Querying array elements with Mongo

问题

How can I query the smoothies that have apple in them? (below is a collection with 3 documents)

_id => 1
name => 'best smoothie' 
ingredients => Array
    (
        [0] => apple
        [1] => raspberry
        [2] => orange
        [3] => banana
    )
_id => 2
name => 'summer smoothie' 
ingredients => Array
    (
        [0] => lemon
        [1] => mint

    )
_id => 3
name => 'yogurt smoothie' 
ingredients => Array
    (
        [0] => apple
        [1] => blueberry

    )

回答1:

If you simply run the below query MongoDB is smart enough to figure out what you're trying to do.

{ ingredients: "apple" }

Mongo will see that ingredients is a list and only return documents that contain "apple" some where in that list.

回答2:

From the documentation:

Note: Fields containing arrays match conditional operators, if only one item matches.

Therefore, the following query:

db.collection.find( { field: { $gt:0, $lt:2 } } );

Will match a document that contains the following field:

{ field: [-1,3] }

回答3:

Why do people write scalable applications for smoothies?

db.find({"ingredients":{$in: "apple"}});

来源：https://stackoverflow.com/questions/3308119/querying-array-elements-with-mongo