[英]LazyInitializationException in playframework
在為使用playframework
Web應用編寫功能測試時,我創建了
@Before
public void setup() {
Fixtures.deleteDatabase();
}
@Test
public void testListTagged() {
Fixtures.loadModels("data.yml");
Response response = GET("/books/category/science");
assertNotNull(renderArgs("books"));
List<Book> books = (List<Book>)renderArgs("books");
assertEquals(3,books.size());
listTagged
方法檢查Cache
是否有包含屬於給定類別的書籍列表的地圖對象( String:List<Book>
),如果地圖為null或列表為null,則進行數據庫查詢,並且列表為呈現為“書籍”。
public static void listTagged(String category) {
List<Book> books =null;
Map<String,List<Book>> tagMap = (Map<String, List<Book>>) Cache.get("tagmap");
if(tagMap!= null) {
books = tagMap.get(category);
}
if(tagMap==null || books == null) {
books= Book.findTaggedWith(category);
}
Book book = null;
if (books!=null && books.size()>0) {
book = books.get(0);
}
render(category,book, books);
}
圖書類為
@Entity
public class Book extends Model implements Comparable<Book>{
@Required
@Column(unique = true)
public String isbn;
@Required
//@Field
public String name;
...
@ManyToMany(cascade=CascadeType.PERSIST)
public Set<Category> categories;
public Book(String isbn, String name, ...) {
super();
this.isbn = isbn;
this.name = name;
...
this.categories = new TreeSet<Category>();
}
...
public static List<Book> findTaggedWith(String categoryName) {
Map<String,List<Book>> tagMap = (Map<String, List<Book>>) Cache.get("tagmap");
if(tagMap==null) {
tagMap= new HashMap<String,List<Book>>();
}
List<Book> books = Book.find("select distinct book from Book book join book.categories as cat where cat.name=:name").bind("name", categoryName).fetch();
tagMap.put(categoryName, books);
Cache.add("tagmap", tagMap,"20mn");
return books;
}
單獨運行上面的測試不會造成任何問題,但是當它與一些單元測試一起運行時,這些單元測試調用了各種書籍的數據庫會導致延遲初始化異常
A java.lang.RuntimeException has been caught, java.util.concurrent.ExecutionException: play.exceptions.TemplateExecutionException: failed to lazily initialize a collection of role: models.Book.categories, no session or session was closed
我該如何解決? 有人可以請教嗎?
您可以使用:
@ManyToMany(cascade=CascadeType.PERSIST, fetch=FetchType.EAGER)
public Set<Category> categories;
這可能會解決問題。 否則,您必須要注意,會話已打開。 經過測試,現在可以工作
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