EnsureIndexes() fails when my Entity contains Embedded List<HashMap<K, V>>

[fedjo]

Hello,

I have a class (ket's say MyClass.java) annotated with @Entity with has a field of type List<HashMap<K, V>> field_1 annotated with @Embedded.

I can store documents in a proper way as list of DBObjects eg:

[{ .... }, { ... }, {},... ]

but when I'm running Datastore's method
ensureIndexes(MyClass.class) I get the following exception,

java.lang.ClassCastException: sun.reflect.generics.reflectiveObjects.ParameterizedTypeImpl cannot be cast to java.lang.Class at org.mongodb.morphia.mapping.MappedField.discoverType(MappedField.java:199) ~[morphia-1.0.1.jar:na] at org.mongodb.morphia.mapping.MappedField.discover(MappedField.java:117) ~[morphia-1.0.1.jar:na] at org.mongodb.morphia.mapping.MappedField.<init>(MappedField.java:95) ~[morphia-1.0.1.jar:na] at org.mongodb.morphia.mapping.MappedClass.discover(MappedClass.java:214) ~[morphia-1.0.1.jar:na] at org.mongodb.morphia.mapping.MappedClass.<init>(MappedClass.java:145) ~[morphia-1.0.1.jar:na]

As you can understand I use morphia version 1.0.1.
I have tried with 1.1.1 having the same exception, and with 0.111 I couldn't compile my code!

[evanchooly]

can you post your entity source?

[fedjo]

The indexes annotations are

@Indexes({
        @Index(fields = @Field(value = "resourceType", type = IndexType.ASC), options = @IndexOptions()),
        @Index(fields = @Field(value = "administrative.withCreator", type = IndexType.ASC), options = @IndexOptions()),\
        @Index(fields = @Field(value = "administrative.externalId", type = IndexType.ASC), options = @IndexOptions()),
        @Index(fields = @Field(value = "provenance.provider", type = IndexType.ASC), options = @IndexOptions()),
        @Index(fields = @Field(value = "provenance.resourceId", type = IndexType.ASC), options = @IndexOptions()),
        @Index(fields = @Field(value = "descriptiveData.label", type = IndexType.ASC), options = @IndexOptions()),
        @Index(fields = @Field(value = "collectedIn", type = IndexType.ASC), options = @IndexOptions()) })

and the field which creates the problem is

@Embedded
private List<HashMap<MediaVersion, EmbeddedMediaObject>> media;

Because the full entity was to big I pasted it on that link

[http://pastebin.com/KNUa1VcR]

thanks again,
@evanchooly

[evanchooly]

Great, thanks. I'll try to play with this today and see what shakes out.

[evanchooly]

I had to massage the code a little to get things to compile/resolve properly (because I don't have your entire model which is fine-ish) and i get a different error. "Generic TypeVariable not supported" which is more in keeping with what I expected to see since Morphia has issues mapping unbound type parameters. I don't suppose you can put together a complete test case and zip it up somewhere?

[fedjo]

Sorry for being late :-P
Compile it and run it should give the following error:

Exception in thread "main" java.lang.ClassCastException: sun.reflect.generics.reflectiveObjects.ParameterizedTypeImpl cannot be cast to java.lang.Class

morphiaBug.zip

[evanchooly]

Looking in to this, I see where the problem is and even have a good grasp on what the fix is. Sadly, it duplicates a lot of the work targeted for 2.0(ish) which includes a rewrite of the mapping code. I'm not quite ready, yet, to say "just wait for 2.0" because that's not a great answer but I'm mulling my options here. I'd rather not go through the work of (re)fixing this code only to throw it away in a (hopefully) few months.

[fedjo]

I totally agree @evanchooly .

Otherway or not we have managed to overcome this problem by indexing the field we want manually.
So I will wait for version 2.0.

PS: Could you give me a hint about the bug or the code in order to try to understand how the mapping system of Morphia works?
I would really like to patch morphia by myself!

[evanchooly]

It has to do with how morphia is discovering and tracking generic types. The code is rather gnarly which is why it's being replaced. MappedField and EphemeralMappedField (terrible name even though I chose it) are the guts of where the failure lies.

[cmoetzing]

"just wait for 2.0"

For me that is fine. The described workaround from #921 is just a few lines long and therefore does not hurt. I'm happy to remove it when 2.0 arrives. ;-)

[evanchooly]

This appears to work on 2.0. I'm going to revive the 2.0.0-SNAPSHOT publishing (it normally happens automatically with every commit but some quality checks are fading.) If you feel up for testing it against 2.0 (even in a test project), I'd love the feedback.

[evanchooly]

snapshot builds are pushing again and should be regularly updated after each build should you want to give them a try.