I have a MongoDB collection with documents in the following format:
{
"_id" : ObjectId("4e8ae86d08101908e1000001"),
"name" : ["Name"],
"zipcode" : ["2223"]
}
{
"_id" : ObjectId("4e8ae86d08101908e1000002"),
"name" : ["Another ", "Name"],
"zipcode" : ["2224"]
}
I can currently get documents that match a specific array size:
db.accommodations.find({ name : { $size : 2 }})
This correctly returns the documents with 2 elements in the name
array. However, I can't do a $gt
command to return all documents where the name
field has an array size of greater than 2:
db.accommodations.find({ name : { $size: { $gt : 1 } }})
How can I select all documents with a name
array of a size greater than one (preferably without having to modify the current data structure)?
There's a more efficient way to do this in MongoDB 2.2+ now that you can use numeric array indexes in query object keys.
// Find all docs that have at least two name array elements.
db.accommodations.find({'name.1': {$exists: true}})
You can support this query with an index that uses a partial filter expression (requires 3.2+):
// index for at least two name array elements
db.accommodations.createIndex(
{'name.1': 1},
{partialFilterExpression: {'name.1': {$exists: true}}}
);