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if object referenced from generic collection dumping may erase tags and prevent future loading #82

Closed GoogleCodeExporter closed 9 years ago

GoogleCodeExporter commented 9 years ago 
Assume Java Bean has some property of type Collection<SomeRealClass> and this 
collection has object referenced from some where else in the Object-Tree we are 
going to dump.

Depending on the Object-Tree and order of dumping resulting dump may fail 
during load.
It will happen because of erased tags.

Original issue reported on code.google.com by alexande...@gmail.com on 1 Sep 2010 at 2:03

GoogleCodeExporter commented 9 years ago 
see example 
http://code.google.com/p/snakeyaml/source/detail?r=96cd1acce41722c056e582270aee1
47bd16cac9c

Original comment by alexande...@gmail.com on 1 Sep 2010 at 2:10

GoogleCodeExporter commented 9 years ago 
I see that GeneralAccount does not get a tag because its class is the same as 
specified in the collection.
Loader does not see that GeneralAccount is not a map (with 'name' key) but a 
JavaBean with 'name' property.

Original comment by py4fun@gmail.com on 1 Sep 2010 at 5:13

GoogleCodeExporter commented 9 years ago 
SuperSaverAccount is dumped with name=General instead of proper SuperSaver

Original comment by py4fun@gmail.com on 1 Sep 2010 at 5:27

GoogleCodeExporter commented 9 years ago 
Shame on me - I forgot to change package name..... sorry 
Thx for the fix. 

Have not noticed the name thing. Actually nice that it came out.
I might have an idea why ;) I think it would he nice to formalize it as a 
separate issue.

Back to aliased thing... 
You are right. Tag "erased" when Collection<GeneralAccount> serialized.
But when Collection<Account> property name starts with 'a' it is dumped and as 
a result loaded first.
So loader can not guess the real class for the provided map... Loading fails. 
It might be even more fun when you change type Collection<Account> to 
Collection or Collection<?>. During loading that Collection will containe not 
only Account but Map also. Loading most probably will fail anyway when 
Collection<GeneralAccount> is composed.

But when we give name for the Collection<GeneralAccount> starting with 'a' and 
for the Collection<Account> starting with 'b. First Collection<GeneralAccount> 
serialized. Loading will be successful. It is because missing tag will be 
substituted with determined class. Created object then will be added to 
Collection<Account> without any problem since GeneralAccount implements Account.

I think in first case tag should not be erased. I have a solution, but still 
checking if more general changes could be done to fix it.

Hope the explanation is not too messy ;)

Original comment by alexande...@gmail.com on 1 Sep 2010 at 8:54

GoogleCodeExporter commented 9 years ago 
Seems like even if GeneralAccount has associated CustomTag same thing happens - 
it is erased.

Original comment by alexande...@gmail.com on 2 Sep 2010 at 8:39

GoogleCodeExporter commented 9 years ago 
This issue was closed by revision 1af98fbf8c.

Original comment by alexande...@gmail.com on 6 Sep 2010 at 1:35