CODEWITHSUNDEEP
mongodb
user5854440
user5854440

Reputation: 281

MongoDB: $elemMatch

I'm trying to use $elemMatch to find an object in an array. I imported the following data into a collection named trails:

{ "Copper" : [
        {"name" : "Spaulding Bowl", "level" : "Extreme Terain", "location" : "East Side"},
        {"name" : "Resolution Bowl", "level" : "Double Black", "location" : "East Side"},
        {"name" : "Black Bear Glade", "level" : "Double Black", "location" : "East Side"},
        {"name" : "Free Fall Glade", "level" : "Double Black", "location" : "East Side"}
 ]
}

I'm using the syntax from the MongoDB documentation to make the following query:

db.trails.find( { "Copper": { $elemMatch: { "name" : "Spaulding Bowl" } }  } )

I have also tried formating it without quotations around the keys:

db.trails.find( { Copper: { $elemMatch: { name : "Spaulding Bowl" } }  } )

Instead of returning just one matching element, both return the entire array of objects. Is there a syntax error I'm missing? All tips are appreciated.

Upvotes: 1

Views: 337

Answers (1)

s7vr
s7vr

Reputation: 76004

$elemmatch(query) returns all rows in a array when there is atleast one row matching the query criteria.

$elemMatch(projection) returns only the first row of all the matching rows when used as projection.

You don't need elemMatch for your case as it is only single criteria.

db.trails.find({"Copper.name": { "Spaulding Bowl" } })

Try as below which uses the elemMatch projection variation. 

db.trails.find({}, {"Copper": { $elemMatch: { "name" : "Spaulding Bowl" } }  } )

Upvotes: 2

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