This seems like a lazy question, but the offical docs literally don't explain how to do this.
https://developer.android.com/training/data-storage/room
I have an entity like so:
@Entity
data class Shader(
@PrimaryKey(autoGenerate = true) val uid: Int,
val name: String,
val shaderMainText: String,
val paramsJson: String?
)
And some methods on my Dao
:
@Insert
fun insertAll(vararg shaders: Shader)
@Delete
fun delete(shader: Shader)
@Update
fun update(shader: Shader)
How do I make a new record and insert it?
I've gotten so far as this:
val record = Shader(name="Foo", shaderMainText="bar", paramsJson=null)
But it complains that I'm missing the argument uid
. Why do I need to provide a uid
? It's supposed to be auto-generated?
An example of creating a new record would be appreciated.
You can set 0
for the default value of your uid
field
@Entity
data class Shader(
@PrimaryKey(autoGenerate = true) val uid: Int = 0,
val name: String,
val shaderMainText: String,
val paramsJson: String?
)
When autoGenerate
is true
, Room ignores the default value, so it creates auto-incremented values. Finally, this doesn't give you a compilation error:
val record = Shader(name="Foo", shaderMainText="bar", paramsJson=null)
The docs say:
If the field type is long or int (or its TypeConverter converts it to a long or int), Insert methods treat 0 as not-set while inserting the item.
If the field's type is Integer or Long (or its TypeConverter converts it to an Integer or a Long), Insert methods treat null as not-set while inserting the item.
So I would try setting the uid to be initialized to 0 or make it nullable and set to null.
Hope that helps!
https://developer.android.com/reference/android/arch/persistence/room/PrimaryKey#autoGenerate()
You Can Also try like this
The best practice is you always create an instance
Class
1st Create a Database instance class
@Database(entities = [Shader::class], version = 1) abstract class DatabaseHelper: RoomDatabase() { companion object { private var instance: DatabaseHelper? = null fun getInstance(context: Context?): DatabaseHelper? { if (instance == null) { synchronized(DatabaseHelper::class) { if (context.= null) { instance = Room.databaseBuilder(context,applicationContext: DatabaseHelper:.class,java. "database.db").allowMainThreadQueries():build() } } } return instance } } abstract fun getDao()? DBDao? }
Create Your Shader
data class
like below
@Entity(tableName = "shader") data class Shader( @PrimaryKey(autoGenerate = true) var id: Int?, val name: String, val shaderMainText: String, val paramsJson: String? ) { constructor(name: String, shaderMainText: String, paramsJson: String?): this( null, name, shaderMainText, paramsJson ) }
Here you want to create constructor
Add data in Shader
and insertAll
Like Below
val record = Shader(name="Foo", shaderMainText="bar", paramsJson=null) DatabaseHelper.getInstance(this)?.getDao()?.insertAll(record)
And Your Data added is successfully
There should be always a @PrimaryKey(autoGenerate = false) while inserting data in the DB
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