions/grozdovk/solution-template.go	Implements generic types (Pair, Stack, Queue, Set with comparable constraint) with constructors and methods. Adds generic utility functions (Filter, Map, Reduce, Contains, FindIndex, RemoveDuplicates). Includes ErrEmptyCollection sentinel error for empty-state operations.
GORM CRUD Service packages/gorm/challenge-1-crud-operations/submissions/grozdovk/solution.go	Defines User model with ID, Name, Email, Age, and timestamps. Provides ConnectDB for SQLite setup via GORM, and implements five CRUD functions (CreateUser, GetUserByID, GetAllUsers, UpdateUser, DeleteUser) with error handling.

Estimated code review effort

🎯 3 (Moderate) | ⏱️ ~22 minutes

• Challenge-27 generics package: Review multiple type definitions and methods with consistent patterns; validate generic constraints and error handling across Stack/Queue/Set operations.
• GORM CRUD service: Verify User model constraints (unique Email, age > 0), database connection setup, and proper error propagation in each CRUD operation.
• Challenge-17 palindrome: Confirm string normalization logic (case-insensitivity, character filtering) and two-pointer reversal correctness.

Possibly related PRs

• RezaSi/go-interview-practice#587: Implements the same Challenge-17 palindrome checker with identical normalization and comparison logic.
• RezaSi/go-interview-practice#720: Adds the same GORM Challenge-1 CRUD service with User model and database operation functions.
• RezaSi/go-interview-practice#55: Implements the Challenge-27 generics package with identical Pair, Stack, Queue, Set types and utility functions.

Pre-merge checks

❌ Failed checks (1 inconclusive)

Check name	Status	Explanation	Resolution
Description check	❓ Inconclusive	No pull request description was provided by the author, making it impossible to assess relevance to the changeset.	Provide a description explaining the changes, implementation approach, or any relevant context for the reviewers.

✅ Passed checks (2 passed)

Check name	Status	Explanation
Title check	✅ Passed	The PR title accurately describes the main change: adding a solution for the gorm challenge-1-crud-operations. While the PR also includes other solutions (challenge-17 and challenge-27), the title correctly identifies the primary focus.
Docstring Coverage	✅ Passed	No functions found in the changed files to evaluate docstring coverage. Skipping docstring coverage check.

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Actionable comments posted: 0

🧹 Nitpick comments (10)

challenge-17/submissions/grozdovk/solution-template.go (3)

8-21: Consider using a more flexible input method.

fmt.Scanln stops reading at the first whitespace, so multi-word inputs like "A man a plan a canal Panama" would only process "A". For comprehensive palindrome testing, consider using bufio.Scanner or fmt.Scan with a full line read.

Example refactor:

+import (
+	"bufio"
 	"fmt"
+	"os"
 	"strings"
+)

 func main() {
 	// Get input from the user
 	var input string
 	fmt.Print("Enter a string to check if it's a palindrome: ")
-	fmt.Scanln(&input)
+	scanner := bufio.NewScanner(os.Stdin)
+	if scanner.Scan() {
+		input = scanner.Text()
+	}

---

26-27: Remove the TODO comment.

The function is fully implemented, so the TODO comment should be removed.

-	// TODO: Implement this function
-	// 1. Clean the string (remove spaces, punctuation, and convert to lowercase)

---

28-42: Implementation is correct.

The palindrome logic correctly handles case insensitivity and filters non-alphanumeric characters. The two-step approach (clean then reverse-and-compare) works well.

Optional: You could optimize by using a two-pointer comparison instead of creating a reversed copy:

// After getting cleanedString and runes:
for i, j := 0, len(runes)-1; i < j; i, j = i+1, j-1 {
    if runes[i] != runes[j] {
        return false
    }
}
return true

This avoids allocating memory for the reversed string.

challenge-27/submissions/grozdovk/solution-template.go (6)

12-34: Pair implementation looks good.

The generic Pair struct and its methods are correctly implemented. Remember to remove the TODO comments on lines 20 and 29 since the implementation is complete.

---

40-97: Stack implementation is correct.

All Stack methods (Push, Pop, Peek, Size, IsEmpty) are properly implemented with appropriate error handling for empty stack operations.

Minor formatting inconsistencies on lines 65, 79, and 96: add spaces around the == operator for consistency with Go conventions (e.g., len(s.elements) == 0). Also, remove the TODO comments since the implementation is complete.

---

103-158: Queue implementation is functionally correct.

All Queue methods work as expected with proper error handling for empty queue operations.

Optional improvements:

• Add spaces around == operators (lines 128, 141, 157) for consistency
• Remove TODO comments since implementation is complete
• Consider that Dequeue at line 132 using q.elements[1:] can lead to memory retention in long-running scenarios, as the underlying array keeps references to dequeued elements. For production code, periodically copying to a fresh slice when the queue is smaller than the capacity would help, but for a learning exercise this is fine.

---

164-211: Set implementation and operations are correct.

The Set data structure and all its methods work properly. Union, Intersection, and Difference operations are implemented correctly.

Optional improvements:

• Consider using map[T]struct{} instead of map[T]any (line 167) to save memory, as you only need the keys
• In Elements() (line 206), preallocate the slice with capacity: make([]T, 0, len(s.elements)) for better performance
• Add spaces around comparison operators for consistency with Go style
• Remove TODO comments

---

213-254: Set operations are correctly implemented.

Union, Intersection, and Difference operations correctly handle the set algebra. The logic for each operation is sound.

Remember to remove the TODO comments on lines 215, 230, and 244.

---

260-325: Generic utility functions are well implemented.

All utility functions (Filter, Map, Reduce, Contains, FindIndex, RemoveDuplicates) correctly implement their expected behaviors. The use of generics makes these reusable across different types.

Minor items:

• Remove TODO comments (lines 262, 274, 284, 293, 304, 315)
• Add spaces around comparison operators for consistency

packages/gorm/challenge-1-crud-operations/submissions/grozdovk/solution.go (1)

38-84: CRUD helpers are correct; consider simplifying existence checks using RowsAffected

The CRUD functions are logically correct and propagate errors cleanly. CreateUser, GetUserByID, and GetAllUsers are already minimal and fine.

For UpdateUser and DeleteUser, you’re doing a First followed by Save/Delete. That enforces a “must exist” contract but costs an extra query and still has a small time‑of‑check/time‑of‑use gap. If you don’t strictly need a separate pre‑check, you could instead rely on RowsAffected to detect missing rows after a single operation, e.g.:

• For updates: run a single Update/Updates and return gorm.ErrRecordNotFound (or similar) when RowsAffected == 0.
• For deletes: run a single Delete and treat RowsAffected == 0 as “user not found”.

This would reduce DB round‑trips while keeping clear not‑found semantics, at the cost of slightly different GORM behavior (e.g., Updates vs Save regarding zero‑values), so worth aligning with the challenge requirements before changing.

📜 Review details

Configuration used: CodeRabbit UI

Review profile: CHILL

Plan: Pro

📥 Commits

Reviewing files that changed from the base of the PR and between ca8ea29 and ebcf025.

📒 Files selected for processing (3)

• challenge-17/submissions/grozdovk/solution-template.go (1 hunks)
• challenge-27/submissions/grozdovk/solution-template.go (1 hunks)
• packages/gorm/challenge-1-crud-operations/submissions/grozdovk/solution.go (1 hunks)

🔇 Additional comments (2)

packages/gorm/challenge-1-crud-operations/submissions/grozdovk/solution.go (2)

12-20: User model definition is clear and appropriately constrained

The struct captures primary key, uniqueness, not‑null, and positive age constraints cleanly and is a good fit for the CRUD exercise.

---

22-36: Proposed fix is unsafe and introduces new bugs — revise error handling strategy

The web search reveals critical issues with the proposed fix:

1. GORM ownership model: When you pass *sql.DB via sqlite.Dialector{Conn: sqlDB}, you (the caller) remain responsible for its lifecycle; GORM does not take ownership.

2. Unsafe to close sqlDB while gorm.DB is active: Closing the underlying *sql.DB while the returned *gorm.DB still references it shuts down the connection pool and causes GORM operations to fail. With SQLite, this can also trigger SQLITE_BUSY errors.

3. Critical flaw in the proposed fix: The diff closes sqlDB in the AutoMigrate() error branch (_ = sqlDB.Close(); return nil, err), but the original code returns db, err on that failure. This means closing sqlDB while the caller expects to receive a live *gorm.DB — the connection will be unusable.

The actual resource leak occurs only on gorm.Open() failure, where sqlDB is opened but never closed. The AutoMigrate() failure case is not a leak because the function returns db to the caller, who owns cleanup responsibility via db.DB().Close() at shutdown.

Corrected approach: Close sqlDB only on gorm.Open() failure:

 func ConnectDB() (*gorm.DB, error) {
 	sqlDB, err := sql.Open("sqlite", "test.db")
 	if err != nil {
 		return nil, err
 	}
 	
 	db, err := gorm.Open(sqlite.Dialector{Conn: sqlDB}, &gorm.Config{})
 	if err != nil {
+		_ = sqlDB.Close()
 		return nil, err
 	}
 	
 	err = db.AutoMigrate(&User{})
 	return db, err
 }

The caller must ensure db.DB().Close() is called at graceful shutdown; do not close sqlDB here on AutoMigrate() failure.

Likely an incorrect or invalid review comment.