Code Summary: MongoDB Shell Tips and Tricks

The following sections explain some tips and tricks for using mongosh.

Use Node.js APIs to Read and Write Files

mongosh provides access to all native Node.js APIs, including the file system module, or fs. This means that you can use mongosh to read and write files. In the following example, we assign the result of a query to a variable called customers so that it can be used later:

const customers = db.sales.find({}, {customer: 1, _id: 0})

Next, we use the fs module to write the results of the query to a file called customers.json. To do this, we pass in the customers variable and use the EJSON.stringify() method to convert the array to a string. We also use the null and 2 parameters to format the output so that it’s easier to read:

fs.writeFileSync('customers.json', EJSON.stringify(customers.toArray()), null, 2)

Generate Seed Data

You can also use npm packages in mongosh, as they support external scripts and require statements. In the following example, we use the faker package to generate an array of 10 fake users. We then insert the users as documents into a new database.

const { faker } = require("@faker-js/faker");
const users = [];
for (let i = 0; i < 10; i++) {
 users.push({
   name: faker.person.fullName(),
   email: faker.internet.email(),
   phone: faker.phone.number(),
 });
}

console.log("Inserting fake users ...");
db.getSiblingDB("test_data").users.insertMany(users);

Note: To use the faker package, you must first install it by using npm install @faker-js/faker --save-dev in the same directory as your external script. Or, you can install the package globally by using npm install -g @faker-js/faker.