Room is there any way to not insert/update value if null

Question

I've recentyly started using Room and I would like to know if when inserting or updating an Entitiy there's any way to check if the value is null, and in that case, do not insert it /update it.

What I want to do is something like

@Entity
data class Person{
    @PrimaryKey
    val id: Int,
    val name:String
    val surname:String
 }

Would it be possible in a simple way to perform an @Update operation for those fields which are not null? and those which are null keep them as tey are?

For example in an update perhaps I might have informed the id and the name, but in another update I might have informed the id and the surname. So what I want is to merge the information, but if possible without having to make a select query to check the values stored.

I've read the following post, but my doubt then it would be, is it possible to define an @Entity, with all the fields defined as the one I mentioned before and then have other entities to just update some fields, something like:

 @Entity(tableName = "person")
data class PersonUpdateSurname{
    @PrimaryKey
    val id: Int,
    val name:String
 }


@Entity(tableName = "person")
data class PersonUpdateSurname{
    @PrimaryKey
    val id: Int,
    val surname:String
 }

Is there a way to tell Room which is the original table structure?

score 2 · Accepted Answer · answered Sep 26 '20 at 19:31

Is there a way to tell Room which is the original table structure?

This question is not clear. Maybe there is some misunderstanding you have.

Try to follow next schema:

There should be only one Person-related data class annotated with Room-annotations - @Entity, @PrimaryKey and so on. In your case it is Person class.
All the rest mentioned auxiliary classes should be just POJO (plain data classes), since they are not being persisted. In your case - PersonName and PersoneSurname (with the fields you described but without Room's annotations).
In DAO use entity-parameter in @Update:

@Update(entity = Person::class)
fun updateName(personName: PersonName)

@Update(entity = Person::class)
fun updateSurname(personeSurname: PersonSurname)

In your Repository call method what you need. If you want to update only name - you use method updateName() and instance of PersonName class as a parameter, for only surname's update - method updateSurname() and instance of class PersonSurname.

Room is there any way to not insert/update value if null

1 Answers1