Data denormalization strategies in Firebase - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to create a denormalized data structure for a user's profile in Firebase.

Firebase

const userProfile = {
  name: "Alice",
  age: 30,
  posts: [1]
};

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

A["post1", "post2"]

B"post1"

C{post1: true, post2: true}

Dnull

Attempts:

3 left

💡 Hint

Common Mistakes

Using a single string instead of a list for multiple posts.

Using an object with true values which is less straightforward here.

Using an array of post IDs allows easy access to all posts related to the user, which is a common denormalization strategy.

2fill in blank

medium

Complete the code to update a user's post count in a denormalized Firebase database.

Firebase

firebase.database().ref('users/' + userId).update({
  postCount: [1]
});

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

Aposts

BpostsCount

Cposts.length

DpostCount + 1

Attempts:

3 left

💡 Hint

Common Mistakes

Using the length of posts array directly without updating.

Using an undefined variable like postsCount.

Incrementing the existing postCount by 1 keeps the denormalized count accurate after adding a new post.

3fill in blank

hard

Fix the error in the denormalized data update code to avoid overwriting unrelated data.

Firebase

firebase.database().ref('posts/' + postId).update({
  title: newTitle,
  content: newContent,
  [1]: newTimestamp
});

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

AupdatedAt

BcreatedAt

Ctimestamp

Dtime

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'createdAt' which does not change on updates.

Using generic names like 'time' which are unclear.

Using 'updatedAt' clearly indicates the time of the latest update, which is a best practice in denormalized data.

4fill in blank

hard

Fill both blanks to correctly denormalize user data and posts in Firebase.

Firebase

const denormalizedData = {
  users: {
    [1]: {
      name: userName,
      postCount: [2]
    }
  }
};

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

AuserId

BuserName

CpostCount

Dposts

Attempts:

3 left

💡 Hint

Common Mistakes

Using userName as a key instead of userId.

Using posts array instead of postCount for the count.

The userId is used as the key under 'users' to uniquely identify the user. The postCount stores the number of posts, which is a common denormalized field.

5fill in blank

hard

Fill all three blanks to correctly update denormalized post data with user info in Firebase.

Firebase

firebase.database().ref('posts/' + [1]).update({
  title: newTitle,
  authorName: [2],
  authorId: [3]
});

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

ApostId

BuserName

CuserId

DpostKey

Attempts:

3 left

💡 Hint

Common Mistakes

Using postKey instead of postId which may not be defined.

Mixing up userName and userId positions.

postId identifies the post to update. authorName and authorId store denormalized user info for quick access.