Implemented data classes for database optimisations

app/src/main/java/com/denizk0461/studip/model/CanteenOffer.kt

@@ -3,9 +3,10 @@ package com.denizk0461.studip.model
 import androidx.room.Entity
 import androidx.room.PrimaryKey
 
-@Entity(tableName = "offers")
+//@Entity(tableName = "offers")
 data class CanteenOffer(
-    @PrimaryKey val id: Int,
+//    @PrimaryKey val id: Int,
+    val id: Int,
     val date: String,
     val dateId: Int, // gives every item on the same day the same ID for easier filtering
 //    val canteen: Int,

app/src/main/java/com/denizk0461/studip/model/OfferCanteen.kt

@@ -1,6 +1,12 @@
 package com.denizk0461.studip.model
 
+import androidx.room.Entity
+import androidx.room.PrimaryKey
+
+@Entity(
+    tableName = "offer_canteen",
+)
 data class OfferCanteen(
-    val id: Int,
+    @PrimaryKey val id: Int,
     val canteen: String,
 )

app/src/main/java/com/denizk0461/studip/model/OfferCategory.kt

@@ -1,8 +1,30 @@
 package com.denizk0461.studip.model
 
+import androidx.room.ColumnInfo
+import androidx.room.Entity
+import androidx.room.ForeignKey
+import androidx.room.PrimaryKey
+
+@Entity(
+    tableName = "offer_category",
+    foreignKeys = [
+        ForeignKey(
+            OfferDate::class,
+            ["id"],
+            ["date_id"],
+            ForeignKey.CASCADE,
+        ),
+        ForeignKey(
+            OfferCanteen::class,
+            ["id"],
+            ["canteen_id"],
+            ForeignKey.CASCADE,
+        ),
+    ]
+)
 data class OfferCategory(
-    val id: Int,
-    val dateId: Int,
-    val canteenId: Int,
+    @PrimaryKey val id: Int,
+    @ColumnInfo(name = "date_id") val dateId: Int,
+    @ColumnInfo(name = "canteen_id") val canteenId: Int,
     val category: String,
 )

app/src/main/java/com/denizk0461/studip/model/OfferDate.kt

@@ -1,6 +1,12 @@
 package com.denizk0461.studip.model
 
+import androidx.room.Entity
+import androidx.room.PrimaryKey
+
+@Entity(
+    tableName = "offer_date",
+)
 data class OfferDate(
-    val id: Int,
+    @PrimaryKey val id: Int,
     val date: String,
 )

app/src/main/java/com/denizk0461/studip/model/OfferItem.kt

@@ -1,8 +1,24 @@
 package com.denizk0461.studip.model
 
+import androidx.room.ColumnInfo
+import androidx.room.Entity
+import androidx.room.ForeignKey
+import androidx.room.PrimaryKey
+
+@Entity(
+    tableName = "offer_item",
+    foreignKeys = [
+        ForeignKey(
+            OfferCategory::class,
+            ["id"],
+            ["category_id"],
+            ForeignKey.CASCADE,
+        ),
+    ]
+)
 data class OfferItem(
-    val id: Int,
-    val categoryId: Int,
+    @PrimaryKey val id: Int,
+    @ColumnInfo(name = "category_id") val categoryId: Int,
     val title: Int,
     val price: String,
     val isFair: Boolean,