How to create query with ObjectIds using java?

java, mongodb, mongodb-java

Solution

`{ "$oid" : "51eae100c2e6b6c222ec3431"}` is the same as `ObjectId("51eae100c2e6b6c222ec3431")` just in a different format.

See this page for the different formats: http://docs.mongodb.org/manual/reference/mongodb-extended-json/

If the query is not finding any documents (and you are sure they are present in the collection) then there is some other issue. I would double check the server(s) you are connecting to and the name of the database and collection first.

Rob.

Problem

I have set of ids like: ``` ["51eae104c2e6b6c222ec3432", "51eae104c2e6b6c222ec3432", "51eae104c2e6b6c222ec3432"] ``` I need to find all documents using this set of ids. ``` BasicDBObject query = new BasicDBObject(); BasicDBList list = new BasicDBList(); ObjectId ob1 = new ObjectId("51eae100c2e6b6c222ec3431"); ObjectId ob2 = new ObjectId("51eae100c2e6b6c222ec3432"); list.add(ob1); list.add(ob2); query.append("_id", new BasicDBObject("$in", list)); ``` This query can't find anything because it is same as ``` { "_id" : { "$in" : [ { "$oid" : "51eae100c2e6b6c222ec3431"} , { "$oid" : "51eae100c2e6b6c222ec3432"}]}} ``` To find something it must be ``` {_id:{$in:[ObjectId("51eae100c2e6b6c222ec3431") , ObjectId("51eae104c2e6b6c222ec3432")]}} ``` but I don't know how to make `ObjectId("51eae100c2e6b6c222ec3431")` in list using java

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