Add solution for Challenge 13 by blxxdclxud

challenge-13/submissions/blxxdclxud/solution-template.go

@@ -0,0 +1,165 @@
+package main
+
+import (
+	"database/sql"
+	"context"
+	"time"
+	"errors"
+
+	_ "github.com/mattn/go-sqlite3"
+)
+
+// Product represents a product in the inventory system
+type Product struct {
+	ID       int64
+	Name     string
+	Price    float64
+	Quantity int
+	Category string
+}
+
+// ProductStore manages product operations
+type ProductStore struct {
+	db *sql.DB
+}
+
+// NewProductStore creates a new ProductStore with the given database connection
+func NewProductStore(db *sql.DB) *ProductStore {
+	return &ProductStore{db: db}
+}
+
+// InitDB sets up a new SQLite database and creates the products table
+func InitDB(dbPath string) (*sql.DB, error) {
+	// TODO: Open a SQLite database connection
+	// TODO: Create the products table if it doesn't exist
+	// The table should have columns: id, name, price, quantity, category
+	db, err := sql.Open("sqlite3", dbPath)
+	if err != nil {
+	    return nil, err
+	}
+	ctx, _ := context.WithTimeout(context.Background(), 5 * time.Second)
+	if err = db.PingContext(ctx); err != nil {
+	    return nil, err
+	}
+
+	query := `CREATE TABLE IF NOT EXISTS products (
+	    id INTEGER PRIMARY KEY AUTOINCREMENT,
+	    name VARCHAR(255),
+	    price DOUBLE,
+	    quantity INT,
+	    category VARCHAR(255)
+	    );`
+	_, err = db.Exec(query)
+	if err != nil {
+	    return nil, err
+	}
+	return db, nil
+}
+
+// CreateProduct adds a new product to the database
+func (ps *ProductStore) CreateProduct(product *Product) error {
+	// TODO: Insert the product into the database
+	// TODO: Update the product.ID with the database-generated ID
+	query := "INSERT INTO products(name, price, quantity, category) VALUES ($1, $2, $3, $4) RETURNING id"
+	err := ps.db.QueryRow(query, product.Name, product.Price, product.Quantity, product.Category).Scan(&product.ID)
+	return err
+}
+
+// GetProduct retrieves a product by ID
+func (ps *ProductStore) GetProduct(id int64) (*Product, error) {
+	// TODO: Query the database for a product with the given ID
+	// TODO: Return a Product struct populated with the data or an error if not found
+	query := "SELECT * from products WHERE id = $1"
+	var p Product
+	err := ps.db.QueryRow(query, id).Scan(&p.ID, &p.Name, &p.Price, &p.Quantity, &p.Category)
+	if err != nil {
+	    return nil, err
+	}
+	return &p, nil
+}
+
+// UpdateProduct updates an existing product
+func (ps *ProductStore) UpdateProduct(product *Product) error {
+	// TODO: Update the product in the database
+	// TODO: Return an error if the product doesn't exist
+	query := "UPDATE products SET name=$2, price=$3, quantity=$4, category=$5 WHERE id = $1"
+	_, err := ps.db.Exec(query, product.Name, product.Price, product.Quantity, product.Category, product.ID)
+	return err
+}
+
+// DeleteProduct removes a product by ID
+func (ps *ProductStore) DeleteProduct(id int64) error {
+	// TODO: Delete the product from the database
+	// TODO: Return an error if the product doesn't exist
+	query := "DELETE FROM products WHERE id = $1"
+	_, err := ps.db.Exec(query, id)
+	return err
+}
+
+// ListProducts returns all products with optional filtering by category
+func (ps *ProductStore) ListProducts(category string) ([]*Product, error) {
+	// TODO: Query the database for products
+	// TODO: If category is not empty, filter by category
+	// TODO: Return a slice of Product pointers
+	// TODO: Query the database for a product with the given ID
+	// TODO: Return a Product struct populated with the data or an error if not found
+	query := "SELECT * from products WHERE category = $1"
+	if category == "" {
+	   query = "SELECT * from products" 
+	}
+	var res []*Product
+	rows, err := ps.db.Query(query, category)
+	if err != nil {
+	    return nil, err
+	}
+
+	for rows.Next() {
+	    p := &Product{}
+	    err := rows.Scan(&p.ID, &p.Name, &p.Price, &p.Quantity, &p.Category)
+	    if err != nil {
+	        return nil, err
+	    }
+
+	    res = append(res, p)
+	}
+
+	if err = rows.Err(); err != nil {
+	    return nil, err
+	}
+	return res, nil
+}
+
+// BatchUpdateInventory updates the quantity of multiple products in a single transaction
+func (ps *ProductStore) BatchUpdateInventory(updates map[int64]int) error {
+	// TODO: Start a transaction
+	// TODO: For each product ID in the updates map, update its quantity
+	// TODO: If any update fails, roll back the transaction
+	// TODO: Otherwise, commit the transaction
+	tx, _ := ps.db.BeginTx(context.Background(), nil)
+	defer tx.Rollback()
+	for id := range updates {
+	    query := "UPDATE products SET quantity=$1 WHERE id = $2"
+    	res, err := tx.Exec(query, updates[id], id)
+    	if err != nil {
+    	    tx.Rollback()
+    	    return err
+    	}
+
+    	rows, err := res.RowsAffected()
+    	if err != nil {
+    	    tx.Rollback()
+    	    return err
+    	}
+
+    	if rows == 0 {
+    	    tx.Rollback()
+    	    return errors.New("product not found")
+    	}
+	}
+	tx.Commit()
+	return nil
+}
+
+func main() {
+	// Optional: you can write code here to test your implementation
+}