内容的延迟加载

Question

I have two entities : User and Post (relation one-to-many). Post fields: id , creationDate , title , content , user .

Data is stored in the database and accessed via Hibernate.

I have a controller to pass Post object as a JSON to JavaScript. Then it is shown on the web page. But it is not always necessary to pass all the Post fields. For ex., I need to show to the user only title and creation date, and if the user presses the button Show content , only then I need to show post content (which I want to request from server only when it is need to show).

So here is a problem: How can I implement lazy initialization of the content field in Post object? Should I write two methods in my controller: one for generating JSON with list of Posts and setting content field to null or empty String , and another to pass only content string?

Answer 1

Make post content an object and a single table in db.

It looks like the following in java:

public class Post {

  ...


  PostContent postContent;
}

Answer 2

First you may try to initialize the lazy collection at the DAO via Hibernate.initialize(lazyCollection) . If it didn't work then either use FetchType.EAGER or keep the session open during request and the collection should be fetched when needed.