mongoexport and mongoimport

While mongodump/mongorestore work with MongoDB's native .bson format, mongoexport/mongoimport work with plain JSON and CSV — formats you can open in a text editor or spreadsheet.

Exporting to JSON

mongoexport --db rahultechnology --collection employees --out emp11.json
mongoexport --db rahultechnology --collection employees --out /home/rahul/Music/emp.json

Export only a limited number of records:

mongoexport --db rahultechnology --collection employees --limit 2 --out emp11.json

Export only specific fields:

mongoexport --db rahultechnology --collection employees --fields empid,name --out emp11.json

Exporting to CSV

Add --type=csv and the export otherwise works the same way:

mongoexport --db rahultechnology --collection employees --type=csv --out emp11.csv

mongoexport --db rahultechnology --collection employees --limit 2 --type=csv --out emp11.csv

mongoexport --db rahultechnology --collection employees --type=csv --fields empid,name --out emp11.csv

Importing JSON or CSV

mongoimport --db rahultechnology --collection emp1111 --type=json --file ./emp.json

mongoimport --db rahultechnology --collection emp1115 --type csv --file emp11.csv --headerline

--headerline tells mongoimport that the first row of the CSV contains column names, rather than data — without it, MongoDB would insert that header row as a document.

Common Errors & Troubleshooting

• CSV import inserting the header row as a document — always pass --headerline when the first row of your CSV is column names, not real data.
• mongoimport failing on nested/array fields in CSV — CSV is inherently flat; nested objects and arrays don't translate cleanly to CSV rows. Use JSON for anything beyond simple flat documents.
• Field type guessing going wrong — mongoimport's CSV mode infers types automatically by default, which can turn something like a leading-zero ZIP code into a number, dropping the zero. Use --columnsHaveTypes to specify types explicitly when this matters.

Key Takeaways

• mongoexport/mongoimport deal in human-readable JSON/CSV, unlike the binary .bson used by mongodump/mongorestore.
• --limit and --fields let you export a subset of rows or columns instead of the whole collection.
• Always add --headerline when importing a CSV that has column names in its first row.