Associations (hasMany, belongsTo) in Express - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to define a one-to-many association where a User has many Posts.

Express

User.[1](Post);

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

AbelongsToMany

BbelongsTo

ChasOne

DhasMany

Attempts:

3 left

💡 Hint

Common Mistakes

Using belongsTo instead of hasMany reverses the relationship.

Using hasOne limits to only one related record.

In Express with Sequelize, hasMany sets a one-to-many relationship from User to Post.

2fill in blank

medium

Complete the code to define the inverse association where a Post belongs to a User.

Express

Post.[1](User);

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

AbelongsTo

BhasOne

ChasMany

DbelongsToMany

Attempts:

3 left

💡 Hint

Common Mistakes

Using hasMany here would incorrectly imply a Post owns many Users.

Using hasOne is not correct for the inverse of hasMany.

The belongsTo method sets the inverse of a hasMany association, linking Post back to User.

3fill in blank

hard

Fix the error in the association code to correctly link Comment to Post.

Express

Comment.[1](Post);

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

AhasMany

BbelongsTo

ChasOne

DbelongsToMany

Attempts:

3 left

💡 Hint

Common Mistakes

Using hasMany here would imply Comment owns many Posts, which is incorrect.

Using hasOne would limit Comment to only one Post but is less clear than belongsTo.

Each Comment belongs to one Post, so belongsTo is the correct association method.

4fill in blank

hard

Fill both blanks to create a bidirectional association between Author and Book.

Express

Author.[1](Book);
Book.[2](Author);

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

AhasMany

BbelongsTo

ChasOne

DbelongsToMany

Attempts:

3 left

💡 Hint

Common Mistakes

Swapping hasMany and belongsTo reverses the relationship.

Using belongsToMany is for many-to-many, not one-to-many.

Authors can have many Books (hasMany), and each Book belongs to one Author (belongsTo).

5fill in blank

hard

Fill all four blanks to define a many-to-many association between Student and Course using Enrollment.

Express

Student.[1](Course, { through: Enrollment });
Course.[2](Student, { through: Enrollment });
Enrollment.[3](Student);
Enrollment.[4](Course);

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

AhasMany

BbelongsTo

CbelongsToMany

DhasOne

Attempts:

3 left

💡 Hint

Common Mistakes

Using hasMany or hasOne instead of belongsToMany for many-to-many.

Not linking the join table back to the models with belongsTo.

Many-to-many associations use belongsToMany on both models with a join table. The join table belongsTo each model.