How to save a list of objects with Proto DataStore

Question

If I have the following class, how can I save a list of it with Proto DataStore?

data class Tag(
    val id: int,
    val name: String
)

All guides that I saw were teaching how to save only a single object. Is it possible to have a list of it?

Answer 1

You should consider storing list of content in Room, Even proto-datastore isnt a proper solution to store complex stuff,

If you still want then, I will suggest you to restrict the data stored to 10-15 items

to the code --->

1. Create your proto file, repeated is used to create list type for Java

message Student {
  string id = 1;
  string name = 2;
}

message ClassRoom {
  string teacher = 1;
  repeated Student students  = 2; // repeated => list
}

2. Inside your proto-store,

dataStore.updateData { store ->
       store.toBuilder()
      .clearStudents() // clear previous list
      .setAllStudents(students)// add the new list
      .build()
}

if you want example checkout my sample app, read the data/domain layer https://github.com/ch8n/Jetpack-compose-thatsMine

Answer 2

You can encode your class object into json string by the help of kotlinx json library and store that string into datastore preference like below ->

@Serializable
data class EmployeeCorporateInfo(
    @SerialName("companyName")
    val companyName: String,
    @SerialName("employeeInfo")
    val employeeInfo: EmployeeInfo,
    @SerialName("firstName")
    val firstName: String,
    @SerialName("id")
    val id: String,
    @SerialName("lastName")
    val lastName: String,
    @SerialName("middleName")
    val middleName: String
)

@Serializable
data class EmployeeCorporates(val corporates:List<EmployeeCorporateInfo>)

Encode into JSON:

val employeeCorporates = EmployeeCorporates(emptyList()) 
val rawCorporate:String = Json.encodeToString(employeeCorporates ))

Store rawCorporate into preference data store. After whenever you need that get from preference data store and decode that string into our class object.

val employeeCorporates = Json.decodeFromString<EmployeeCorporate(rawCorporate)