How to handle GORM error at Delete function?

When performing database operations with GORM, proper error handling is crucial, especially during delete operations. Below are the steps to handle errors when using GORM's Delete function:

1. Using the Delete Function for Deletion

First, call GORM's Delete method to execute the deletion operation. Pass the model instance and deletion conditions.

go
result := db.Delete(&User{}, "id = ?", userID)

2. Checking for Errors

GORM's Delete method returns a *gorm.DB object containing operation results, including potential errors. Check the Error field to determine if an error occurred.

go
if result.Error != nil {
    // Handle error
    log.Printf("Delete operation failed: %v", result.Error)
    return result.Error
}

3. Verifying Affected Rows

Even without errors, no records may be deleted (e.g., if conditions match no records). Check the RowsAffected field to confirm actual deletions.

go
if result.RowsAffected == 0 {
    log.Println("No records found for deletion")
    // Return custom error or specific message
    return errors.New("no record found for deletion")
}

4. Complete Example

Below is a complete function example demonstrating error handling when deleting a user:

go
func deleteUser(db *gorm.DB, userID int) error {
    // Execute deletion
    result := db.Delete(&User{}, "id = ?", userID)

    // Check for errors
    if result.Error != nil {
        log.Printf("Delete operation failed: %v", result.Error)
        return result.Error
    }

    // Verify affected rows
    if result.RowsAffected == 0 {
        log.Println("No records found for deletion")
        return errors.New("no record found for deletion")
    }

    log.Printf("User %d successfully deleted", userID)
    return nil
}

Important Notes

• Validate Database Connection: Ensure the database connection is active before any operations.
• Use Transactions: For multi-step delete operations, employ transactions to maintain data consistency.
• Log Detailed Information: In production, log comprehensive details to facilitate issue tracking and diagnosis.

By following these steps, you can effectively manage potential errors in GORM's Delete function.