如果Mongoose数组中包含元素，则查找Mongodb文档

Question

If I have a field in a mongodb document which has an array, for example:

"tags" : [  "tag", "etc1",  "etc2",  "etc3" ]

Is there a way that I can select that document if it contains the element 'etc1'?
If I try using the query:

db.coll.find({"tags" : { $elemMatch: { value0: 'etc1'} }})

but I need to know the position of the element in the array, which I don't know.
I have also tried:

db.coll.find({"tags" : { $elemMatch: 'etc1' }})

but it needs to be an object. Is there any way of doing this?

NB I am using mongoose but I wasn't sure how to construct the query

Answer 1

Use the $in operator as described in this question or this other question and as described in the mongodb docs and can be accessed in mongoose .

With it, you'll have a query that looks something like this... remembering that you must pass an array when using $in :

db.coll.find({"tags" : { $in : ['etc1'] } } );

Answer 2

除了使用$ in运算符，您还可以使用$ all运算符，例如：

db.col1.find({"tags":{$all :["etc1"]}})