refactors data access layer to use pop ORM for eager loading, adds book titles rented to renters in response body

bookish-server/mysql/rental.go

@@ -0,0 +1,81 @@
+package mysql
+
+import (
+	"database/sql"
+	"errors"
+	"fmt"
+	"time"
+
+	"github.com/davidlick/bookish/bookish-server/models"
+	"github.com/gobuffalo/nulls"
+	"github.com/gobuffalo/uuid"
+)
+
+// IsBookAvailable queries the database for available books.
+func (s *store) IsBookAvailable(title string) (available bool, err error) {
+	rr := []models.Rental{}
+	err = s.Where(fmt.Sprintf("book_title = '%s'", title)).Where("return_date IS NULL").All(&rr)
+	if err != nil {
+		// If no records are returned then the book is available for rent.
+		if errors.Is(sql.ErrNoRows, err) {
+			return true, nil
+		}
+
+		return false, err
+	}
+
+	// If 5 books are rented out this book is not available.
+	if len(rr) > 4 {
+		return false, nil
+	}
+
+	return true, nil
+}
+
+// RenterAlreadyCheckedOut queries the database for the given renterId and title. If a record is returned checkedOut will be true.
+func (s *store) RenterAlreadyCheckedOut(renterId uuid.UUID, title string) (checkedOut bool, err error) {
+	rr := []models.Rental{}
+	err = s.Where(fmt.Sprintf("renter_id = '%s'", renterId)).
+		Where(fmt.Sprintf("book_title = '%s'", title)).
+		Where("return_date IS NULL").
+		All(&rr)
+	if err != nil {
+		// If no records are returned then the book is available for rent.
+		if errors.Is(sql.ErrNoRows, err) {
+			return false, nil
+		}
+
+		return false, err
+	}
+
+	// If 5 books are rented out this book is not available.
+	if len(rr) == 0 {
+		return false, nil
+	}
+
+	return true, nil
+}
+
+// CheckoutBook inserts a record indicating the book is checked out to the renter.
+func (s *store) CheckoutBook(renterId uuid.UUID, title string) error {
+	r := models.Rental{BookTitle: title, RenterID: renterId, RentalDate: time.Now()}
+	err := s.Create(&r)
+	return err
+}
+
+// ReturnBook sets the return_date field to now indicating the book has been returned.
+func (s *store) ReturnBook(renterId uuid.UUID, title string) error {
+	r := models.Rental{}
+	err := s.Where(fmt.Sprintf("renter_id = '%s'", renterId)).
+		Where(fmt.Sprintf("book_title = '%s'", title)).
+		Where("return_date IS NULL").
+		First(&r)
+	if err != nil {
+		return ErrNotFound
+	}
+
+	r.ReturnDate = nulls.Time{Time: time.Now(), Valid: true}
+
+	err = s.Save(&r)
+	return err
+}