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Editorial Team
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Asked: 2026-05-31T04:46:26+00:00

I am creating a simple blog web application using play framework, where there are

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I am creating a simple blog web application using play framework, where there are certain categories and users can post to the category they want, however the problem is that when i post to one category the post is posted to all categories as well.

Application code:
    import java.util.*;
    import models.*;
    public class Application extends Controller {
        public static void index() {
            List Posts = Post.find ("order by type desc").fetch();
            render(Posts); 
        }
        public static void addpost (String content) {
            Post post = new Post(content).save();

            renderJSON(content);
html code:                 
<h2>
        CollabBlog
    </h2>
#{extends 'main.html' /}
#{set title:'Home' /}
<head>
        <title>#{get 'title' /}</title>     
        <meta http-equiv="Content-Type" content="text/html; charset=utf-8"/>
        <link rel="stylesheet" type="text/css" media="screen" 
            href="@{'/public/stylesheets/categories.css'}" />        
    </head> 
<h3>Category: Health</h3>
#{ifnot Posts} 
    No posts to view
#{/ifnot}
<ul>
    #{list items:Posts, as: 'Post'}
    <li>        
        <p>${Post.poster}</p><p>${Post.content}</p>        
    </li>
    #{/list}
</ul>
<p>
    <a id="addpost" href="#">add new Health's post</a>    
</p>
<h3>Category: Politics</h3>
#{ifnot Posts} 
    No posts to view
#{/ifnot}
<ul>
    #{list items:Posts, as: 'Post'}
    <li>        
        <p>${Post.poster}:</p><p>${Post.content}</p>        
    </li>
    #{/list}
</ul>
<p>
    <a id="addpost" href="#">add new Politic's post</a>    
</p>
<h3>Category: Entertainment</h3>
#{ifnot Posts} 
    No posts to view
#{/ifnot}
<ul>
    #{list items:Posts, as: 'Post'}
    <li>        
        <p>${Post.poster}</p><p>${Post.content}</p>        
    </li>
    #{/list}
</ul>
<p>
    <a id="addpost" href="#">add new Entertainment's post</a>    
</p>
<body>
    <link href="index.css" rel="stylesheet" type="text/css">
</body>
<script type="text/javascript" charset="utf-8">
$('#addpost').click(function() {
    $.post('@{addpost()}', {content: prompt('post content ?')}, function(Post){
        $('ul').prepend()
    })
    $.post('@{addpost()}', {poster : prompt('which category ?')}, function(Post){
        $('ul').prepend()
    })   
})
</script>                
            }


        }

anyone knows how to solve this problem?

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1 Answer

  1. Editorial Team

    After reading your additional comments (and hopefully I haven’t misunderstood), what you could do in your controller is find all unique categories in your type column. Then for each type (as represented by the categories variable in the code snippet below) you could make this call:

    Map<String, List<Post>> map = new HashMap<String, List<Post>>();
// the categories variable here is the unique types from the Post table
for (String category : categories) {
    List<Post> posts = Post.find("type = ?", category).fetch();
    map.put(category, posts);
}
render(map);

    And then in your view, you can go over the keys of the map which will represent all the category names and then you get the value associated with the key and iterate over the posts for that category.

    The above assumes that the user can type in anything they want. If you actually want them to select just either Health, Politics and Entertainment as per your view example in your original post, then maybe you need to model categories in your database. Some options could be:

    First Option

    You could have two entities: (1) Post and (2) Category. The first you have. The second you will need to create. So create a Category entity like this:

    @Entity
public class Category extends Model {

    @OneToMany(mappedBy = "category", targetEntity = Post.class)
    public List<Post> posts;

    ...
}

    Then in your Post entity you can have a relationship between the Post and Category entities like this:

    @Entity
public class Post extends Model {

    @ManyToOne
    @JoinColumn(name = "category_id")
    public Category category;

    ...
}

    This would be good if a user (or you) could create categories dynamically (or directly in the database) to allow users to select pre-defined categories.

    Second Option

    If the above example is overkill because category is simply a word and doesn’t have other properties like description, then you could just use an enum for category:

    public class Post extends Model {

    @Enumerated(EnumType.STRING)
    public Category category;

    ...
}

    Where Category is an enum like this:

    public enum Category {
    HEALTH,
    ENTERTAINMENT,
    POLITICS
}

    Again this option means that the user would be selecting from a pre-defined list.

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