fixed many to many mapping by using an Association Table, related to …

…this SO question #https://stackoverflow.com/questions/77943523 . Not related to the SO question I also have bat colors and car colors show up as a CSV on the table, but so far have failed to populate the combo box with those values.

src/main/java/com/example/application/data/Car.java

@@ -1,6 +1,7 @@
 package com.example.application.data;
 
 import com.fasterxml.jackson.annotation.JsonBackReference;
+import com.fasterxml.jackson.annotation.JsonManagedReference;
 import jakarta.persistence.*;
 import jakarta.validation.constraints.Email;
 import org.hibernate.annotations.LazyCollection;
@@ -15,9 +16,9 @@ public class Car extends AbstractEntity {
 
 	private String color;
 
-    @JsonBackReference
-    @ManyToMany(mappedBy="cars")
-    private Set<SamplePerson> drivers;
+    @JsonManagedReference
+    @OneToMany(cascade = CascadeType.ALL, fetch = FetchType.EAGER, mappedBy = "car")
+    private Set<SamplePersonAssocCar> drivers;
 
     public String getColor() {
         return color;
@@ -26,8 +27,8 @@ public void setColor(String value) {
         this.color = value;
     }
 
-    public Set<SamplePerson> getDrivers() { return drivers;}
-    public void setDrivers(Set<SamplePerson> value){
+    public Set<SamplePersonAssocCar> getDrivers() { return drivers;}
+    public void setDrivers(Set<SamplePersonAssocCar> value){
         this.drivers = value;
     }
 

src/main/java/com/example/application/data/SamplePerson.java

@@ -19,15 +19,11 @@ public class SamplePerson extends AbstractEntity {
     @OneToMany(cascade = CascadeType.ALL, fetch = FetchType.EAGER, mappedBy = "zooKeeper")
     private Set<Bat> bats;
 
-    private String favoriteBatColor;
+    private String favoriteBatColor = "soup";
+
     @JsonManagedReference
-    @ManyToMany
-    @JoinTable(
-            name = "CAR_DRIVER_ASSOC",
-            joinColumns = {@JoinColumn(name="CAR_ID")},
-            inverseJoinColumns = {@JoinColumn(name="ID")}
-    )
-    private Set<Car> cars;
+    @OneToMany(cascade = CascadeType.ALL, fetch = FetchType.EAGER, mappedBy = "samplePerson")
+    private Set<SamplePersonAssocCar> cars;
     private String d;
     private String e;
 
@@ -45,16 +41,37 @@ public Set<Bat> getBats() {
     public void setBats(Set<Bat> value) {
         this.bats = value;
     }
+
+    public List<String> getAllBatColors(){
+        List<String> re = new ArrayList<String>();
+        bats.forEach((bat) -> {
+            re.add(bat.getColor());
+        });
+        return re;
+    }
+    public String getAllBatColorsCsv(){
+        return getAllBatColors().toString();
+    }
+    public List<String> getAllCarColors(){
+        List<String> re = new ArrayList<String>();
+        cars.forEach((car) -> {
+            re.add(car.getCar().getColor());
+        });
+        return re;
+    }
+    public String getAllCarColorsCsv(){
+        return getAllCarColors().toString();
+    }
     public String getFavoriteBatColor(){
         return favoriteBatColor;
     }
     public void setFavoriteBatColor(String value){
         this.favoriteBatColor = value;
     }
-    public Set<Car> getCars() {
+    public Set<SamplePersonAssocCar> getCars() {
         return cars;
     }
-    public void setCars(Set<Car> value) {
+    public void setCars(Set<SamplePersonAssocCar> value) {
         this.cars = value;
     }
     public String getD() {

src/main/java/com/example/application/data/SamplePersonAssocCar.java

@@ -0,0 +1,42 @@
+package com.example.application.data;
+
+import com.fasterxml.jackson.annotation.JsonBackReference;
+import com.fasterxml.jackson.annotation.JsonManagedReference;
+import jakarta.persistence.*;
+import jakarta.validation.constraints.Email;
+import org.hibernate.annotations.LazyCollection;
+import org.hibernate.annotations.LazyCollectionOption;
+
+import java.time.LocalDate;
+import java.time.LocalDateTime;
+import java.util.Set;
+
+@Entity
+public class SamplePersonAssocCar extends AbstractEntity {
+
+    @JsonBackReference
+    @ManyToOne
+    @JoinColumn(name = "samplePerson")
+    private SamplePerson samplePerson;
+
+    @JsonBackReference
+    @ManyToOne
+    @JoinColumn(name = "car")
+    private Car car;
+
+    public SamplePerson getSamplePerson() {
+        return samplePerson;
+    }
+    public void setSamplePerson(SamplePerson value) {
+        this.samplePerson = value;
+    }
+
+    public Car getCar() {
+        return car;
+    }
+    public void setCar(Car value) {
+        this.car = value;
+    }
+
+
+}

src/main/java/com/example/application/data/SamplePersonAssocCarRepository.java

@@ -0,0 +1,12 @@
+package com.example.application.data;
+
+
+import org.springframework.data.jpa.repository.JpaRepository;
+import org.springframework.data.jpa.repository.JpaSpecificationExecutor;
+
+public interface SamplePersonAssocCarRepository
+        extends
+            JpaRepository<SamplePersonAssocCar, Long>,
+            JpaSpecificationExecutor<SamplePersonAssocCar> {
+
+}

src/main/java/com/example/application/views/masterdetail/MasterDetailView.java

@@ -29,6 +29,8 @@
 import com.vaadin.flow.router.PageTitle;
 import com.vaadin.flow.router.Route;
 import com.vaadin.flow.spring.data.VaadinSpringDataHelpers;
+
+import java.util.List;
 import java.util.Optional;
 import org.springframework.data.domain.PageRequest;
 import org.springframework.orm.ObjectOptimisticLockingFailureException;
@@ -45,6 +47,10 @@ public class MasterDetailView extends Div implements BeforeEnterObserver {
 
     private TextField ape_color;
     private ComboBox<String> batColors;
+
+    //private List<String> allBatColors;
+    private TextField allBatColorsCsv;
+    private TextField allCarColorsCsv;
     //private TextField c;
     private TextField d;
     private TextField e;
@@ -74,6 +80,9 @@ public MasterDetailView(SamplePersonService samplePersonService) {
         grid.addColumn("ape.color").setHeader("Ape Color").setAutoWidth(true);
         grid.addColumn("favoriteBatColor").setAutoWidth(true);
         //grid.addColumn("c").setAutoWidth(true);
+        //grid.addColumn("allBatColorsCsv").setAutoWidth(true);
+        grid.addColumn("allBatColorsCsv").setAutoWidth(true);
+        grid.addColumn("allCarColorsCsv").setAutoWidth(true);
         grid.addColumn("d").setAutoWidth(true);
         grid.addColumn("e").setAutoWidth(true);
 
@@ -100,6 +109,7 @@ public MasterDetailView(SamplePersonService samplePersonService) {
                 samplePerson -> samplePerson.getApe().getColor(),
                 (samplePerson, value) -> samplePerson.getApe().setColor(value));
 
+
         // Bind fields. This is where you'd define e.g. validation rules
 
         binder.bindInstanceFields(this);
@@ -160,13 +170,21 @@ private void createEditorLayout(SplitLayout splitLayout) {
 
         FormLayout formLayout = new FormLayout();
         ape_color = new TextField("Ape Color");
+        //allBatColorsCsv = new TextField("allBatColorsCsv");
         batColors = new ComboBox<>("Bat Colors");
+        //2//allBatColors = new ComboBox<>("All Bat Colors");
         //c = new TextField("c");
         d = new TextField("d");
         e = new TextField("e");
-        batColors.setItems("black","brown","white","blue","red");
 
-        formLayout.add(ape_color, batColors, /*c,*/ d, e);
+
+        if(samplePerson!=null) {
+            String allBatColorsCsv = samplePerson.getAllBatColorsCsv();
+            String[] allBatColors = allBatColorsCsv.split(",");
+            batColors.setItems(allBatColors);
+        }
+
+        formLayout.add(ape_color, batColors, d, e);
 
         editorDiv.add(formLayout);
         createButtonLayout(editorLayoutDiv);

src/main/resources/data.sql

@@ -1,7 +1,13 @@
 insert into ape(version, id, color) values (1, 1, 'apricot')
+insert into ape(version, id, color) values (1, 2, 'apple')
 insert into car(version, id, color) values (1, 1, 'cocoa')
 insert into car(version, id, color) values (1, 2, 'cream')
-insert into sample_person(version, id, ape, cars, d, e) values (1, 1, 1, ARRAY [1, 2], 'd', 'e')
-insert into bat(version, id, color, zooKeeper) values (1, 1, 'brown', 1)
-insert into bat(version, id, color, zooKeeper) values (1, 2, 'blue', 1)
+insert into sample_person(version, id, ape, d, e) values (1, 1, 1, 'd', 'e')
+insert into sample_person(version, id, ape, d, e) values (1, 2, 2, 'd', 'e')
+insert into sample_person_assoc_car(version, id, sample_person, car) values (1,1,1,1)
+insert into sample_person_assoc_car(version, id, sample_person, car) values (1,2,1,2)
+insert into sample_person_assoc_car(version, id, sample_person, car) values (1,3,2,2)
+insert into bat(version, id, color, zookeeper) values (1, 1, 'brown', 1)
+insert into bat(version, id, color, zookeeper) values (1, 2, 'blue', 1)
+insert into bat(version, id, color, zookeeper) values (1, 2, 'burgundy', 2)