Load related Applications/Categories when loading a BusinessObject

src/de/unipotsdam/cs/toolup/database/BusinessObjectFactory.java

 package de.unipotsdam.cs.toolup.database;
 
+import java.sql.SQLException;
+
 import de.unipotsdam.cs.toolup.model.Application;
 import de.unipotsdam.cs.toolup.model.BusinessObject;
 
 public class BusinessObjectFactory {
 
 	public static BusinessObject createBusinessObject(String id, String title,
-			String description) {
+			String description) throws SQLException {
 		int indexOfFirstSlash = id.indexOf('/');
 		String className =  id.substring(0, indexOfFirstSlash);
 		
 		switch (className.toLowerCase()){
-		case "application": return new Application(id, title, description);
-		case "category": return new Category(id, title, description);
+		case "application": return new Application(id, title, description, DatabaseController.loadRelatedCategoriesForApp(id));
+		case "category": return new Category(id, title, description, DatabaseController.loadRelatedApplicationsForCat(id));
 		case "feature": return new Feature(id, title, description);
 		default: throw new UnsupportedOperationException("No class defined for this prefix:" + className);
 		}

src/de/unipotsdam/cs/toolup/database/DatabaseController.java

@@ -5,6 +5,8 @@ import java.sql.DriverManager;
 import java.sql.ResultSet;
 import java.sql.SQLException;
 import java.sql.Statement;
+import java.util.HashSet;
+import java.util.Set;
 
 import de.unipotsdam.cs.toolup.model.BusinessObject;
 
@@ -29,4 +31,24 @@ public class DatabaseController {
 		return uuid.substring(0, indexOfFirstSlash);
 	}
 
+	public static Set<String> loadRelation(String tableName, String keyColumnName, String resultColumnName, String id) throws SQLException {
+		Connection connection = DriverManager.getConnection("jdbc:mysql://localhost:3306/test?user=root&pw=");
+		Statement statement = connection.createStatement();
+		String query = "SELECT * FROM " + tableName + " WHERE " + keyColumnName + " = '" + id + "';";
+		ResultSet res = statement.executeQuery(query);
+		Set<String> relatedIds = new HashSet<String>();
+		while (res.next()) {
+			relatedIds.add(res.getString(resultColumnName));
+		}
+		return relatedIds;
+	}
+
+	public static Set<String> loadRelatedCategoriesForApp(String id) throws SQLException {
+		return loadRelation("application_belongs_to_category", "application_uuid", "category_uuid", id);
+	}
+
+	public static Set<String> loadRelatedApplicationsForCat(String id) throws SQLException {
+		return loadRelation("application_belongs_to_category", "category_uuid", "application_uuid", id);
+	}
+
 }

src/de/unipotsdam/cs/toolup/model/Application.java

 package de.unipotsdam.cs.toolup.model;
 
+import java.util.Collection;
+import java.util.HashSet;
+import java.util.Set;
+
 public class Application extends BusinessObject {
 
-	public Application(String uuid, String title, String description) {
+	private final Collection<String> relatedCategories;
+
+	public Application(String uuid, String title, String description, Set<String> relatedCategories) {
 		super(uuid, title, description);
+		this.relatedCategories = relatedCategories;
+	}
+
+	public Collection<String> getRelatedCategories() {
+		return new HashSet<String>(this.relatedCategories);
 	}
 }

test/de/unipotsdam/cs/toolup/database/Category.java

 package de.unipotsdam.cs.toolup.database;
 
+import java.util.Collection;
+import java.util.HashSet;
+import java.util.Set;
+
 import de.unipotsdam.cs.toolup.model.BusinessObject;
 
 public class Category extends BusinessObject {
 
-	public Category(String uuid, String title, String description) {
+	private final Collection<String> relatedApplications;
+
+	public Category(String uuid, String title, String description, Set<String> relatedApplications) {
 		super(uuid, title, description);
+		this.relatedApplications = relatedApplications;
+	}
+
+	public Collection<String> getRelatedApplications() {
+		return new HashSet<String>(this.relatedApplications);
 	}
 
 }

test/de/unipotsdam/cs/toolup/database/DatabaseControllerTest.java

 package de.unipotsdam.cs.toolup.database;
 
 import static org.testng.AssertJUnit.assertEquals;
+import static org.testng.AssertJUnit.assertTrue;
 
 import java.sql.SQLException;
+import java.util.Arrays;
+import java.util.Collection;
 
 import org.testng.annotations.DataProvider;
 import org.testng.annotations.Test;
@@ -15,6 +18,11 @@ import de.unipotsdam.cs.toolup.model.BusinessObject;
 
 public class DatabaseControllerTest {
 	
+	private static final String FEATURE_TEST_ID_21 = "feature/test_id_21";
+	private static final String APPLICATION_TEST_ID_2 = "application/test_id_2";
+	private static final String APPLICATION_TEST_ID_1 = "application/test_id_1";
+	private static final String CATEGORY_TEST_ID_11 = "category/test_id_11";
+
 	@Test(dataProvider = PROVIDE_BUSINESS_OBJECTS)
 	public void testThatLoadedBusinessObjectHasExpectedValues(String expectedTitle, String expectedDescription, Class<? extends BusinessObject> expectedClass, String id) throws SQLException {
 		//arrange
@@ -41,10 +49,10 @@ public class DatabaseControllerTest {
 	public Object[][] provideBusinessObjects(){
 		return new Object[][]{
 				
-				{"Dropbox","Dropbox Description",Application.class,"application/test_id_1"},
-				{"Box.UP","Box.UP Description",Application.class,"application/test_id_2"},
-				{"Cloud Speicher","Cloud Speicher Description",Category.class,"category/test_id_11"},
-				{"Kalender anlegen","Kalender anlegen Description",Feature.class,"feature/test_id_21"}
+				{"Dropbox","Dropbox Description",Application.class,APPLICATION_TEST_ID_1},
+				{"Box.UP","Box.UP Description",Application.class,APPLICATION_TEST_ID_2},
+				{"Cloud Speicher","Cloud Speicher Description",Category.class,CATEGORY_TEST_ID_11},
+				{"Kalender anlegen","Kalender anlegen Description",Feature.class,FEATURE_TEST_ID_21}
 				
 		};
 	}
@@ -69,12 +77,36 @@ public class DatabaseControllerTest {
 	public Object[][] provideSampleIds(){
 		return new Object[][]{
 				
-				{"application","application/123456"},
-				{"feature","feature/123456"},
-				{"category","category/123456"}
+				{"application",APPLICATION_TEST_ID_1},
+				{"feature",FEATURE_TEST_ID_21},
+				{"category",CATEGORY_TEST_ID_11}
 				
 		};
 	}
 	
+	@Test
+	public void testThatLoadedCategoryHasRelatedApplications() throws SQLException {
+		//arrange
+		Collection<String> expectedAppIds = Arrays.asList(new String[] {APPLICATION_TEST_ID_1, APPLICATION_TEST_ID_2});
+
+		//act
+		Category cat = (Category) DatabaseController.load(CATEGORY_TEST_ID_11);
+
+		//assert
+		assertTrue(cat.getRelatedApplications().containsAll(expectedAppIds));
+	}
+	
+	@Test
+	public void testThatLoadedApplicationHasRelatedCategories() throws SQLException {
+		//arrange
+		Collection<String> expectedCatIds = Arrays.asList(new String[] {CATEGORY_TEST_ID_11});
+		
+		//act
+		Application app = (Application) DatabaseController.load(APPLICATION_TEST_ID_1);
+		
+		//assert
+		assertTrue(app.getRelatedCategories().containsAll(expectedCatIds));
+	}
+	
 
 }

test/de/unipotsdam/cs/toolup/model/ApplicationTest.java

@@ -12,10 +12,10 @@ public class ApplicationTest {
 	@Test
 	public void testThatAnApplicationDoesNotEqualAnOtherApplication() {
 		//arrange
-		BusinessObject anOtherApp = new Application(TEST_ID_1,null,null);
+		BusinessObject anOtherApp = new Application(TEST_ID_1,null,null, null);
 		
 		//act
-		BusinessObject newApp = new Application(TEST_ID_2,null,null);
+		BusinessObject newApp = new Application(TEST_ID_2,null,null, null);
 
 		//assert
 		assertFalse(anOtherApp.equals(newApp));
@@ -24,10 +24,10 @@ public class ApplicationTest {
 	@Test
 	public void testThatAnApplicationDoesEqualItself() {
 		//arrange
-		BusinessObject anOtherApp = new Application(TEST_ID_1,null,null);
+		BusinessObject anOtherApp = new Application(TEST_ID_1,null,null, null);
 		
 		//act
-		BusinessObject newApp = new Application(TEST_ID_1,null,null);
+		BusinessObject newApp = new Application(TEST_ID_1,null,null, null);
 		
 		//assert
 		assertTrue(anOtherApp.equals(newApp));