Storing data to Room database

I have a question that,

Let's consider we have a app in which we are adding many categories (ex: shopping,study,public, etc..) at runtime , there is no limit of adding categories since we adding it at runtime while we use the app and storing in a RoomDatabase having one Entity class and Dao.

-> now my question arises here , In that categories(ex: shopping,study,public, etc..) there are lot of different items we will store , so how can we use Roomdatabase to store all these categories item .

so that when we will open the shopping category so it will show only shopping list and so on for other categories

Is it possible to save all data of these categories? ,since we are adding many categories and there sub data then how it is possible to make that much of DAO and ENTITY CLASS to save that much of sub data.

-> If we will use SHARED PREFENCES . then we can store all categories sub data into a unique keys(unique key can be a categories name). so if we add more and more categories then it will store data to categories unique name.

but how can we do in roomDatabase. Is it possible? if yes then how....?

i hope, i explained my question well

Dao Interface

@Dao
 interface Dao {

@Insert
fun insert(studentName: StudentsEntity): Long

@Insert
fun stdDetailsInsert(stdDetails: StudentDetailsEntity)

@Transaction
@Query("Select * from Student")
fun getAllStudent(): MutableList<WholeDataStudent>

@Query("Select * from Student")
fun getStudentName(): MutableList<StudentsEntity>

}

Entity Class

@Entity(tableName = "Student")
data class StudentsEntity(
val stdName: String
) {
@PrimaryKey(autoGenerate = true)
var stdId: Int = 0
}

@Entity
data class StudentDetailsEntity(

val detailsId: Int,
val stdAddress: String,
val phoneNo: String
) {
@PrimaryKey(autoGenerate = true)
var id: Int = 0
}

data class WholeDataStudent(
@Embedded val std: StudentsEntity,

@Relation(
    parentColumn = "stdId",
    entityColumn = "detailsId",
    entity = StudentDetailsEntity::class
)

val stdDetails: List<StudentDetailsEntity>
)

For your items in your different categories, can these items use the same Item Entity class template?
I can think of solutions for both scenarios.

Without further information, let me give you an idea for supporting adding categories (and corresponding items) dynamically and a common item class for all items.

Room (based on SQL) offers several ways of to define data relationships.

As far as I understand your problem:

• one category can have many items
• but each item belongs only to one category

If that holds true, then you have a one-to-many relationship in your data.

What Akash Bisht was pointing at: you should have another entity for your categories.
There, at minimum you need to store information such as the ID (primary key) and the name (string) of that category.
Then you can create categories dynamically and add them to this table. This can be as many categories as you want.
Then when creating your items inside this category, you just need to add the ID reference of the corresponding category in the Item entity, e.g. as a variable like categoryId

On the other hand you could also just store the category name directly in the Item entity. But this has the disadvantage that when you want to change, for example, your categories name, then you have to update all your items.

To then just get the items for one specific category, as you stated as requirements, you have at least 2 options:

1. write a SQL query that only selects items of a specific category
2. or you query a list of all your items and then filter them by a category

If your data for different categories is of types that can be stored in shared preferences (as you have mentioned). You also can handle that with this approach.