Add base models.

compose/app/src/main/java/ru/ulstu/is/pmu/student/model/Level.kt

@@ -1,10 +1,36 @@
 package ru.ulstu.`is`.pmu.student.model
 
-import java.io.Serializable
+import androidx.room.ColumnInfo
+import androidx.room.Entity
+import androidx.room.Ignore
+import androidx.room.PrimaryKey
 
+@Entity(
+    tableName = "levels"
+)
 data class Level(
+    @PrimaryKey(autoGenerate = true)
+    val uid: Long?,
+    @ColumnInfo(name = "level")
     val level: Int,
-) : Serializable
+){
+    @Ignore
+    constructor(
+        level: Int
+    ) : this(null, level)
+
+    override fun equals(other: Any?): Boolean {
+        if (this === other) return true
+        if (javaClass != other?.javaClass) return false
+        other as Level
+        if (uid != other.uid) return false
+        return true
+    }
+
+    override fun hashCode(): Int {
+        return (uid ?: -1) as Int
+    }
+}
 
 fun getLevels(): List<Level> {
     return listOf(

compose/app/src/main/java/ru/ulstu/is/pmu/student/model/LevelWithTanks.kt

@@ -0,0 +1,16 @@
+package ru.ulstu.`is`.pmu.student.model
+
+import androidx.room.Embedded
+import androidx.room.Relation
+
+//one to many for level and tanks
+data class LevelWithTanks (
+    @Embedded
+    val level: Level,
+
+    @Relation(
+        parentColumn = "uid",
+        entityColumn = "levelId"
+    )
+    val tanks: List<Tank>
+)

compose/app/src/main/java/ru/ulstu/is/pmu/student/model/NaationWithTanks.kt

@@ -0,0 +1,16 @@
+package ru.ulstu.`is`.pmu.student.model
+
+import androidx.room.Embedded
+import androidx.room.Relation
+
+//one to many for nation and tanks
+data class NaationWithTanks (
+    @Embedded
+    val nation: Nation,
+
+    @Relation(
+        parentColumn = "uid",
+        entityColumn = "nationId"
+    )
+    val tanks: List<Tank>
+)

compose/app/src/main/java/ru/ulstu/is/pmu/student/model/Nation.kt

@@ -1,10 +1,37 @@
 package ru.ulstu.`is`.pmu.student.model
 
+import androidx.room.ColumnInfo
+import androidx.room.Entity
+import androidx.room.Ignore
+import androidx.room.PrimaryKey
 import java.io.Serializable
 
+@Entity(
+    tableName = "nations"
+)
 data class Nation(
+    @PrimaryKey(autoGenerate = true)
+    val uid: Long?,
+    @ColumnInfo(name = "name")
     val name: String,
-) : Serializable
+) {
+    @Ignore
+    constructor(
+        name: String
+    ) : this(null, name)
+
+    override fun equals(other: Any?): Boolean {
+        if (this === other) return true
+        if (javaClass != other?.javaClass) return false
+        other as Nation
+        if (uid != other.uid) return false
+        return true
+    }
+
+    override fun hashCode(): Int {
+        return (uid ?: -1) as Int
+    }
+}
 
 fun getNations(): List<Nation> {
     return listOf(

compose/app/src/main/java/ru/ulstu/is/pmu/student/model/Tank.kt

@@ -1,19 +1,52 @@
 package ru.ulstu.`is`.pmu.student.model
 
+import androidx.room.ColumnInfo
+import androidx.room.Entity
+import androidx.room.Ignore
+import androidx.room.PrimaryKey
 import java.io.Serializable
 
+@Entity(
+    tableName = "tanks"
+)
 data class Tank(
+    @PrimaryKey(autoGenerate = true)
+    val uid: Long?,
+    @ColumnInfo(name = "name")
     val name: String,
+    @ColumnInfo(name = "price")
     val price: Int,
-    val level: Int,
-    val nation: String
-) : Serializable
+    @ColumnInfo(name = "levelId")
+    val levelId: Long?,
+    @ColumnInfo(name = "nationId")
+    val nationId: Long?
+) {
+    @Ignore
+    constructor(
+        name: String,
+        price: Int,
+        level: Level,
+        nation: Nation
+    ) : this(null, name, price, level.uid, nation.uid)
+
+    override fun equals(other: Any?): Boolean {
+        if (this === other) return true
+        if (javaClass != other?.javaClass) return false
+        other as Tank
+        if (uid != other.uid) return false
+        return true
+    }
+
+    override fun hashCode(): Int {
+        return (uid ?: -1) as Int
+    }
+}
 
 fun getTanks(): List<Tank> {
     return listOf(
-        Tank("T-38-85", 970000, 6, "СССР"),
-        Tank("M3 Lee", 140000, 4, "США"),
-        Tank("Foch B", 6100000, 10, "Франция")
+        //Tank("T-38-85", 970000, 6, "СССР"),
+        //Tank("M3 Lee", 140000, 4, "США"),
+        //Tank("Foch B", 6100000, 10, "Франция")
     )
 }