Deleting a single object from an array of objects in MongoDB
mongodb
Solution
You were close. The query should be like this:
db.test.update({"city":"Palo Alto"},{"$pull":{"friends":{"name":"Frank"}}});
`$pull` takes an object whose field specifies the field array `"friends"`. The value `{"name":"Frank"}` represents the query (to run inside the array) to find the element to pull out.
Problem
Say we have the following collection of documents: ``` { "_id" : ObjectId("50a69fa904c8310609600be3"), "id" : 100, "city" : "San Francisco", "friends" : [ { "id" : 1, "name" : "John" }, { "id" : 2, "name" : "Betty" }, { "id" : 3, "name" : "Harry" } ] } { "_id" : ObjectId("50a69fc104c8310609600be4"), "id" : 200, "city" : "Palo Alto", "friends" : [ { "id" : 1, "name" : "Carol" }, { "id" : 2, "name" : "Frank" }, { "id" : 3, "name" : "Norman" } ] } { "_id" : ObjectId("50a69fc304c8310609600be5"), "id" : 300, "city" : "Los Angeles", "friends" : [ { "id" : 1, "name" : "Fred" }, { "id" : 2, "name" : "Neal" }, { "id" : 3, "name" : "David" } ] } . . . ``` Now let's say that Frank (Palo Alto, id=2) is no longer my friend, and I want to delete him from the collection. I thought the following might work, but it doesn't: ``` db.test.update({"city":"Palo Alto"},{"$pull":{"friends.name":"Frank"}}) ``` I'd like to be able to do something like that. Delete an object within an array within a collection of documents. How do you do this?