Darko Luketic, Author at blog.icod.de

Spring Data JPA fixtures

14. March 2022

What are fixtures? Fixed data that is always present in the database. You can think of it as the initial dataset. application.properties

spring.jpa.hibernate.ddl-auto=create
spring.jpa.generate-ddl=true
spring.jpa.open-in-view=false
spring.sql.init.mode=always
spring.sql.init.data-locations=classpath:db/data.sql
spring.jpa.defer-datasource-initialization=true

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spring.jpa.hibernate.ddl-auto=create

spring.jpa.generate-ddl=true

spring.jpa.open-in-view=false

spring.sql.init.mode=always

spring.sql.init.data-locations=classpath:db/data.sql

spring.jpa.defer-datasource-initialization=true

The documentation speaks of “the root classpath”, not knowing Java well I had no idea what that means and an answer on Stackoverflow was of course wrong. It’s not the “src” dir, […]

Spring Data JPA Postgres UUID @Id

14. March 2022

I read lots of outdated info on this matter. Using PostgreSQL v13+ there is a function called gen_random_uuid(). See the manual page of Postgres UUID. Here’s an example entity called Page

package de.icod.blog.model;

import javax.persistence.*;
import java.util.UUID;

@Entity
@Table(name = "page")
public class Page {
    @Id
    @GeneratedValue(strategy = GenerationType.AUTO)
    @Column(name = "id", nullable = false, columnDefinition = "UUID default gen_random_uuid()")
    private UUID id;

    public UUID getId() {
        return id;
    }

    public void setId(UUID id) {
        this.id = id;
    }
}

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package de.icod.blog.model;

import javax.persistence.*;

import java.util.UUID;

@Entity

@Table(name = "page")

public class Page {

@Id

@GeneratedValue(strategy = GenerationType.AUTO)

@Column(name = "id", nullable = false, columnDefinition = "UUID default gen_random_uuid()")

private UUID id;

public UUID getId() {

return id;

}

public void setId(UUID id) {

this.id = id;

}

As you see you can append the columnDefinition to the @Column annotation. “UUID default gen_random_uuid()” This translates to following SQL

create table page
(
    id uuid default gen_random_uuid() not null
        constraint "primary"
            primary key
);

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create table page

(

id uuid default gen_random_uuid() not null

constraint "primary"

primary key

);

And you […]

Easily remember ManyToMany ManyToOne OneToMany

14. March 2022

ManyToMany in a Person Blog Relationship A Person can be a subscriber of many blogs. A Blog can have many subscribers.

const Person = {
  isSubscriberOfBlogs: []
}
const Blog = {
  subscribers = []
}

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const Person = {

isSubscriberOfBlogs: []

}

const Blog = {

subscribers = []

}

But since this is an inefficient way to manage usually a proxy table is used with [PersonID], [BlogID], aka the 2 related data models. ManyToOne and OneToMany in a Person Blog Relationship A […]

Vue composition api: ensure variable is not null

11. March 2022

I ran into a problem where I was loading data from the backend in App.vue and when loaded that data would be inserted into a vuex store and in another component queried. However the loading took longer than expected and a data race happened. The route destination rendered faster than the backend could deliver data […]

o2 DNS Auflösung mit Fehlern oder langsam

4. March 2022

Es ist der 04.03.2022 seit ca. 18 Uhr funktioniert die DNS Auflösung bei O2 garnicht oder nur sehr langsam. Vor allem Google scheint probleme zu haben, aber nicht nur Google. Es ist bei mir Rechner- und Domänenübergreifend. O2 in Göppingen, welches ca. 40km östlich von Stuttgart liegt. Ich hab sie vorübergehend überbrückt mit meinem Server, […]