generate preview image from pdf if no image given

controllers/shopItemController.go

@@ -5,6 +5,7 @@ import (
 	"net/http"
 	"strconv"
 	"path/filepath"
+	"os/exec"
 
 	"github.com/gin-gonic/gin"
 
@@ -66,6 +67,7 @@ func (rc *shopItemController) GetById(c *gin.Context) {
 }
 
 func (rc *shopItemController) NewShopItemFromForm(ctx *gin.Context) (models.ShopItem, error) {
+	defaultImagePath := "static/img/zine.jpg"
 	name := ctx.PostForm("name")
 	abstract := ctx.PostForm("abstract")
 	description := ctx.PostForm("description")
@@ -74,7 +76,7 @@ func (rc *shopItemController) NewShopItemFromForm(ctx *gin.Context) (models.Shop
 	variantValues := ctx.PostFormArray("variant-value[]")
 	tagIds := ctx.PostFormArray("tags[]")
 	image, err := ctx.FormFile("image")
-	dstImage := "static/img/zine.jpg"
+	dstImage := defaultImagePath
 
 	if err == nil {
 		dstImage = filepath.Join("static/uploads", image.Filename)
@@ -91,6 +93,16 @@ func (rc *shopItemController) NewShopItemFromForm(ctx *gin.Context) (models.Shop
   	if err := ctx.SaveUploadedFile(pdf, dstPdf); err != nil {
 			return models.ShopItem{}, fmt.Errorf("Could not save PDF")
   	}
+
+		if dstImage == defaultImagePath {
+			dstImage = dstPdf + ".preview.png"
+			cmd := exec.Command("pdftoppm", "-png", "-singlefile", dstPdf, dstPdf + ".preview")
+			_, err := cmd.Output()
+
+			if err != nil {
+				fmt.Println("Error during pdftoppm: ", err.Error())
+			}
+		}
 	}
 
 	if name == "" || description == "" {