Merge pull request #81 from fujaba/fix/unidirectional-link

Proper support for unidirectional associations

doc/ClassModelDefinition.md

@@ -184,13 +184,19 @@ class University
 {
    @Link("uni")
    List<Student> students;
+
+   @Link
+   Person president;
+
+   @Link
+   List<Person> employees;
 }
 ```
 <!-- end_code_fragment: -->
 
-The `@Link` annotation is intended for *bidirectional* associations.
+The `@Link` annotation is primarily intended for *bidirectional* associations.
 The generated code will ensure referential integrity when setting a student's university or when adding or removing students to a university.
-*Unidirectional* associations behave no different from attributes, so there is no special annotation for them.
+In case you want a *unidirectional* association, you can simply omit the annotation argument, as shown with `president` and `employees` in the `University` example.
 
 <!-- insert_code_fragment: docs.Student | fenced:java -->
 ```java
@@ -238,7 +244,11 @@ public class Student
 public class University
 {
    public static final String PROPERTY_STUDENTS = "students";
+   public static final String PROPERTY_PRESIDENT = "president";
+   public static final String PROPERTY_EMPLOYEES = "employees";
    private List<Student> students;
+   private Person president;
+   private List<Person> employees;
 
    public List<Student> getStudents()
    {
@@ -304,9 +314,85 @@ public class University
       return this;
    }
 
+   public Person getPresident()
+   {
+      return this.president;
+   }
+
+   public University setPresident(Person value)
+   {
+      this.president = value;
+      return this;
+   }
+
+   public List<Person> getEmployees()
+   {
+      return this.employees != null ? Collections.unmodifiableList(this.employees) : Collections.emptyList();
+   }
+
+   public University withEmployees(Person value)
+   {
+      if (this.employees == null)
+      {
+         this.employees = new ArrayList<>();
+      }
+      if (!this.employees.contains(value))
+      {
+         this.employees.add(value);
+      }
+      return this;
+   }
+
+   public University withEmployees(Person... value)
+   {
+      for (final Person item : value)
+      {
+         this.withEmployees(item);
+      }
+      return this;
+   }
+
+   public University withEmployees(Collection<? extends Person> value)
+   {
+      for (final Person item : value)
+      {
+         this.withEmployees(item);
+      }
+      return this;
+   }
+
+   public University withoutEmployees(Person value)
+   {
+      if (this.employees != null)
+      {
+         this.employees.remove(value);
+      }
+      return this;
+   }
+
+   public University withoutEmployees(Person... value)
+   {
+      for (final Person item : value)
+      {
+         this.withoutEmployees(item);
+      }
+      return this;
+   }
+
+   public University withoutEmployees(Collection<? extends Person> value)
+   {
+      for (final Person item : value)
+      {
+         this.withoutEmployees(item);
+      }
+      return this;
+   }
+
    public void removeYou()
    {
       this.withoutStudents(new ArrayList<>(this.getStudents()));
+      this.setPresident(null);
+      this.withoutEmployees(new ArrayList<>(this.getEmployees()));
    }
 }
 ```

src/main/java/org/fulib/builder/ClassModelManager.java

@@ -664,7 +664,7 @@ public AssocRole associate(Clazz srcClass, String srcRole, int srcSize, Clazz tg
     * @param srcSize
     *    the cardinality in the source class
     * @param tgtRole
-    *    the role name in the target class
+    *    the role name in the target class, or {@code null} to make the association unidirectional
     * @param tgtSize
     *    the cardinality in the target class
     *
@@ -691,7 +691,7 @@ public AssocRole haveRole(Clazz srcClass, String srcRole, Clazz tgtClass, int sr
     * @param tgtClass
     *    the target class
     * @param tgtRole
-    *    the role name in the target class
+    *    the role name in the target class, or {@code null} to make the association unidirectional
     * @param tgtSize
     *    the cardinality in the target class
     *
@@ -716,7 +716,7 @@ public AssocRole haveRole(Clazz srcClass, String srcRole, int srcSize, Clazz tgt
     * @param tgtClass
     *    the target class
     * @param tgtRole
-    *    the role name in the target class
+    *    the role name in the target class, or {@code null} to make the association unidirectional
     * @param tgtSize
     *    the cardinality in the target class
     *
@@ -726,6 +726,11 @@ public AssocRole haveRole(Clazz srcClass, String srcRole, int srcSize, Clazz tgt
     */
    public AssocRole associate(Clazz srcClass, String srcRole, int srcSize, Clazz tgtClass, String tgtRole, int tgtSize)
    {
+      if (srcRole == null)
+      {
+         throw new NullPointerException("srcRole must not be null");
+      }
+
       final AtomicBoolean modified = new AtomicBoolean(false);
 
       final AssocRole role = this.haveRole(srcClass, srcRole, srcSize, modified);

src/main/java/org/fulib/builder/ReflectiveClassBuilder.java

@@ -179,11 +179,18 @@ private static void loadAssoc(Field field, Link link, Clazz clazz, ClassModelMan
       final String name = field.getName();
       final CollectionType collectionType = getCollectionType(field.getType());
 
-      final String otherName = link.value();
+      String otherName = link.value();
+      if (otherName.isEmpty())
+      {
+         otherName = null;
+      }
 
       final Class<?> other = getOther(field, collectionType);
 
-      validateLinkTarget(field.getDeclaringClass(), name, otherName, other);
+      if (otherName != null)
+      {
+         validateLinkTarget(field.getDeclaringClass(), name, otherName, other);
+      }
 
       final String otherClazzName = other.getSimpleName();
       final Clazz otherClazz = manager.haveClass(otherClazzName);

src/main/java/org/fulib/builder/reflect/Link.java

@@ -16,6 +16,7 @@
 {
    /**
     * @return the name of the attribute in the other class.
+    * An omitted or empty value makes the association unidirectional.
     */
-   String value();
+   String value() default "";
 }

src/main/java/org/fulib/classmodel/AssocRole.java

@@ -132,7 +132,8 @@ public AssocRole setOther(AssocRole value)
    public String getId()
    {
       final Clazz clazz = this.getClazz();
-      return (clazz != null ? clazz.getName() : "_") + "_" + this.getName();
+      final String name = this.getName();
+      return (clazz != null ? clazz.getName() : "_") + "_" + (name != null ? name : this.getOther().getId());
    }
 
    public String getName()

src/main/java/org/fulib/classmodel/Clazz.java

@@ -529,6 +529,12 @@ public Clazz withoutAttributes(Collection<? extends Attribute> value)
 
    public AssocRole getRole(String name)
    {
+      if (name == null)
+      {
+         // searching for an anonymous role by name is nonsensical,
+         // especially since multiple of them can exist.
+         return null;
+      }
       for (AssocRole role : this.getRoles())
       {
          if (Objects.equals(role.getName(), name))

src/main/java/org/fulib/util/Generator4ClassFile.java

@@ -141,7 +141,7 @@ private void addDefaultImports(Clazz clazz, Set<String> qualifiedNames)
    {
       for (final AssocRole role : clazz.getRoles())
       {
-         if (role.isToMany())
+         if (role.getName() != null && role.isToMany())
          {
             this.addCollectionTypeImports(role.getCollectionType(), qualifiedNames);
          }

src/main/resources/org/fulib/templates/associations.javafx.stg

@@ -91,12 +91,16 @@ initMethod(role, other) ::= <<
          {
             for (final <other.clazz.name> value : change.getRemoved())
             {
+               <if(role.other.name)>
                value.<withoutThis(other)>;
+               <endif>
                this.firePropertyChange(PROPERTY_<role.name; format="upper_snake">, value, null);
             }
             for (final <other.clazz.name> value : change.getAddedSubList())
             {
+               <if(role.other.name)>
                value.<withThis(other)>;
+               <endif>
                this.firePropertyChange(PROPERTY_<role.name; format="upper_snake">, null, value);
             }
          }
@@ -105,6 +109,7 @@ initMethod(role, other) ::= <<
 <else>
       final import(javafx.beans.property.ObjectProperty)\<<other.clazz.name>\> result = new import(javafx.beans.property.SimpleObjectProperty)\<>();
       result.addListener((observable, oldValue, newValue) -> {
+         <if(role.other.name)>
          if (oldValue != null)
          {
             oldValue.<withoutThis(other)>;
@@ -113,6 +118,7 @@ initMethod(role, other) ::= <<
          {
             newValue.<withThis(other)>;
          }
+         <endif>
          this.firePropertyChange(PROPERTY_<role.name; format="upper_snake">, oldValue, newValue);
       });
       return result;

src/main/resources/org/fulib/templates/associations.pojo.stg

@@ -75,25 +75,25 @@ setMethod(role, other) ::= <<
 <endif>
    public <role.clazz.name> set<role.name; format="cap">(<other.clazz.name> value)
    {
+<if(other.name)>
       if (this.<role.name> == value)
       {
          return this;
       }
 
       final <other.clazz.name> oldValue = this.<role.name>;
-<if(other.name)>
       if (this.<role.name> != null)
       {
          this.<role.name> = null;
          oldValue.<withoutThis(other)>;
       }
-<endif>
       this.<role.name> = value;
-<if(other.name)>
       if (value != null)
       {
          value.<withThis(other)>;
       }
+<else>
+      this.<role.name> = value;
 <endif>
       return this;
    }
@@ -158,12 +158,17 @@ withoutItem(role, other) ::= <<
 <endif>
    public <role.clazz.name> without<role.name; format="cap">(<other.clazz.name> value)
    {
+<if(other.name)>
       if (this.<role.name> != null && this.<role.name>.remove(value))
       {
-<if(other.name)>
          value.<withoutThis(other)>;
-<endif>
       }
+<else>
+      if (this.<role.name> != null)
+      {
+         this.<role.name>.remove(value);
+      }
+<endif>
       return this;
    }
 >>

src/test/java/org/fulib/builder/ReflectiveClassBuilderTest.java

@@ -61,7 +61,11 @@ class University
       @Link("uni")
       List<Student> students;
 
+      @Link()
       Person president;
+
+      @Link()
+      List<Person> employees;
    }
 
    @Test
@@ -136,8 +140,15 @@ public void test()
       assertThat(uni.getCardinality(), is(Type.ONE));
       assertThat(uni.getCollectionType(), nullValue());
 
-      final Attribute president = university.getAttribute("president");
-      assertThat(president.getType(), equalTo("Person"));
+      final AssocRole president = university.getRole("president");
+      assertThat(president.getCardinality(), is(Type.ONE));
+      assertThat(president.getOther().getName(), nullValue());
+      assertThat(president.getOther().getClazz(), is(person));
+
+      final AssocRole employees = university.getRole("employees");
+      assertThat(employees.getCardinality(), is(Type.MANY));
+      assertThat(employees.getOther().getName(), nullValue());
+      assertThat(employees.getOther().getClazz(), is(person));
    }
 
    class StringList extends ArrayList<String>

src/test/java/org/fulib/generator/AssociationTest.java

@@ -6,17 +6,18 @@
 import org.fulib.builder.ClassModelBuilder;
 import org.fulib.builder.Type;
 import org.fulib.classmodel.ClassModel;
+import org.fulib.classmodel.CollectionType;
 import org.junit.jupiter.api.Test;
 
-import java.beans.PropertyChangeEvent;
-import java.beans.PropertyChangeListener;
 import java.io.File;
 import java.lang.reflect.Method;
 import java.net.URL;
 import java.net.URLClassLoader;
 import java.nio.file.Files;
 import java.nio.file.Paths;
-import java.util.*;
+import java.util.Arrays;
+import java.util.Collection;
+import java.util.Collections;
 
 import static org.hamcrest.CoreMatchers.*;
 import static org.hamcrest.MatcherAssert.assertThat;
@@ -79,24 +80,28 @@ protected void configureModel(ClassModelBuilder mb)
 
    protected final void buildModel(ClassModelBuilder mb)
    {
-      ClassBuilder universitiy = mb.buildClass("University").buildAttribute("name", Type.STRING);
-      // end_code_fragment:
-
+      ClassBuilder university = mb.buildClass("University").buildAttribute("name", Type.STRING);
       ClassBuilder studi = mb.buildClass("Student").buildAttribute("name", Type.STRING, "\"Karli\"");
-
-      universitiy.buildAssociation(studi, "students", Type.MANY, "uni", Type.ONE);
-
       ClassBuilder room = mb.buildClass("Room").buildAttribute("no", Type.STRING);
+      ClassBuilder assignment = mb.buildClass("Assignment").buildAttribute("topic", Type.STRING);
 
-      universitiy.buildAssociation(room, "rooms", Type.MANY, "uni", Type.ONE)
-                 .setSourceRoleCollection(LinkedHashSet.class).setAggregation();
+      // n to 1
+      university.buildAssociation(studi, "students", Type.MANY, "uni", Type.ONE);
 
-      studi.buildAssociation(room, "condo", Type.ONE, "owner", Type.ONE);
+      // n to 1 - custom collection type
+      university
+         .buildAssociation(room, "rooms", Type.MANY, "uni", Type.ONE)
+         .setSourceRoleCollection(CollectionType.LinkedHashSet)
+         .setAggregation();
 
+      // 1 to 1
+      studi.buildAssociation(room, "condo", Type.ONE, "owner", Type.ONE);
+      // n to n
       studi.buildAssociation(room, "in", Type.MANY, "students", Type.MANY);
 
-      ClassBuilder assignment = mb.buildClass("Assignment").buildAttribute("topic", Type.STRING);
-      studi.buildAssociation(assignment, "done", Type.MANY, "students", Type.MANY);
+      // unidirectional - the assignment does not need to know who did it
+      studi.buildAssociation(assignment, "workingOn", Type.ONE, null, 0);
+      studi.buildAssociation(assignment, "done", Type.MANY, null, 0);
    }
 
    protected void runDataTests(ClassLoader classLoader, String packageName) throws Exception