Query by array of ObjectIds

Question

I have an array of ObjectIDs, representing _id values for documents in a collection:

ObjectID[] documentsAffected

How can I prepare a query to return all the documents that are referenced in this array?

I have looked at the following but it only works with individual values, not arrays:

Query.EQ("_id", documentsAffected)

I don't want to write a for loop and have to return one document at a time either, because I then need to update these documents in the same way and this seems inefficient when I could update them all in one statement after retrieving them all.

Is there a way to effectively do this? If not, is there another way to return all documents based on some list of items that reference them?

i3arnon · Accepted Answer · 2014-10-27 13:53:05Z

1

You can use In instead of EQ:

Query.In("_id", documentsAffected);

Or better off, using the typed options:

Query<Document>.In(doc => doc.Id, documentsAffected);

This will create a query using the $in operator:

The $in operator selects the documents where the value of a field equals any value in the specified array. If the field holds an array, then the $in operator selects the documents whose field holds an array that contains at least one element that matches a value in the specified array

From $in

edited Oct 27, 2014 at 13:53

answered Oct 27, 2014 at 13:37

i3arnon

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1 Comment

Augustin Popa Over a year ago

Thanks! I ended up using the second option you specified.

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