You could use a regex. In your example that would be: db.stuff.find( { foo: /^bar$/i } ); I must say, though, maybe you could just downcase (or upcase) the value on the way in rather than incurring the extra cost every time you find it. Obviously this wont work for people’s names and such, but … Read more
Not strange at all, people do this all the time. Make sure the collection name is correct (case matters) and that the ObjectId is exact. Documentation is here > db.test.insert({x: 1}) > db.test.find() // no criteria { “_id” : ObjectId(“4ecc05e55dd98a436ddcc47c”), “x” : 1 } > db.test.find({“_id” : ObjectId(“4ecc05e55dd98a436ddcc47c”)}) // explicit { “_id” : ObjectId(“4ecc05e55dd98a436ddcc47c”), “x” … Read more
Starting with the 3.2 release of MongoDB, you can get N random docs from a collection using the $sample aggregation pipeline operator: // Get one random document from the mycoll collection. db.mycoll.aggregate([{ $sample: { size: 1 } }]) If you want to select the random document(s) from a filtered subset of the collection, prepend a … Read more
For lazy people, use mongodump, it’s faster: mongodump -d <database_name> -o <directory_backup> And to “restore/import” it (from directory_backup/dump/): mongorestore -d <database_name> <directory_backup> This way, you don’t need to deal with all collections individually. Just specify the database. Note that I would recommend against using mongodump/mongorestore for big data storages. It is very slow and once … Read more
Try this: If your collection was ‘example’ db.example.update({}, {$unset: {words:1}}, false, true); Refer this: http://www.mongodb.org/display/DOCS/Updating#Updating-%24unset UPDATE: The above link no longer covers ‘$unset’ing. Be sure to add {multi: true} if you want to remove this field from all of the documents in the collection; otherwise, it will only remove it from the first document it … Read more
Same as the updating existing collection field, $set will add a new fields if the specified field does not exist. Check out this example: > db.foo.find() > db.foo.insert({“test”:”a”}) > db.foo.find() { “_id” : ObjectId(“4e93037bbf6f1dd3a0a9541a”), “test” : “a” } > item = db.foo.findOne() { “_id” : ObjectId(“4e93037bbf6f1dd3a0a9541a”), “test” : “a” } > db.foo.update({“_id” :ObjectId(“4e93037bbf6f1dd3a0a9541a”) },{$set : … Read more
MongoDB 2.2’s new $elemMatch projection operator provides another way to alter the returned document to contain only the first matched shapes element: db.test.find( {“shapes.color”: “red”}, {_id: 0, shapes: {$elemMatch: {color: “red”}}}); Returns: {“shapes” : [{“shape”: “circle”, “color”: “red”}]} In 2.2 you can also do this using the $ projection operator, where the $ in a … Read more
You can also evaluate a command using the –eval flag, if it is just a single command. mongo –eval “printjson(db.serverStatus())” Please note: if you are using Mongo operators, starting with a $ sign, you’ll want to surround the eval argument in single quotes to keep the shell from evaluating the operator as an environment variable: … Read more
The best way to do this is in version 4.2+ which allows using the aggregation pipeline in the update document and the updateOne, updateMany, or update(deprecated in most if not all languages drivers) collection methods. MongoDB 4.2+ Version 4.2 also introduced the $set pipeline stage operator, which is an alias for $addFields. I will use … Read more
In the mongo shell: use [database]; db.dropDatabase(); And to remove the users: db.dropAllUsers();