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Building Scalable Applications with Thymeleaf and Spring Boot

Introduction to Displaying Data

Explore how to display data using Thymeleaf in a Spring Boot app by generating random users for testing, setting up the UserService interface, and configuring your database connection properties. This lesson helps you understand database initialization and service layer integration to prepare your application for data display.

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Generate random users

The first thing we need is a few users in our database for testing. We could create a database script to do that, but it’s easier to write a simple Java class that can create things in a loop.

Let’s start by creating a CommandLineRunner implementation. Spring will run any such beans at the startup of the application. By only enabling the bean when the init-db profile is active, we can toggle if the database should be populated at startup or not.

This is the code for the DatabaseInitializer:

Java
package com.tamingthymeleaf.application;
import com.github.javafaker.Faker;
import com.github.javafaker.Name;
import com.tamingthymeleaf.application.user.*;
import org.apache.commons.lang3.StringUtils;
import org.springframework.boot.CommandLineRunner;
import org.springframework.context.annotation.Profile;
import org.springframework.stereotype.Component;
import java.time.LocalDate;
import java.time.ZoneId;
@Component
@Profile("init-db") //<.>
public class DatabaseInitializer implements CommandLineRunner { //<.>
    private final Faker faker = new Faker(); //<.>
    private final UserService userService;
    public DatabaseInitializer(UserService userService) { //<.>
        this.userService = userService;
    }
    @Override
    public void run(String... args) {
        for (int i = 0; i < 20; i++) { //<.>
            CreateUserParameters parameters = newRandomUserParameters();
            userService.createUser(parameters);
        }
    }
    private CreateUserParameters newRandomUserParameters() {
        Name name = faker.name();
        UserName userName = new UserName(name.firstName(), name.lastName());
        Gender gender = faker.bool().bool() ? Gender.MALE : Gender.FEMALE;
        LocalDate birthday = LocalDate.ofInstant(faker.date().birthday(10, 40).toInstant(), ZoneId.systemDefault());
        Email email = new Email(faker.internet().emailAddress(generateEmailLocalPart(userName)));
        PhoneNumber phoneNumber = new PhoneNumber(faker.phoneNumber().phoneNumber());
        return new CreateUserParameters(userName, gender, birthday, email, phoneNumber);
    }
    private String generateEmailLocalPart(UserName userName) {
        return String.format("%s.%s",
                             StringUtils.remove(userName.getFirstName().toLowerCase(), "'"),
                             StringUtils.remove(userName.getLastName().toLowerCase(), "'"));
    }
}
  • Only have this @Component active when the init-db profile is active.
  • Implement CommandLineRunner interface so that
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