Built-in roles (read, readWrite, dbAdmin) in MongoDB - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to grant the read role to a user on the database.

MongoDB

db.createUser({user: "reportUser", roles: ["[1]"]})

Drag options to blanks, or click blank then click option'

Aread

BreadWrite

CdbAdmin

Droot

Attempts:

3 left

💡 Hint

Common Mistakes

Choosing readWrite grants write permissions, which is more than needed.

The read role allows the user to read data from the database but not modify it.

2fill in blank

medium

Complete the code to grant the readWrite role to a user on the database.

MongoDB

db.createUser({user: "appUser", roles: ["[1]"]})

Drag options to blanks, or click blank then click option'

Aread

BdbAdmin

CreadWrite

Dbackup

Attempts:

3 left

💡 Hint

Common Mistakes

Choosing read only allows reading, not writing.

The readWrite role allows the user to read and write data on the database.

3fill in blank

hard

Fix the error in the code to grant the dbAdmin role to a user.

MongoDB

db.createUser({user: "adminUser", roles: ["[1]"]})

Drag options to blanks, or click blank then click option'

AdbAdmin

Bread

CreadWrite

DuserAdmin

Attempts:

3 left

💡 Hint

Common Mistakes

Choosing readWrite or read does not provide admin privileges.

The dbAdmin role allows the user to perform administrative tasks on the database, such as creating indexes.

4fill in blank

hard

Fill both blanks to create a user with readWrite and dbAdmin roles.

MongoDB

db.createUser({user: "managerUser", roles: ["[1]", "[2]"]})

Drag options to blanks, or click blank then click option'

AreadWrite

Bread

CdbAdmin

Dbackup

Attempts:

3 left

💡 Hint

Common Mistakes

Using read instead of readWrite limits write access.

The user needs both readWrite to modify data and dbAdmin to manage the database.

5fill in blank

hard

Fill all three blanks to create a user with read, readWrite, and dbAdmin roles.

MongoDB

db.createUser({user: "fullAccessUser", roles: ["[1]", "[2]", "[3]"]})

Drag options to blanks, or click blank then click option'

Aread

BreadWrite

CdbAdmin

DuserAdmin

Attempts:

3 left

💡 Hint

Common Mistakes

Omitting one of the roles reduces permissions.

This user has all three main built-in roles: read, readWrite, and dbAdmin for full access and management.

Practice

1. Which built-in MongoDB role allows a user to only view data without making any changes?

easy

A. root

B. readWrite

C. dbAdmin

D. read

Solution

1. Step 1: Understand the read role

   The read role allows users to view data but not modify it.

2. Step 2: Compare with other roles

   readWrite allows changes, dbAdmin manages settings, root has full access.

3. Final Answer:

   read -> Option D

4. Quick Check:

   View-only permission = read [OK]

Hint: View-only means read role [OK]

Common Mistakes:

• Confusing readWrite with read
• Thinking dbAdmin allows data viewing only
• Assuming root is for read-only

2. Which of the following is the correct way to assign the readWrite role to a user on the database mydb in MongoDB shell?

easy

A. db.grantRolesToUser('username', [{role: 'readWrite', db: 'mydb'}])

B. db.createUser({user: 'username', roles: ['readWrite']})

C. db.grantRolesToUser('username', ['readWrite'])

D. db.grantRolesToUser('username', [{role: 'readWrite', db: 'admin'}])

Solution

1. Step 1: Check syntax for granting roles

   The correct syntax uses db.grantRolesToUser with an array of role objects specifying role and database.

2. Step 2: Validate database name and role format

   db.grantRolesToUser('username', [{role: 'readWrite', db: 'mydb'}]) correctly specifies role as 'readWrite' and database as 'mydb'. db.grantRolesToUser('username', [{role: 'readWrite', db: 'admin'}]) wrongly uses 'admin' database.

3. Final Answer:

   db.grantRolesToUser('username', [{role: 'readWrite', db: 'mydb'}]) -> Option A

4. Quick Check:

   Grant role with role+db object array [OK]

Hint: Use role objects with db name in array for granting roles [OK]

Common Mistakes:

• Passing roles as simple strings without db
• Using wrong database name for the role
• Using createUser instead of grantRolesToUser for existing users

3. Given a user with the dbAdmin role on database sales, which of the following actions can the user perform?

medium

A. Create and drop indexes on collections

B. Insert new documents into collections

C. Read documents from collections

D. Modify documents in collections

Solution

1. Step 1: Understand dbAdmin role capabilities

   The dbAdmin role allows managing database settings like indexes, stats, and users, but not data changes.

2. Step 2: Match actions to role permissions

   Creating/dropping indexes is a dbAdmin task. Inserting, reading, or modifying documents require readWrite or read roles.

3. Final Answer:

   Create and drop indexes on collections -> Option A

4. Quick Check:

   dbAdmin manages indexes, not data changes [OK]

Hint: dbAdmin manages indexes, not data content [OK]

Common Mistakes:

• Assuming dbAdmin can insert or modify data
• Confusing readWrite with dbAdmin
• Thinking dbAdmin can read data

4. You tried to assign the readWrite role to a user with this command:
db.grantRolesToUser('alice', ['readWrite'])
But it failed. What is the likely cause?

medium

A. The user 'alice' does not exist

B. The role array must contain objects with role and db fields

C. The readWrite role does not exist

D. You must use createUser to assign roles

Solution

1. Step 1: Check syntax for grantRolesToUser

   The method requires an array of role objects with role and db fields, not just strings.

2. Step 2: Analyze the given command

   The command uses an array of strings, which is invalid syntax and causes failure.

3. Final Answer:

   The role array must contain objects with role and db fields -> Option B

4. Quick Check:

   Roles must be objects with role and db [OK]

Hint: Roles need role+db objects, not strings [OK]

Common Mistakes:

• Passing roles as strings instead of objects
• Assuming createUser is needed to add roles to existing users
• Ignoring user existence errors

5. You want a user to manage database indexes and view data but not modify documents. Which combination of built-in roles should you assign?

hard

A. readWrite only

B. dbAdmin only

C. read and dbAdmin

D. readWrite and dbAdmin

Solution

1. Step 1: Identify roles for viewing data and managing indexes

   read allows viewing data, dbAdmin allows managing indexes and database settings.

2. Step 2: Exclude roles that allow modifying documents

   readWrite allows modifying documents, which is not desired here.

3. Final Answer:

   read and dbAdmin -> Option C

4. Quick Check:

   View + manage indexes = read + dbAdmin [OK]

Hint: Combine read and dbAdmin to view and manage without edits [OK]

Common Mistakes:

• Using readWrite which allows document changes
• Assigning only dbAdmin which lacks read permission
• Assuming dbAdmin includes readWrite