问题
I have created an index with unique=true on one of the fields in my Mongo document. This works as expected - it disallows duplicates by overwriting the existing entry.
I would like to disallow overwrites, and instead get an error or exception when an attempt is made to insert a duplicate. Is there any way to do this? How would I do this with Spring Data MongoDB?
回答1:
By adding WriteConcern=SAFE to the MongoTemplate configuration, I was able to get exceptions when the "unique=true" constraint is violated. I handle the exception and disallow overwrites.
回答2:
The indexed annotation has a parameter dropDups=true which would give you what you want.
Indexed (unique=true, dropDups=true)
http://static.springsource.org/spring-data/data-mongodb/docs/1.1.0.RELEASE/api/org/springframework/data/mongodb/core/index/Indexed.html
来源：https://stackoverflow.com/questions/14033272/mongodb-unique-indexes-disallow-overwrite