objectbox / objectbox/objectbox-java

Entities in Backlink ToMany reappearing after removing

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bug
Dominant language
Java
Stars
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Description

Describe the bug
When trying to remove entities from a One-To-Many relationship, they keep reappearing in the database after put() when first removing from the relationship and afterwards from box

Basic info (please complete the following information):

  • ObjectBox version: 3.1.0
  • Reproducibility: always
  • Device: Galaxy S10 (Android 11), OnePlus 6T (Android 11), Pixel 4 (Android 12)
  • OS: Android 11 and 12

To Reproduce
Steps to reproduce the behavior:

  1. Create 2 entities with a 1:N relationship (one and many)
  2. Add some entities to the ToMany (many) of the other (one).
  3. Remove 1 entity from the relationship with one.many.removeById(id)
  4. Remove the entity from the box box.remove(id)
  5. Put the parent (one) in the box again (overriding it)

Expected behavior
No matter the order, if an entity gets deleted from the box and the relation and is nowhere to be found, it should not reappear in the box.

Code
My Repo
Example code where I tested the issue in a Kotlin project

fun main(args: Array<String>) {
    val store: BoxStore = MyObjectBox.builder().name("objectbox-notes-db").build()
    val imageBox = store.boxFor<Image>().also { it.removeAll() }
    val propertyBox = store.boxFor<Property>().also { it.removeAll() }
    val originalImage = Image()
    imageBox.put(originalImage)
    originalImage.apply {
        properties.addAll(listOf(
            Property(name = "h1"),
            Property(name = "h2"),
            Property(name = "h3")
        ))
    }
    imageBox.put(originalImage)
    println("Boxed Properties: " + propertyBox.all.map { it.id })
    println("Original Image Properties: " + originalImage.properties.map { it.id })
    val removedID = propertyBox.all.first().id
    println("Removing id ${removedID}")
    val image = imageBox.get(originalImage.id).also {
        it.properties.removeById(removedID) //changing the order of these 2 will make 
        propertyBox.remove(propertyBox.all.first().id) // it work as expected
        it.properties.applyChangesToDb()
    }
    println("--------------")
    println("Both houldn't have ${removedID}: ")
    println("Boxed Properties before put: " + propertyBox.all.map { it.id })
    println("New Image Properties before put: " + image.properties.map { it.id })

    imageBox.put(image)

    println("--------------")
    println("Should still not have ${removedID}")
    println("Boxed Properties after put: " + propertyBox.all.map { it.id })
    println("New Image Properties after put: " + image.properties.map { it.id })
    }

@Entity
data class Image(
    @Id
    var id: Long = 0,
   ....
) {
    @Backlink(to = "image")
    lateinit var properties: ToMany<Property>
}

@Entity
data class Property(
    @Id
    var id: Long = 0,
   ..
) {
    lateinit var image: ToOne<Image>
}

Additional context
Flipping the order (e.g. first removing the entity from the box) and THEN removing it from the ToMany works.

Contributor guide

No contributing guide indexed for this repository

First steps

  1. Read the whole issue, then the project's contributing guide.
  2. Comment on the issue to say you are picking it up — it saves two people doing the same work.
  3. Fork the repository and make your change on a branch.
  4. Open a pull request that references the issue number.

Research direction

Start with the Kotlin reproduction and app/src/main/java/com/mobilecomputing/collit/data/datasource/LocalImageDataSource.kt, focusing on ToMany.removeById, applyChangesToDb, and Box.put. Reproduce both removal orders and trace the relationship update. Done means the deleted Property does not reappear after putting the parent, regardless of operation order.

Written by the indexing model from the issue text.

Assessment

Tech stack
android, kotlin
Domain
database, mobile
Issue type
Bug
Difficulty
4/5
Estimated time
3-5 days
Activity status
Stale
Clarity
Mostly clear
Newbie friendliness
35/100

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