add basic paper model/view/controller

paper weight is missing

models/paper.go

@@ -0,0 +1,74 @@
+package models
+
+import (
+	"fmt"
+	"github.com/gin-gonic/gin"
+	"gorm.io/gorm"
+	"strconv"
+	"strings"
+)
+
+type PaperSize string
+
+const (
+	A3   PaperSize = "A3"
+	A4   PaperSize = "A4"
+	A5   PaperSize = "A5"
+	SRA3 PaperSize = "SRA3"
+)
+
+func ParseSize(s string) (c PaperSize, err error) {
+	s = strings.ToUpper(s)
+	if s == "A3" {
+		return A3, nil
+	} else if s == "A4" {
+		return A4, nil
+	} else if s == "A5" {
+		return A5, nil
+	} else if s == "SRA3" {
+		return SRA3, nil
+	}
+
+	return c, fmt.Errorf("Cannot parse category %s", s)
+}
+
+type Paper struct {
+	gorm.Model
+	Name  string    `json:"name" binding:"required" gorm:"not null"`
+	Brand string    `json:"brand" binding:"required"`
+	Size  PaperSize `json:"size" binding:"required"`
+	Price float64   `json:"price" binding:"required"`
+}
+
+func NewPaper(ctx *gin.Context) (Paper, error) {
+	name := ctx.PostForm("name")
+	brand := ctx.PostForm("brand")
+	sizeTmp := ctx.PostForm("size")
+	priceTmp := ctx.PostForm("price")
+
+	price, err := strconv.ParseFloat(priceTmp, 64)
+
+	if err != nil {
+		return Paper{}, fmt.Errorf("Couldnt parse Price")
+	}
+
+	size, err := ParseSize(sizeTmp)
+
+	if err != nil {
+		return Paper{}, fmt.Errorf("Couldnt parse Size")
+	}
+
+	if name == "" || brand == "" {
+		return Paper{}, fmt.Errorf("Name or brand empty")
+	}
+
+	// Convert the price string to float64
+	tag := Paper{
+		Name:  name,
+		Brand: brand,
+		Size:  size,
+		Price: price,
+	}
+
+	return tag, nil
+}