Unique dish.{name, cafeteriaID} (#325)

* introduced an index and made sure that the dishes are unique
* added the correct migration for `dish_ratings` FK-binding
* modified the models.DishRating struct as well with the appropriate change

server/backend/cafeteria.go

@@ -409,12 +409,11 @@ func (s *CampusServer) CreateDishRating(ctx context.Context, input *pb.CreateDis
 	resPath := imageWrapper(input.Image, "dishes", dishInMensa.Dish)
 
 	rating := model.DishRating{
-		Comment:     input.Comment,
-		CafeteriaID: cafeteriaID,
-		DishID:      dishInMensa.Dish,
-		Points:      input.Points,
-		Timestamp:   time.Now(),
-		Image:       resPath,
+		Comment:   input.Comment,
+		DishID:    dishInMensa.Dish,
+		Points:    input.Points,
+		Timestamp: time.Now(),
+		Image:     resPath,
 	}
 	if err := tx.Create(&rating).Error; err != nil {
 		log.WithError(err).Error("while creating a new dishInMensa rating.")

server/backend/cron/dish_name_download.go

@@ -2,6 +2,7 @@ package cron
 
 import (
 	"encoding/json"
+	"errors"
 	"fmt"
 	"net/http"
 	"strings"
@@ -95,25 +96,26 @@ func downloadDailyDishes(c *CronService) {
 					CafeteriaID: v.Cafeteria,
 				}
 
-				var count int64
-				var dishId int64
-				if err := c.db.Model(&model.Dish{}).
-					Where("name = ? AND cafeteriaID = ?", dish.Name, dish.CafeteriaID).
-					Select("dish").
-					First(&dishId).
-					Count(&count).Error; err != nil {
-					log.WithError(err).Error("Error while checking whether this is already in database")
-				}
-				if count == 0 {
+				var dbDish model.Dish
+				if err := c.db.First(&dbDish, "name = ? AND cafeteriaID = ?", dish.Name, dish.CafeteriaID).Error; err != nil && errors.Is(err, gorm.ErrRecordNotFound) {
 					if err := c.db.Create(&dish).Error; err != nil {
-						log.WithError(err).Error("Error while creating new CanteenDish entry with name {}. CanteenDish won't be saved", dish.Name)
+						log.WithError(err).WithField("name", dish.Name).Error("Error while creating new CanteenDish entry. CanteenDish won't be saved")
 					}
 					addDishTagsToMapping(dish.Dish, dish.Name, c.db)
-					dishId = dish.Dish
+					dbDish = dish
+				} else if err != nil {
+					log.WithError(err).Error("Error while checking whether the dish is already in database")
 				}
+
+				if dbDish.Type != dish.Type {
+					if err := c.db.Where("dish = ?", dbDish.Dish).Updates(&dish).Error; err != nil {
+						log.WithError(err).WithField("from", dish.Type).WithField("to", dish.Type).Error("Error while updating dish to new type")
+					}
+				}
+
 				if weekliesWereAdded == 0 {
 					errCreate := c.db.Create(&model.DishesOfTheWeek{
-						DishID: dishId,
+						DishID: dbDish.Dish,
 						Year:   int32(year),
 						Week:   int32(week),
 						Day:    int32(weekDayIndex),

server/backend/migration/20240311000000.go

@@ -0,0 +1,45 @@
+package migration
+
+import (
+	"github.com/go-gormigrate/gormigrate/v2"
+	"gorm.io/gorm"
+)
+
+// migrate20240311000000
+// made sure that dishes have the correct indexes
+// changed how `dish_rating` is bound to `dish`
+func migrate20240311000000() *gormigrate.Migration {
+	return &gormigrate.Migration{
+		ID: "20240311000000",
+		Migrate: func(tx *gorm.DB) error {
+			// make sure that dish_rating is FK-bound to dish
+			if err := tx.Exec("alter table dish_rating modify dishID int").Error; err != nil {
+				return err
+			}
+			if err := tx.Exec("alter table dish_rating add constraint dish_rating_dish_dish_fk foreign key (dishID) references dish (dish) on update cascade on delete cascade").Error; err != nil {
+				return err
+			}
+			// because dishes already have a cafeteria, storing this again is not necessary
+			if err := tx.Exec("alter table dish_rating drop column cafeteriaID").Error; err != nil {
+				return err
+			}
+			// uniqueness
+			return tx.Exec("create unique index dish_name_cafeteriaID_uindex on dish (name, cafeteriaID)").Error
+		},
+		Rollback: func(tx *gorm.DB) error {
+			// make sure that dish_rating is FK-bound to dishes
+			if err := tx.Exec("alter table dish_rating drop constraint dish_rating_dish_dish_fk").Error; err != nil {
+				return err
+			}
+			if err := tx.Exec("alter table dish_rating modify dishID int not null").Error; err != nil {
+				return err
+			}
+			// because dishes already have a cafeteria, storing this agiain is not nessesary
+			if err := tx.Exec("alter table dish_rating add column cafeteriaID int not null").Error; err != nil {
+				return err
+			}
+			// uniqueness
+			return tx.Exec("drop index dish_name_cafeteriaID_uindex on dish").Error
+		},
+	}
+}

server/backend/migration/20240312000000.go

@@ -5,11 +5,11 @@ import (
 	"gorm.io/gorm"
 )
 
-// migrate20240212000000
+// migrate20240312000000
 // implemented a basic variant of spam protection
-func migrate20240212000000() *gormigrate.Migration {
+func migrate20240312000000() *gormigrate.Migration {
 	return &gormigrate.Migration{
-		ID: "20240212000000",
+		ID: "20240312000000",
 		Migrate: func(tx *gorm.DB) error {
 			if err := tx.Exec("alter table feedback modify email_id text charset utf8mb3 not null").Error; err != nil {
 				return err

server/backend/migration/migration.go

@@ -71,7 +71,8 @@ func manualMigrate(db *gorm.DB) error {
 		migrate20240102000000(),
 		migrate20240103000000(),
 		migrate20240207000000(),
-		migrate20240212000000(),
+		migrate20240311000000(),
+		migrate20240312000000(),
 	}
 	return gormigrate.New(db, gormigrateOptions, migrations).Migrate()
 }

server/model/dish.go

@@ -14,9 +14,9 @@ var (
 // Dish represents one dish fin a specific cafeteria
 type Dish struct {
 	Dish        int64  `gorm:"primary_key;AUTO_INCREMENT;column:dish;type:int;not null;" json:"dish"`
-	Name        string `gorm:"column:name;type:text;not null;" json:"name" `
+	Name        string `gorm:"column:name;type:text;not null;uniqueIndex:dish_name_cafeteriaID_uindex" json:"name" `
 	Type        string `gorm:"column:type;type:text;not null;" json:"type" `
-	CafeteriaID int64  `gorm:"column:cafeteriaID;foreignKey:cafeteria;type:int;not null;" json:"cafeteriaID"`
+	CafeteriaID int64  `gorm:"column:cafeteriaID;foreignKey:cafeteria;type:int;not null;uniqueIndex:dish_name_cafeteriaID_uindex" json:"cafeteriaID"`
 }
 
 // TableName sets the insert table name for this struct type

server/model/dish_rating.go

@@ -5,13 +5,13 @@ import (
 )
 
 type DishRating struct {
-	DishRating  int64     `gorm:"primary_key;AUTO_INCREMENT;column:dishRating;type:int;not null;" json:"dishRating"`
-	Points      int32     `gorm:"column:points;type:int;not null;" json:"points"`
-	CafeteriaID int64     `gorm:"column:cafeteriaID;foreignKey:cafeteria;type:int;not null;" json:"cafeteriaID"`
-	DishID      int64     `gorm:"column:dishID;foreignKey:dish;type:int;not null;" json:"dishID"`
-	Comment     string    `gorm:"column:comment;type:text;" json:"comment"`
-	Timestamp   time.Time `gorm:"column:timestamp;type:timestamp;not null;" json:"timestamp"`
-	Image       string    `gorm:"column:image;type:text;" json:"image"`
+	DishRating int64     `gorm:"primary_key;AUTO_INCREMENT;column:dishRating;type:int;not null;" json:"dishRating"`
+	Points     int32     `gorm:"column:points;type:int;not null;" json:"points"`
+	DishID     int64     `gorm:"column:dishID;type:int;not null;" json:"dishID"`
+	Dish       Dish      `gorm:"foreignKey:dishID;references:dish;constraint:OnUpdate:CASCADE,OnDelete:CASCADE;"`
+	Comment    string    `gorm:"column:comment;type:text;" json:"comment"`
+	Timestamp  time.Time `gorm:"column:timestamp;type:timestamp;not null;" json:"timestamp"`
+	Image      string    `gorm:"column:image;type:text;" json:"image"`
 }
 
 // TableName sets the insert table name for this struct type