Remove some duplication in API handlers

api/context.go

@@ -0,0 +1,19 @@
+package api
+
+import (
+	"errors"
+	"net/http"
+
+	"github.com/gin-gonic/gin"
+)
+
+func getID(ctx *gin.Context) (uint, error) {
+	id, ok := ctx.MustGet("user").(uint)
+	if !ok {
+		err := errors.New("an error occured while retrieving ID from context")
+		ctx.AbortWithError(http.StatusInternalServerError, err)
+		return 0, err
+	}
+
+	return id, nil
+}