I have such MongoDB Collection:
{
date: date,
domain: domain,
visitors: [ {owner:owner, ip:ip, views:views} ]
}
Now I want to check where date equals date AND domain equals domain it should delete the whole visitors array, e.g.:
collection.update({"date":date, {"domain":domain} {"$pull":{"visitors"}} )
How to make this work?
You could try use the $set operator to empty the visitors array instead of removing all items by using the $pull operator, which would be much faster as the $pull will have to do calculations on arrays:
db.collection.update( {"date": date, "domain": domain}, { $set : {"visitors": [] }} , {multi: true} )
The equivalent $pull operation would be
db.collection.update( {"date": date, "domain": domain}, { $pull : { "visitors": {} }}, {multi: true} )
$pull : { "visitors": {} } does not work for me.db.test.update({"$and": [{date:"date"}, {domain:"domain"}]}, {"$set":{visitors:[]}})
You should use the $and operator to match your update query.
Removing all Elements from the Array is the same as setting the value of visitors to the empty array [ ]. But setting it to the empty array is quicker and easier to write and understand, so you should use this.
$and isn't needed here as multiple query terms are implicitly ANDed already. Just use {date: date, domain: domain}.$and in the first place if you change your query later it is easier to update and understand.$and has prevented the query optimizer from using the "right" index, so I've learned to only use it when actually needed.