Play Framework 完整实现一个APP（六）

需要为Blog添加查看和发表评论的功能

1.创建查看功能

Application.java中添加 show() 方法

public static void show(Long id) {

    Post post = Post.findById(id);

    render(post);

}

创建 app/views/Application/show.html

#{extends 'main.html' /}

#{set title:post.title /}

#{display post:post, as:'full' /}

在页面模板中添加链接

访问Blog

<h2 class="post-title">

    <a href="@{Application.show(_post.id)}">${_post.title}</a>

</h2>

返回主页

<h1><a href="@{Application.index()}">${blogTitle}</a></h1>

2.创建路由规则

当前页面URL http://localhost:9000/application/show?id=3

是由 * /{controller}/{action} {controller}.{action} 这条规则解析得到的

在之前新创建Route

GET     /posts/{id}                             Application.show

访问路径变为 http://localhost:9000/posts/3

更多路由语法参考： http://play-framework.herokuapp.com/zh/routes#syntax

3.添加页导航

Post类添加方法，previous()\next()

public Post previous() {

    return Post.find("postedAt < ? order by postedAt desc", postedAt).first();

}

public Post next() {

    return Post.find("postedAt > ? order by postedAt asc", postedAt).first();

}

show.html页面添加导航按钮

<ul id="pagination">

    #{if post.previous()}

        <li id="previous">

            <a href="@{Application.show(post.previous().id)}">

                ${post.previous().title}

            </a>

        </li>

    #{/if}

    #{if post.next()}

        <li id="next">

            <a href="@{Application.show(post.next().id)}">

                ${post.next().title}

            </a>

        </li>

    #{/if}

</ul>

4.添加评论框

Application Controller添加方法postComment()

public static void postComment(Long postId, String author, String content) {

    Post post = Post.findById(postId);

    post.addComment(author, content);

    show(postId);

}

修改show.html

<h3>Post a comment</h3>

#{form @Application.postComment(post.id)}

    <p>

        <label for="author">Your name: </label>

        <input type="text" name="author" id="author" />

    </p>

    <p>

        <label for="content">Your message: </label>

        <textarea name="content" id="content"></textarea>

    </p>

    <p>

        <input type="submit" value="Submit your comment" />

    </p>

#{/form}

5.添加验证，验证Author和Content非空

import play.data.validation.*;

public static void postComment(Long postId, @Required String author, @Required String content) {

    Post post = Post.findById(postId);

    if (validation.hasErrors()) {

        render("Application/show.html", post);

    }

    post.addComment(author, content);

    show(postId);

}

编辑form，显示错误

#{form @Application.postComment(post.id)}

    #{ifErrors}

        <p class="error">

            All fields are required!

        </p>

    #{/ifErrors}

    <p>

        <label for="author">Your name: </label>

        <input type="text" name="author" id="author" value="${params.author}" />

    </p>

    <p>

        <label for="content">Your message: </label>

        <textarea name="content" id="content">${params.content}</textarea>

    </p>

    <p>

        <input type="submit" value="Submit your comment" />

    </p>

#{/form}

6.优化客户提示

加载jquery的类库

修改Show.html

#{if flash.success} 
　　<p class="success">${flash.success}</p> 
#{/if} 

#{display post:post, as:'full' /}

<script type="text/javascript" charset="utf-8">

    $(function() {

        // Expose the form

        $('form').click(function() {

            $('form').expose({api: true}).load();

        }); 

        // If there is an error, focus to form

        if($('form .error').size()) {

            $('form').expose({api: true, loadSpeed: 0}).load();

            $('form input[type=text]').get(0).focus();

        }

    });

</script>

添加Comment成功的提示

post.addComment(author, content);

flash.success("Thanks for posting %s", author);

添加路由

POST    /posts/{postId}/comments                Application.postComment

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Play Framework 完整实现一个APP（六）

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