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Spring Data: Bridging Multiple Databases

Solution: Reservation Queue

Explore how to implement a book reservation queue using Spring Data Redis by creating domain models like Book, User, and ReservationQueue. Understand setting up Redis hashes with annotations, defining repository interfaces for CRUD operations, and implementing the loanBook method to handle book loans and reservation queues efficiently.

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Solution

Let’s discuss the solution for implementing a book reservation queue.

Update the Book class

First, we add the Boolean available property to the Book class.

Java
package com.smartdiscover.model;
import lombok.Data;
import org.springframework.data.redis.core.RedisHash;
import org.springframework.data.redis.core.index.Indexed;
import java.io.Serializable;
import java.util.List;
import java.util.stream.Collectors;
@RedisHash("Book")
@Data
public class Book implements Serializable {
    private String id;
    @Indexed
    private String name;
    private String summary;
    private Boolean available;
    private List<Author> authors;
    @Override
    public String toString() {
        return "Book{" +
                "id=" + id +
                ", name='" + name + '\'' +
                ", summary='" + summary + '\'' +
                ((null != authors) ? ", authors=" + authors.stream().map(i -> i.getFullName()).collect(Collectors.toList()) + '\'' : "") +
                '}';
    }
}

Create the User class

Then, we create the User class in the com.smartdiscover.model package.

Java
package com.smartdiscover.model;
import lombok.Data;
import org.springframework.data.redis.core.RedisHash;
import org.springframework.data.redis.core.index.Indexed;
@RedisHash("User")
@Data
public class User {
    private String id;
    @Indexed
    private String firstName;
    @Indexed
    private String lastName;
}

Here’s an explanation of the code:

  • Lines 7–9: We add annotations like @Data and @RedisHash to transform a class into a Redis hash.

  • Line 11: We add the id identifier.

  • Lines 13 and 14: We add the firstName property with the @Indexed annotation to let Redis index the property values.

  • Lines 16 and 17: We add the lastName property with the @Indexed annotation. ...