How to use JaVers with Map?

Question

I have two maps that can be modified by different authors. In this particular use case, I have a limitation where I shouldn't use POJOs or Domain objects, only a Maps.

    @Test
    fun `Shadow from a map`() {
        val javers = JaversBuilder.javers().build()
        val exercise = mutableMapOf("_id" to "1", "title" to "my exercise", "starred" to false)
        javers.commit("bob", exercise)
        
        exercise["starred"] = true
        javers.commit("bob", exercise)
        
        exercise["title"] = "my great exercise"
        exercise["starred"] = true
        javers.commit("alice", exercise)

        val training = mutableMapOf("_id" to "2", "title" to "my training")
        javers.commit("alice", training)
        
        training["title"] = "my great training"
        javers.commit("jack", training)


        val query: JqlQuery = QueryBuilder.byInstance(exercise).build()
        val shadows: List<Shadow<Map<*,*>>> = javers.findShadows(query)
        assertThat(shadows.size, `is`(3))
    }

The test execution displays the following error:

MALFORMED_JQL: Invalid JQL query, object passed to byInstance(Object) query should be instance of Entity or ValueObject, got MapType{ baseType: 'class java.util.LinkedHashMap' } - '{_id=1, title=my great exercise, starred=true}'.
Did you mean byInstanceId(Object localId, Class entityClass)?
JaversException MALFORMED_JQL: Invalid JQL query, object passed to byInstance(Object) query should be instance of Entity or ValueObject, got MapType{ baseType: 'class java.util.LinkedHashMap' } - '{_id=1, title=my great exercise, starred=true}'.
Did you mean byInstanceId(Object localId, Class entityClass)?
    at org.javers.repository.jql.FilterDefinition$InstanceFilterDefinition.compile(FilterDefinition.java:91)
    at org.javers.repository.jql.JqlQuery.compile(JqlQuery.java:129)
    at org.javers.repository.jql.QueryCompiler.compile(QueryCompiler.java:19)
    at org.javers.repository.jql.ShadowStreamQueryRunner$StreamQuery.<init>(ShadowStreamQueryRunner.java:59)
    at org.javers.repository.jql.ShadowStreamQueryRunner.queryForShadowsStream(ShadowStreamQueryRunner.java:34)
    at org.javers.repository.jql.QueryRunner.queryForShadowsStream(QueryRunner.java:32)
    at org.javers.core.JaversCore.findShadowsAndStream(JaversCore.java:194)
    at org.javers.core.JaversCore.findShadows(JaversCore.java:188)

How should I build the JqlQuery to find the shadows?

Answer 1

You can compare two top level Maps but you cant commit a map to Javers Repository (exception should be thrown) because Maps have no identifiers.