@ManyToOne relationship in Spring Boot - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to declare a many-to-one relationship in a Spring Boot entity.

Spring Boot

import jakarta.persistence.*;

@Entity
public class Order {
    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    private Long id;

    @[1]
    private Customer customer;

    // getters and setters
}

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AManyToMany

BManyToOne

COneToMany

DOneToOne

Attempts:

3 left

💡 Hint

Common Mistakes

Using @OneToMany instead of @ManyToOne

Forgetting to import the annotation

Confusing the direction of the relationship

The @ManyToOne annotation defines a many-to-one relationship from Order to Customer.

2fill in blank

medium

Complete the code to specify the foreign key column name for the many-to-one relationship.

Spring Boot

import jakarta.persistence.*;

@Entity
public class Order {
    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    private Long id;

    @ManyToOne
    @JoinColumn(name = "[1]")
    private Customer customer;

    // getters and setters
}

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Aorder_id

BcustomerName

Cid

Dcustomer_id

Attempts:

3 left

💡 Hint

Common Mistakes

Using the wrong column name that doesn't exist

Confusing the primary key column with the foreign key column

The @JoinColumn annotation specifies the foreign key column name in the Order table that references the Customer entity.

3fill in blank

hard

Fix the error in the code to correctly map the many-to-one relationship with lazy loading.

Spring Boot

import jakarta.persistence.*;

@Entity
public class Order {
    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    private Long id;

    @ManyToOne(fetch = FetchType.[1])
    @JoinColumn(name = "customer_id")
    private Customer customer;

    // getters and setters
}

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ALAZY

BIMMEDIATE

CDEFERRED

DEAGER

Attempts:

3 left

💡 Hint

Common Mistakes

Using EAGER when lazy loading is intended

Using invalid fetch type values

Using FetchType.LAZY delays loading the related Customer until it is accessed, improving performance.

4fill in blank

hard

Fill both blanks to complete the code for a bidirectional many-to-one relationship.

Spring Boot

import jakarta.persistence.*;
import java.util.List;

@Entity
public class Customer {
    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    private Long id;

    @[1](mappedBy = "customer")
    private List<Order> [2];

    // getters and setters
}

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AOneToMany

BManyToOne

Corders

DcustomerOrders

Attempts:

3 left

💡 Hint

Common Mistakes

Using @ManyToOne on the 'one' side

Using a singular field name for a list

The @OneToMany annotation on Customer defines the list of orders. The field name orders holds these related Order objects.

5fill in blank

hard

Fill all three blanks to complete the code for an Order entity with a many-to-one relationship and cascade persist.

Spring Boot

import jakarta.persistence.*;

@Entity
public class Order {
    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    private Long id;

    @ManyToOne(cascade = CascadeType.[1], fetch = FetchType.[2])
    @JoinColumn(name = "[3]")
    private Customer customer;

    // getters and setters
}

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APERSIST

BLAZY

Ccustomer_id

DREMOVE

Attempts:

3 left

💡 Hint

Common Mistakes

Using REMOVE cascade when not intended

Using EAGER fetch when lazy is better for performance

Wrong join column name

The cascade type PERSIST ensures saving the Customer when saving the Order. The fetch type LAZY delays loading the customer until needed. The join column customer_id is the foreign key.