GENERIC_TYPE_NOT_PARAMETRIZED

[ctmay4]

This is probably a lack of understanding on my part, but I am getting this error trying to commit changes to the repository:

JaversException: GENERIC_TYPE_NOT_PARAMETRIZED JaVers runtime error - expected actual Class arguments in type 'java.util.List<java.util.List<java.lang.String>>'. Javers needs to know what kind of content is stored in your collections. Try at least <Object>

It doesn't seem to like the fact that I have a field that is a List<List>. The field in question looks like this (that is a Morphia annotation):

@Property("rows")
private List<List<String>> _rows;

and the getter/setter look like this (that is a Jackson annotation):

@JsonProperty("rows")
public List<List<String>> getRawRows() {
    return _rows;
}

public void setRawRows(List<List<String>> rows) {
    _rows = rows;
}

Do I have to register that property when I create my javers instance? Here is how I build it:

_javers = JaversBuilder.javers()
        .registerValueGsonTypeAdapter(ObjectId.class, new ObjectIdAdapter())
        .withMappingStyle(MappingStyle.BEAN)
        .registerEntity(StagingSchema.class, "internalId")
        .registerEntity(StagingTable.class, "internalId")
        .registerJaversRepository(new MongoRepository(getDatastore().getDB()))
        .build();

I looked in the documentation but only saw property configuration for ignoring a field or setting a field to be an identifier.

[bartoszwalacik]

yeah, looks like that error message is not very informative in this case. I'll change this message.

But te be honest, List<List<String>> is not what we can support for now.
Not sure how we could model a Change for this type.

Are you able to change this data model, and introduce a new ValueObject class?
Or is it required by some framework you use?

For example to sth like this

private List rows_;

public class StringList {
private List strings;
}

[ctmay4]

I might be able to change it, but it is going to be alot of work. There are alot of things that already use it. Why is it easier to support a List where sub-class only has a List vs just having a List<List>?

Is there a way that I could say to ignore it so I could continue my testing?

[bartoszwalacik]

as a quick workaround you can add @DiffIgnore to the field. Give me a while to think out how to solve this problem better

[ctmay4]

Any more thoughts on this? It is the last show stopper for me. The issue is that I want my raw data to look like this:

{
  "rows": [
    ["A", "1"],
    ["B", "2"],
    ["C", "3"]
   ]
}

Since I use Jackson, the entity is annotated like this:

    @Property("rows")
    private List<List<String>> _rows;

I could change the entity to look like this, which I think would work with your library:

    @Property("rows")
    private List<TableRow> _rows;

and define TableRow as an entity with a single property, which is a List. However then the output would look like this:

{
  "rows": [
    { "row": ["A", "1"] },
    { "row": ["B", "2"] },
    { "row": ["C", "3"] }
   ]
}

which is not my preference.

[bartoszwalacik]

Hi Chuck,
in the new version we have Custom Comparators.
see http://javers.org/javadoc_1.0.0/org/javers/core/JaversBuilder.html#registerCustomComparator-org.javers.core.diff.custom.CustomPropertyComparator-java.lang.Class-
Also we have Custom Json Serializers.
see http://javers.org/documentation/repository-examples/#json-type-adapter

you can use them for a TableRow class

You mean output from Diff serialization or Snapshot from Mongo?

Maybe you can come up with some working example on github, which would describe your case.
It would be easier for me to help you and decide if this only the matter of configuration or does we need a new feature

regards

[ctmay4]

I'm not sure how those would work, but it sounds like they would all involve me changing my entity from looking like this:

    @Property("rows")
    private List<List<String>> _rows;

to this:

    @Property("rows")
    private List<TableRow> _rows;

Which would also change the source JSON of my entities into a format I do not like.

If there is no way to support registering a class to handle the diffs between a List<List> then I may be stuck.

[ctmay4]

I did some more testing and put together a more simple complete example:

https://gist.github.com/ctmay4/df042868def85a380ff8

In that example, I also tested the same object using another library as a point of reference (https://github.com/SQiShER/java-object-diff).

Ideally, there would be a way in JaVers to register how to deal with a List in my example.

Let me know if you need anything else from me.

[bartoszwalacik]

your gist is fine, I'm starting to work on this issue

[bartoszwalacik]

Hi Chuck,
issue is done and available as snapshot version 1.0.5-SNAPSHOT
in sonatype repo: https://oss.sonatype.org/content/repositories/snapshots/

check it and if it works fine, we release it