Franscis123$# Comments - Answer Overflow

Franscis123$#

•Created by Franscis123$# on 3/30/2025 in #java-help

Searching DB registers by other field instead PK using JPA

 public User userByUsername(String username) {
    
    EntityManager em = getEntityManager();

    Query query = em.createQuery("SELECT u FROM User u WHERE u.username = :username");

    query.setParameter("username", username);

    User user;

    try { user = (User ) query.getSingleResult(); } catch (NoResultException e) {

        System.out.println("User not found");
        return null;

    }

    return user;

    }

 public User userByUsername(String username) {
    
    EntityManager em = getEntityManager();

    Query query = em.createQuery("SELECT u FROM User u WHERE u.username = :username");

    query.setParameter("username", username);

    User user;

    try { user = (User ) query.getSingleResult(); } catch (NoResultException e) {

        System.out.println("User not found");
        return null;

    }

    return user;

    }

I build my method like this, what you think?

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•Created by Franscis123$# on 3/30/2025 in #java-help

Searching DB registers by other field instead PK using JPA

Nothing, now I see that 'em' is initialized individually in each method and not globally.

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•Created by Franscis123$# on 3/30/2025 in #java-help

Searching DB registers by other field instead PK using JPA

If I need to use PersistenceContext, this will affect to others methods that uses 'em' ?

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•Created by Franscis123$# on 2/18/2025 in #java-help

Cannot invoke "jakarta.persistence.EntityManagerFactory.createEntityManager()" "this.emf" is null

No, Its just uses Maven, and me too

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•Created by Franscis123$# on 2/18/2025 in #java-help

Cannot invoke "jakarta.persistence.EntityManagerFactory.createEntityManager()" "this.emf" is null

Its calls to create method from RolJpaController create method. I'm new using JPA, and I watched a tutorials to apply it to my proyect, In its was done like that way.

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•Created by Franscis123$# on 2/18/2025 in #java-help

Cannot invoke "jakarta.persistence.EntityManagerFactory.createEntityManager()" "this.emf" is null

Rol

package org.logic;

import jakarta.persistence.*;
import java.io.Serializable;
import java.util.Date;
import java.util.Set;

@Entity
@Table(name = "rol")
public class Rol implements Serializable {

    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    @Column(name = "id")
    private Long id;

    @Column(length = 30, unique = true, name = "rol")
    private String rol;

    @Temporal(TemporalType.TIMESTAMP)
    @Column(name = "created_at")
    private Date created_at;

    @Temporal(TemporalType.TIMESTAMP)
    @Column(name = "updated_at")
    private Date updated_at;

    @ManyToMany(mappedBy = "roles")
    private Set<Action> actions;

    public Rol() {}

    public Rol(String rol, Date created_at) {

        this.rol = rol;
        this.created_at = created_at;

    }

    public Long getId() { return id; }

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

    public String getRol() { return rol; }

    public void setRole(String rol) { this.rol = rol; }

    public Date getCreated_at() { return created_at; }

    public void setCreated_at(Date created_at) { this.created_at = created_at; }

    public Date getUpdated_at() { return updated_at; }

    public void setUpdated_at(Date updated_at) { this.updated_at = updated_at; }

    public Set<Action> getActions() { return actions; }

    public void setActions(Set<Action> actions) { this.actions = actions; }

  }

package org.logic;

import jakarta.persistence.*;
import java.io.Serializable;
import java.util.Date;
import java.util.Set;

@Entity
@Table(name = "rol")
public class Rol implements Serializable {

    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    @Column(name = "id")
    private Long id;

    @Column(length = 30, unique = true, name = "rol")
    private String rol;

    @Temporal(TemporalType.TIMESTAMP)
    @Column(name = "created_at")
    private Date created_at;

    @Temporal(TemporalType.TIMESTAMP)
    @Column(name = "updated_at")
    private Date updated_at;

    @ManyToMany(mappedBy = "roles")
    private Set<Action> actions;

    public Rol() {}

    public Rol(String rol, Date created_at) {

        this.rol = rol;
        this.created_at = created_at;

    }

    public Long getId() { return id; }

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

    public String getRol() { return rol; }

    public void setRole(String rol) { this.rol = rol; }

    public Date getCreated_at() { return created_at; }

    public void setCreated_at(Date created_at) { this.created_at = created_at; }

    public Date getUpdated_at() { return updated_at; }

    public void setUpdated_at(Date updated_at) { this.updated_at = updated_at; }

    public Set<Action> getActions() { return actions; }

    public void setActions(Set<Action> actions) { this.actions = actions; }

  }

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•Created by Franscis123$# on 2/18/2025 in #java-help

Cannot invoke "jakarta.persistence.EntityManagerFactory.createEntityManager()" "this.emf" is null

Main

package org.logic;

import java.util.Date;

public class Main {

  public static void main (String[] args){

 LogicController LogicCtl = new LogicController();

        Rol role = new Rol("admin", new Date());

        LogicCtl.createRol(role);

}

}

package org.logic;

import java.util.Date;

public class Main {

  public static void main (String[] args){

 LogicController LogicCtl = new LogicController();

        Rol role = new Rol("admin", new Date());

        LogicCtl.createRol(role);

}

}

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•Created by Franscis123$# on 2/18/2025 in #java-help

Cannot invoke "jakarta.persistence.EntityManagerFactory.createEntityManager()" "this.emf" is null

LogicController

package org.logic;

import org.persistence.PersistenceController;

public class LogicController {

    PersistenceController PersistenceCtl = new PersistenceController();

    public void createAction (Action act){ PersistenceCtl.createAction(act); }

    public void createRol(Rol rol){ PersistenceCtl.createRol(rol); }

}

package org.logic;

import org.persistence.PersistenceController;

public class LogicController {

    PersistenceController PersistenceCtl = new PersistenceController();

    public void createAction (Action act){ PersistenceCtl.createAction(act); }

    public void createRol(Rol rol){ PersistenceCtl.createRol(rol); }

}

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•Created by Franscis123$# on 2/3/2025 in #java-help

The collection of metamodel types is empty

How could create the EntityManagerFactory in the Persistence Controller?

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•Created by Franscis123$# on 2/3/2025 in #java-help

The collection of metamodel types is empty

Also I used NetBeans only to generate the JpaControllers, because IntelliJ Community don't have these options with premium, and it generate one for each class.

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•Created by Franscis123$# on 2/3/2025 in #java-help

The collection of metamodel types is empty

I don't tried it because I don't have tables in my database

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•Created by Franscis123$# on 2/3/2025 in #java-help

The collection of metamodel types is empty

IntelliJ IDEA Community

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•Created by Franscis123$# on 2/3/2025 in #java-help

The collection of metamodel types is empty

I created a JpaController class for each class

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•Created by Franscis123$# on 2/3/2025 in #java-help

The collection of metamodel types is empty

package org.logic;

import org.persistence.PersistenceController;

public class Main {

    public static void main(String[] args) {

        PersistenceController PerCtrl = new PersistenceController();

    }

}

package org.logic;

import org.persistence.PersistenceController;

public class Main {

    public static void main(String[] args) {

        PersistenceController PerCtrl = new PersistenceController();

    }

}

package org.persistence;

public class PersistenceController {

    ActionJpaController ActJpaCtrl = new ActionJpaController();
    FlavorJpaController FlvJpaCtrl = new FlavorJpaController();
    Ice_CreamJpaController IceJpaCtrl = new Ice_CreamJpaController();
    InvoiceJpaController InvJpaCtrl = new InvoiceJpaController();
    OrdenJpaController OrdJpaCtrl = new OrdenJpaController();
    RoleJpaController RolJpaCtrl = new RoleJpaController();
    SizeJpaController SizJpaCtrl = new SizeJpaController();
    UserJpaController UsrJpaCtrl = new UserJpaController();


}

package org.persistence;

public class PersistenceController {

    ActionJpaController ActJpaCtrl = new ActionJpaController();
    FlavorJpaController FlvJpaCtrl = new FlavorJpaController();
    Ice_CreamJpaController IceJpaCtrl = new Ice_CreamJpaController();
    InvoiceJpaController InvJpaCtrl = new InvoiceJpaController();
    OrdenJpaController OrdJpaCtrl = new OrdenJpaController();
    RoleJpaController RolJpaCtrl = new RoleJpaController();
    SizeJpaController SizJpaCtrl = new SizeJpaController();
    UserJpaController UsrJpaCtrl = new UserJpaController();


}

package org.persistence;

import jakarta.persistence.*;
import java.io.Serializable;
import jakarta.persistence.criteria.CriteriaQuery;
import jakarta.persistence.criteria.Root;
import org.logic.Role;
import java.util.ArrayList;
import java.util.List;
import org.logic.Action;
import org.persistence.exceptions.NonexistentEntityException;

public class ActionJpaController implements Serializable {

    public ActionJpaController(EntityManagerFactory emf) {
        this.emf = emf;
    }

    public ActionJpaController() { emf = Persistence.createEntityManagerFactory("IceCreamShopPU"); }

    private EntityManagerFactory emf = null;

    public EntityManager getEntityManager() {
        return emf.createEntityManager();
    }

package org.persistence;

import jakarta.persistence.*;
import java.io.Serializable;
import jakarta.persistence.criteria.CriteriaQuery;
import jakarta.persistence.criteria.Root;
import org.logic.Role;
import java.util.ArrayList;
import java.util.List;
import org.logic.Action;
import org.persistence.exceptions.NonexistentEntityException;

public class ActionJpaController implements Serializable {

    public ActionJpaController(EntityManagerFactory emf) {
        this.emf = emf;
    }

    public ActionJpaController() { emf = Persistence.createEntityManagerFactory("IceCreamShopPU"); }

    private EntityManagerFactory emf = null;

    public EntityManager getEntityManager() {
        return emf.createEntityManager();
    }

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•Created by Franscis123$# on 2/3/2025 in #java-help

The collection of metamodel types is empty

Adding

<exclude-unlisted-classes>false</exclude-unlisted-classes>

<exclude-unlisted-classes>false</exclude-unlisted-classes>

to persistence.xml don't solve it, neither with true

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•Created by Franscis123$# on 2/3/2025 in #java-help

The collection of metamodel types is empty

      <dependency>
            <groupId>org.eclipse.persistence</groupId>
            <artifactId>org.eclipse.persistence.antlr</artifactId>
            <version>2.7.12</version>
        </dependency>
        <dependency>
            <groupId>org.eclipse.persistence</groupId>
            <artifactId>org.eclipse.persistence.jpa</artifactId>
            <version>4.0.5</version>
        </dependency>
        <dependency>
            <groupId>org.eclipse.persistence</groupId>
            <artifactId>org.eclipse.persistence.jpa.jpql</artifactId>
            <version>4.0.5</version>
        </dependency>
        <dependency>
            <groupId>org.eclipse.persistence</groupId>
            <artifactId>org.eclipse.persistence.moxy</artifactId>
            <version>4.0.4</version>
        </dependency>
        <dependency>
            <groupId>org.eclipse.persistence</groupId>
            <artifactId>jakarta.persistence</artifactId>
            <version>2.2.3</version>
        </dependency>
        <dependency>
            <groupId>org.eclipse.persistence</groupId>
            <artifactId>org.eclipse.persistence.jpa.modelgen.processor</artifactId>
            <version>4.0.4-RC1</version>
            <scope>provided</scope>
        </dependency>
        <dependency>
            <groupId>jakarta.persistence</groupId>
            <artifactId>jakarta.persistence-api</artifactId>
            <version>3.2.0</version>
        </dependency>
        <dependency>
            <groupId>org.slf4j</groupId>
            <artifactId>slf4j-simple</artifactId>
            <version>2.0.13</version>
        </dependency>
    </dependencies>
    <properties>
        <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
        <maven.compiler.source>17</maven.compiler.source>
        <maven.compiler.target>17</maven.compiler.target>
        <exec.mainClass>org.icecreamshop.IceCreamShop</exec.mainClass>
    </properties>
</project>

      <dependency>
            <groupId>org.eclipse.persistence</groupId>
            <artifactId>org.eclipse.persistence.antlr</artifactId>
            <version>2.7.12</version>
        </dependency>
        <dependency>
            <groupId>org.eclipse.persistence</groupId>
            <artifactId>org.eclipse.persistence.jpa</artifactId>
            <version>4.0.5</version>
        </dependency>
        <dependency>
            <groupId>org.eclipse.persistence</groupId>
            <artifactId>org.eclipse.persistence.jpa.jpql</artifactId>
            <version>4.0.5</version>
        </dependency>
        <dependency>
            <groupId>org.eclipse.persistence</groupId>
            <artifactId>org.eclipse.persistence.moxy</artifactId>
            <version>4.0.4</version>
        </dependency>
        <dependency>
            <groupId>org.eclipse.persistence</groupId>
            <artifactId>jakarta.persistence</artifactId>
            <version>2.2.3</version>
        </dependency>
        <dependency>
            <groupId>org.eclipse.persistence</groupId>
            <artifactId>org.eclipse.persistence.jpa.modelgen.processor</artifactId>
            <version>4.0.4-RC1</version>
            <scope>provided</scope>
        </dependency>
        <dependency>
            <groupId>jakarta.persistence</groupId>
            <artifactId>jakarta.persistence-api</artifactId>
            <version>3.2.0</version>
        </dependency>
        <dependency>
            <groupId>org.slf4j</groupId>
            <artifactId>slf4j-simple</artifactId>
            <version>2.0.13</version>
        </dependency>
    </dependencies>
    <properties>
        <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
        <maven.compiler.source>17</maven.compiler.source>
        <maven.compiler.target>17</maven.compiler.target>
        <exec.mainClass>org.icecreamshop.IceCreamShop</exec.mainClass>
    </properties>
</project>

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•Created by Franscis123$# on 2/3/2025 in #java-help

The collection of metamodel types is empty

pom.xml:

<?xml version="1.0" encoding="UTF-8"?>
<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
    <modelVersion>4.0.0</modelVersion>
    <groupId>org</groupId>
    <artifactId>IceCreamShop</artifactId>
    <version>1.0-SNAPSHOT</version>
    <packaging>jar</packaging>
    <dependencies>
        <dependency>
            <groupId>org.mariadb.jdbc</groupId>
            <artifactId>mariadb-java-client</artifactId>
            <version>3.4.1</version>
        </dependency>
        <dependency>
            <groupId>org.eclipse.persistence</groupId>
            <artifactId>org.eclipse.persistence.core</artifactId>
            <version>4.0.5</version>
        </dependency>
        <dependency>
            <groupId>org.eclipse.persistence</groupId>
            <artifactId>org.eclipse.persistence.asm</artifactId>
<version>9.4.0</version>
        </dependency>

<?xml version="1.0" encoding="UTF-8"?>
<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
    <modelVersion>4.0.0</modelVersion>
    <groupId>org</groupId>
    <artifactId>IceCreamShop</artifactId>
    <version>1.0-SNAPSHOT</version>
    <packaging>jar</packaging>
    <dependencies>
        <dependency>
            <groupId>org.mariadb.jdbc</groupId>
            <artifactId>mariadb-java-client</artifactId>
            <version>3.4.1</version>
        </dependency>
        <dependency>
            <groupId>org.eclipse.persistence</groupId>
            <artifactId>org.eclipse.persistence.core</artifactId>
            <version>4.0.5</version>
        </dependency>
        <dependency>
            <groupId>org.eclipse.persistence</groupId>
            <artifactId>org.eclipse.persistence.asm</artifactId>
<version>9.4.0</version>
        </dependency>

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•Created by Franscis123$# on 2/3/2025 in #java-help

The collection of metamodel types is empty

All of my classes have a similar mapping:

package org.logic;

import java.io.Serializable;
import javax.persistence.*;
import java.util.List;

@Entity
public class Action implements Serializable {

    @Id
    @GeneratedValue(strategy = GenerationType.SEQUENCE)
    private int act_id;


    @Column(unique=true)
    private String action;

    @ManyToMany
    private List<Role> roles;

//Contructors, getters and setters, etc.

package org.logic;

import java.io.Serializable;
import javax.persistence.*;
import java.util.List;

@Entity
public class Action implements Serializable {

    @Id
    @GeneratedValue(strategy = GenerationType.SEQUENCE)
    private int act_id;


    @Column(unique=true)
    private String action;

    @ManyToMany
    private List<Role> roles;

//Contructors, getters and setters, etc.

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•Created by Franscis123$# on 1/30/2025 in #java-help

No Persistence provider for EntityManager named IceCreamShopPU

I put it before <persistence-unit> and marks it as wrong

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•Created by Franscis123$# on 1/30/2025 in #java-help

No Persistence provider for EntityManager named IceCreamShopPU

This is incomplete or is just that?

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