Store Map values as Long instead of Int

[alghe-global]

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Is there an existing issue?

• [x] I have searched existing issues

Use case

I am storing a mapping:

val mapping = mutableMapOf(
    "key1" to mutableMapOf(
        "subkey1" to 1L,
        "subkey2" to 1L,
        "subkey3" to 1L
    ),
   "key2" to 1L

that is represented in the data class as follows:

@Entity
data class MyDataClass(
    @Id var id: Long = 0,
    var mapping: MutableMap<String, Any>? = null

ObjectBox will store the Long values as Ints due to not being wide enough. These breaks use cases where we do want to store the Long values as Long and not as Ints (for example test cases that use the same generated mock data to store in the database and to test against).

Proposed solution

Have an annotation that tells ObjectBox to store Long values as Long.

Alternatives

Tried using a PropertyConverter however this breaks for the mapping I've provided.

Additional context

Kotlin Android

[alghe-global]

Tried to workaround it by implementing:

val mapping = mutableMapOf(
    "key1" to mutableMapOf(
        "subkey1" to 1L,
        "subkey2" to 1L,
        "subkey3" to 1L
    ),
    "key2" to mutableMapOf(
        "subkey4" to 1L
    )
)

and

@Entity
data class MyDataClass(
    @Id var id: Long = 0,
    var mapping: MutableMap<String, MutableMap<String, Long>? = null
)

however, ObjectBox still stores Long as Integer.

[greenrobot-team]

Thanks for this great issue! This behavior is due to ObjectBox using a FlexObjectConverter subclass by default for these "flex" properties, see their discussion in the docs, notably the converter class documentation.

As you hinted at, try to override this with a specific converter. The built-in StringLongMapConverter should do what you want:

@Convert(converter = StringLongMapConverter::class, dbType = ByteArray::class)
var mapping: MutableMap<String, Any>? = null

Note: labeled this issue with "more info required" so it will auto-close in a few days if there are no follow-up comments.

Edit: also added this as an example in the docs linked above.

[alghe-global]

I've tried

@Convert(converter = StringLongMapConverter::class, dbType = ByteArray::class)
var mapping: MutableMap<String, Any>? = null

however, the retrieved type from the database is still Integer instead of Long.

---

Steps to reproduce

1. Have the entity:

import io.objectbox.annotation.Convert
import io.objectbox.annotation.Id
import io.objectbox.converter.StringLongMapConverter

@Entity
data class MyDataClass(
    @Id var id: Long = 0,
    @Convert(converter = StringLongMapConverter::class, dbType = ByteArray::class)
    var mapping: MutableMap<String, Any>? = null
)

2. Have the mock data generation source:

class MockDataSource {

    fun generateData(): List<MyDataClass> {
        val mappingOne = mutableMapOf(
            "key1" to mutableMapOf(
                "subkey1" to 1L,
                "subkey2" to 1L,
                "subkey3" to 1L
            ),
           "key2" to 1L
        )

        val mappingTwo = mutableMapOf(
            "key1" to mutableMapOf(
                "subkey1" to 2L,
                "subkey2" to 2L,
                "subkey3" to 2L
            ),
           "key2" to 2L
        )

        val mappingThree = mutableMapOf(
            "key1" to mutableMapOf(
                "subkey1" to 3L,
                "subkey2" to 3L,
                "subkey3" to 3L
            ),
           "key2" to 3L
        )

        val mappingsList = listOf(
            MyDataClass(
                mapping = mappingOne
            ),
            MyDataClass(
                mapping = mappingTwo
            ),
            MyDataClass(
                mapping = mappingThree
            )
        )

        return mappingsList
    }
}

3. Test:

fun `test MyDataClass`() {
    val mappingsList = MockDataSource().generateData()

    /** Insert test mappings into the database */
    boxStore.boxFor<MyDataClass>().put(mappingsList)

    <get query from database>

    assertEquals(mappingsList, queryResult)
}

I've left out <get query from database> since in my case it's convoluted (since it's Android with Jetpack Compose, I implement a repository and order based on field timestamp and return a flow - it'll be too long to write it here).

Please note this is with ObjectBox v3.8.0 in Android using Kotlin

[alghe-global]

I've tried the converter using the second layout and it worked.

[alghe-global]

Additionally, what's strange, is that with:

var mapping: MutableMap<String, Long>? = null

ObjectBox will correctly return a Long and not an Integer

[greenrobot-team]

Thanks! Did you by chance debug this and verified that the converter actually restores as Long? E.g. it hits this line: https://github.com/objectbox/objectbox-java/blob/289cc2c29b6c049471a601366615f1bf2ac035eb/objectbox-java/src/main/java/io/objectbox/converter/FlexObjectConverter.java#L290

I'll try to reproduce this once I have time. Maybe this is a Kotlin thing.

[alghe-global]

I've only ran the test with debugger by setting a breakpoint on the assert line and verifying the type of the values returned by the mock data source against the ones returned by the database query call.

[greenrobot-team]

We tried to reproduce this and using the converter I suggested works.

Edit: I also added flex properties to the supported types list with a strong hint to read the documentation about limitations.

Note: labeled this issue with "more info required" so it will auto-close in a few days if there are no follow-up comments.