Custom role creation in MongoDB - Mini Project: Build & Apply

Create a Custom Role in MongoDB

📖 Scenario: You are a database administrator for a small company. You need to create a custom role in MongoDB that allows users to read data from the sales database and insert documents into the feedback collection within the customer database.

🎯 Goal: Build a MongoDB custom role named readSalesInsertFeedback with the exact privileges to read from the sales database and insert into the feedback collection of the customer database.

📋 What You'll Learn

Create a role named readSalesInsertFeedback

Grant find action on all collections in the sales database

Grant insert action on the feedback collection in the customer database

Use the db.createRole() method with the correct structure

💡 Why This Matters

🌍 Real World

Custom roles help control exactly what users can do in a MongoDB database, improving security and organization.

💼 Career

Database administrators and developers often create custom roles to tailor access permissions to business needs.

1

Setup Role Name and Empty Privileges

Create a variable called roleDefinition and assign it an object with the role set to "readSalesInsertFeedback" and an empty array for privileges. Also include roles as an empty array.

MongoDB

const roleDefinition = {
  role: "readSalesInsertFeedback",
  privileges: [],
  roles: []
};
// Your code here

Hint

Start by defining the role name and empty privileges and roles arrays.

2

Add Read Privilege on Sales Database

Add an object to roleDefinition.privileges granting the find action on the resource with db set to "sales" and collection set to an empty string (meaning all collections).

MongoDB

const roleDefinition = {
  role: "readSalesInsertFeedback",
  privileges: [
    // Add read privilege on sales database here
  ],
  roles: []
};
// Your code here

Hint

Use collection: "" to specify all collections in the sales database.

3

Add Insert Privilege on Feedback Collection

Add another object to roleDefinition.privileges granting the insert action on the resource with db set to "customer" and collection set to "feedback".

MongoDB

const roleDefinition = {
  role: "readSalesInsertFeedback",
  privileges: [
    {
      resource: { db: "sales", collection: "" },
      actions: ["find"]
    },
    // Add insert privilege on customer.feedback collection here
  ],
  roles: []
};
// Your code here

Hint

Specify the exact collection feedback in the customer database for the insert action.

4

Create the Role in MongoDB

Use db.createRole() with roleDefinition as the argument to create the custom role.

MongoDB

const roleDefinition = {
  role: "readSalesInsertFeedback",
  privileges: [
    {
      resource: { db: "sales", collection: "" },
      actions: ["find"]
    },
    {
      resource: { db: "customer", collection: "feedback" },
      actions: ["insert"]
    }
  ],
  roles: []
};

// Use db.createRole() to create the role
// Your code here

Hint

Call db.createRole() with the role definition object to create the role.

Practice

1. What is the main purpose of creating a custom role in MongoDB?

easy

A. To speed up database queries

B. To assign specific permissions tailored to user needs

C. To backup the database automatically

D. To create new collections in the database

Solution

1. Step 1: Understand role purpose

   Custom roles are designed to control what actions a user can perform.

2. Step 2: Match purpose to options

   Only To assign specific permissions tailored to user needs describes assigning specific permissions tailored to user needs.

3. Final Answer:

   To assign specific permissions tailored to user needs -> Option B

4. Quick Check:

   Custom role purpose = Assign specific permissions [OK]

Hint: Custom roles control user permissions precisely [OK]

Common Mistakes:

• Confusing roles with database backups
• Thinking roles speed up queries
• Assuming roles create collections

2. Which of the following is the correct syntax to create a custom role named readWriteReports with read and write privileges on the reports database?

easy

A. db.createRole({role: "readWriteReports", privileges: [{resource: {db: "reports"}, actions: ["readWrite"]}], roles: []})

B. db.createRole({role: "readWriteReports", privileges: [{resource: {db: "reports", collection: ""}, actions: ["find", "insert", "update"]}], roles: []})

C. db.createRole({name: "readWriteReports", privileges: [{resource: {db: "reports", collection: ""}, actions: ["find", "insert", "update"]}], roles: []})

D. db.createRole({name: "readWriteReports", privileges: [{resource: {db: "reports"}, actions: ["readWrite"]}], roles: []})

Solution

1. Step 1: Check correct field names

   The field for role name is name, not role.

2. Step 2: Verify privileges structure

   Privileges must specify resource with db and collection, and actions as an array of strings.

3. Final Answer:

   db.createRole({name: "readWriteReports", privileges: [{resource: {db: "reports", collection: ""}, actions: ["find", "insert", "update"]}], roles: []}) -> Option C

4. Quick Check:

   Use 'name' for role name and specify privileges correctly [OK]

Hint: Use 'name' key for role name in createRole [OK]

Common Mistakes:

• Using 'role' instead of 'name' for role name
• Omitting collection field in resource
• Using 'readWrite' as action instead of specific actions

3. Given the following command, what will be the effect of the custom role limitedUser?

db.createRole({
  name: "limitedUser",
  privileges: [
    { resource: { db: "sales", collection: "orders" }, actions: ["find"] }
  ],
  roles: []
})

medium

A. User has no permissions on sales.orders collection

B. User can read and write on sales.orders collection

C. User can perform any action on sales database

D. User can only read documents from sales.orders collection

Solution

1. Step 1: Analyze privileges actions

   The action specified is only "find", which means read access.

2. Step 2: Understand resource scope

   The resource is the "orders" collection in the "sales" database, so permissions apply only there.

3. Final Answer:

   User can only read documents from sales.orders collection -> Option D

4. Quick Check:

   Action 'find' = read only on specified collection [OK]

Hint: Action 'find' means read-only permission [OK]

Common Mistakes:

• Assuming 'find' allows write operations
• Thinking permissions apply to whole database
• Confusing empty roles array as full access

4. Identify the error in this custom role creation command:

db.createRole({
  name: "dataEditor",
  privileges: [
    { resource: { db: "analytics", collection: "reports" }, actions: "update" }
  ],
  roles: []
})

medium

A. The 'actions' field should be an array, not a string

B. The 'resource' field is missing the database name

C. The 'name' field should be 'role'

D. The 'roles' array cannot be empty

Solution

1. Step 1: Check 'actions' field type

   The 'actions' field must be an array of strings, but here it is a single string "update".

2. Step 2: Verify other fields

   The 'resource' includes both db and collection correctly; 'name' is correct; 'roles' can be empty.

3. Final Answer:

   The 'actions' field should be an array, not a string -> Option A

4. Quick Check:

   'actions' must be an array [OK]

Hint: Always use array for 'actions' even if one action [OK]

Common Mistakes:

• Using string instead of array for 'actions'
• Confusing 'name' with 'role' field
• Thinking 'roles' array cannot be empty

5. You want to create a custom role reportManager that allows users to read all collections in the reports database and also run the aggregate action on the summary collection only. Which of the following commands correctly implements this?

hard

A. db.createRole({name: "reportManager", privileges: [{resource: {db: "reports", collection: ""}, actions: ["find"]}, {resource: {db: "reports", collection: "summary"}, actions: ["aggregate"]}], roles: []})

B. db.createRole({name: "reportManager", privileges: [{resource: {db: "reports"}, actions: ["find"]}, {resource: {db: "reports", collection: "summary"}, actions: ["aggregate"]}], roles: []})

C. db.createRole({name: "reportManager", privileges: [{resource: {db: "reports", collection: "summary"}, actions: ["find", "aggregate"]}], roles: []})

D. db.createRole({name: "reportManager", privileges: [{resource: {db: "reports", collection: ""}, actions: ["find", "aggregate"]}], roles: []})

Solution

1. Step 1: Understand the requirements

   Users must have read (find) access on all collections in 'reports' and aggregate only on 'summary' collection.

2. Step 2: Check privileges for all collections

   Using collection: "" means all collections in the database, so first privilege grants find on all collections.

3. Step 3: Check aggregate privilege on summary

   Second privilege grants aggregate only on 'summary' collection.

4. Final Answer:

   db.createRole({name: "reportManager", privileges: [{resource: {db: "reports", collection: ""}, actions: ["find"]}, {resource: {db: "reports", collection: "summary"}, actions: ["aggregate"]}], roles: []}) -> Option A

5. Quick Check:

   Separate privileges for all collections and specific collection actions [OK]

Hint: Use empty string for all collections, specify collection for specific actions [OK]

Common Mistakes:

• Using db only without collection for find
• Combining find and aggregate on all collections
• Missing separate privilege for aggregate on summary