How to Use mongoexport: Export MongoDB Data Easily

Use mongoexport to export data from a MongoDB collection to a JSON or CSV file. The basic command includes specifying the database, collection, and output file with options like --db, --collection, and --out.

Syntax

The basic syntax of mongoexport is:

• --db: The database name to export from.
• --collection: The collection name to export.
• --out: The file path to save the exported data.
• --jsonArray: (Optional) Export data as a JSON array.
• --type: (Optional) Specify output format: json (default) or csv.
• --fields: (Optional) For CSV, specify which fields to export.

bash

mongoexport --db=<database> --collection=<collection> --out=<file> [--jsonArray] [--type=csv] [--fields=field1,field2]

Example

This example exports the users collection from the mydb database to a JSON file named users.json. It uses --jsonArray to export the data as a JSON array.

bash

mongoexport --db=mydb --collection=users --out=users.json --jsonArray

Output

[
  {
    "_id": {"$oid": "507f1f77bcf86cd799439011"},
    "name": "Alice",
    "age": 30
  },
  {
    "_id": {"$oid": "507f1f77bcf86cd799439012"},
    "name": "Bob",
    "age": 25
  }
]

Common Pitfalls

Common mistakes when using mongoexport include:

• Not specifying the correct database or collection name, resulting in no data exported.
• For CSV exports, forgetting to specify --fields, which causes an error.
• Using --out without write permission to the target directory.
• Not using --jsonArray when you want a valid JSON array output.

bash

Wrong:
mongoexport --db=mydb --collection=users --type=csv --out=users.csv

Right:
mongoexport --db=mydb --collection=users --type=csv --fields=name,age --out=users.csv

Quick Reference

Option	Description
--db	Specify the database name
--collection	Specify the collection name
--out	File path to save exported data
--jsonArray	Export data as a JSON array
--type	Output format: json (default) or csv
--fields	Comma-separated list of fields for CSV export

Key Takeaways

Use --db and --collection to specify the source data.

Always specify --out to save the exported file.

Use --jsonArray for valid JSON array output.

For CSV exports, include --fields to list columns.

Check file permissions to avoid write errors.