Echo Echo - 3 months ago 15
Java Question

Remove an entry from array using MongoDB-Java driver

I have JSON like :

{ "_id" : "1", "_class" : "com.model.Test", "itemList" : [ { "itemID" : "1", "itemName" : "Foo", "resources" : [ { "resourceID" : "1", "resourceName" : "Foo Test1", }, { "resourceID" : "2", "resourceName" : "Foo Test2", } ] } ] }


I need to be able to remove one of records of itemList.
I have done the following:

public void removeItemByID(String docID, String itemID) throws Exception {
MongoOperations mongoOperations = mongoConfiguration.getMongoTemplate();
Query query = new Query(where("_id").is(docID).and("itemList.itemID").is(itemID));
mongoOperations.remove(query, Item.class);
}


This approach doesn't work.
However when I have used the BasicDBObject with $pull approach it works fine !
What's the difference among these approaches !

Answer

If you want to remove an array generally I use the following:

BasicDBObject match = new BasicDBObject("_id", "1"); // to match your document
BasicDBObject update = new BasicDBObject("itemList", new BasicDBObject("itemID", "1"));
coll.update(match, new BasicDBObject("$pull", update));
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