LessThanDot

In this post we are going to take a look at how to export data into files. We are going to export data in json format as well as in csv format. To get started first connect to mongodb and create a new database named ExportDB

You can just execute the following to create this database

use ExportDB

You should get a message like the following

switched to db ExportDb

Insert these 5 items

db.Person.insert( { name : "Denis",  age : 20, city : "Princeton" } )
db.Person.insert( { name : "Abe",    age : 30, city : "Amsterdam" } )
db.Person.insert( { name : "John",   age : 40, city : "New York"  } )
db.Person.insert( { name : "Xavier", age : 10, city : "Barcelona" } )
db.Person.insert( { name : "Zen",    age : 50, city : "Kyoto"     } )

Now it is time to do the export. To do the export we will use the mongoexport utility, you can find this in the bin directory of your MongoDB install. I my case it is in the C:NoSQLmongodbbin directory. Open up a new command window and cd into the folder where mongoexport is located.

Export in json format

To export the data, we need to tell mongoexport what database to use, what collection to use and optionally we also need to specify what fields to use. If you don’t specify the fields, you will get all of them. If we wanted to export the name and age fields from the Person collection in the ExportDb database, you would specify it like this

mongoexport --db ExportDb --collection Person -fields name,age

Here is the output

C:NoSQLmongodbbin>mongoexport --db ExportDb --collection Person -fields name,age
connected to: 127.0.0.1
{ "_id" : { "$oid" : "510e5da10e0a53ddf5f2865b" }, "name" : "Denis", "age" : 20 }
{ "_id" : { "$oid" : "510e5da20e0a53ddf5f2865c" }, "name" : "Abe", "age" : 30 }
{ "_id" : { "$oid" : "510e5da20e0a53ddf5f2865d" }, "name" : "John", "age" : 40 }
{ "_id" : { "$oid" : "510e5da20e0a53ddf5f2865e" }, "name" : "Xavier", "age" : 10 }
{ "_id" : { "$oid" : "510e5da80e0a53ddf5f2865f" }, "name" : "Zen", "age" : 50 }
exported 5 records

As you can see you got the output in the window. What about a file? You can use -o with the filename to redirect output into a file, all we are adding is -o Person.txt to the previous command

mongoexport --db ExportDb --collection Person  -fields name,age -o Person.txt

Here is the output

C:NoSQLmongodbbin>mongoexport --db ExportDb --collection Person  -fields name,age -o Person.txt
connected to: 127.0.0.1
exported 5 records

C:NoSQLmongodbbin>

If you now locate the file in the bin directory and open the file, you should see something like this

Export in csv format

Exporting in csv format is pretty much the same as before with the addition of –csv. Our command will look like this

mongoexport --db ExportDb --collection Person --csv -fields name,age

Here is the output

C:NoSQLmongodbbin>mongoexport --db ExportDb --collection Person --csv -fields name,age
connected to: 127.0.0.1
name,age
"Denis",20.0
"Abe",30.0
"John",40.0
"Xavier",10.0
"Zen",50.0
exported 5 records

C:NoSQLmongodbbin>

Just like before we want to direct the output into a file instead of onto the screen, we will just add -o Person.csv to the command , the command will look like this

mongoexport –db ExportDb –collection Person –csv -fields name,age -o Person.csv

C:NoSQLmongodbbin>mongoexport --db ExportDb --collection Person --csv -fields name,age -o Person.csv
connected to: 127.0.0.1
exported 5 records

C:NoSQLmongodbbin>

Now if we open up the file in notepad you will see the following