Content for Whom? — err.the

“Content for Whom?”

– Chris on January 08, 2007

Advertisement
Larry is building a personal home page. He’s using Ruby on Rails and fla-fla-flying. Why, at the rate he’s going, link groups and banner exchanges will be begging him to join in no time flat.

Just recently he was Googling and came across a post on Err the Blog titled Content for Whom? While the writer of said blog is a bit of a flake, Larry was able to make his site more dynamic and DRY using content_for after reading the post. Here’s how.

The Sidebar

We all know Rails compiles views before it compiles the layout. That is, if you set @page_title in your view, you may reference it in your layout. Something like <title>My Site :: <%= @page_title %></title>. content_for is no different: it allows you to ‘assign’ a chunk of HTML or Ruby to a symbol which may be referenced in your layout.
Here’s Larry’s layout:
```
<html>
<head><title>Larry's Personal Home Page</title></head>
<body>
  <table width="100%">
    <tr><td>
      <%= yield %>
    </td><td>
      <%= yield :sidebar %>
    </td></tr>
    <tr><td colspan="2" align="center">
      Copyright (c) 2006 Larry
    </td></tr>
  </table>
</body>
</html>
```
The first yield, clearly, will be replaced with Larry’s view when rendered. The second yield is a bit different: he’s passing it a symbol, saying he wants to yield :sidebar at that point in time—whatever :sidebar may be.
Let’s look at Larry’s view:
```
<font color="red">Welcome to my website.</font><br>
<img src="under_construction.gif"><br>
<font color="blue">It was coded by hand in notepad.</font><br>
<font color="green">Tell me what you <blink>think!!</blink></font><br>

<% content_for :sidebar do %>
  Hot Links<br>
  <a href="http://www.netscape.com">Netscape</a><br>
  <a href="http://www.lycos.com">Lycos</a><br>
  <a href="http://www.walmart.com">Wal Mart</a><br>
<% end %>
```
You got it, right? yield :sidebar is going to be replaced by whatever block is passed to content_for :sidebar. In this case, Larry’s sidebar.

Ah, solidarity:

That’s fairly useful, but it means Larry has to set :sidebar in every view if he wants one to always show up. A nice thing to do is provide a default.

The Conditional
Larry just needs to replace, in his layout,
```
<%= yield :sidebar %>
```
with
```
<%= (sidebar = yield :sidebar) ? sidebar : render(:partial => 'shared/sidebar') %>
```
Now shared/sidebar will always be rendered unless a view defines :sidebar with content_for. In those cirumstances the view’s :sidebar will be shown. So, you can override a default element of the layout. Nice.

As an aside, you can access @content_for_sidebar directly but that’s not legit. Deprecated.

The Faux Nested Layout

Imagine Larry has a whole bunch of controllers. He is happy with the default sidebar trick but there’s still an issue: he wants all the HomeController views to have a standard sidebar and all the UsersController to have a different standard sidebar.

One idea is to remove the shared/ from the conditional in his layout:
```
<%= (sidebar = yield :sidebar) ? sidebar : render(:partial => 'sidebar') %>
```
Now either home/_sidebar.rhtml or users/_sidebar.rhtml will be rendered depending on which controller you’re in. The problem is Larry loses his ‘catch-all’ default sidebar and is forced to create a _sidebar.rhtml file for every controller. Not cool.

I tell Larry, “Throw away that code and change it back to the conditional which uses shared/sidebar. Now, think about layouts. If you have a HomeController and home.rhtml exists in your views/layouts/ directory, Rails will render that. Perfect place to define a home-wide sidebar, yeah?”
views/layouts/home.rhtml:
```
<% content_for :sidebar do %>
  Cool Pages on My Site:<br>
  <a href="/home/lonely">LonelyGrrl Videos</a><br>
  <a href="/home/pagerank">My Google Pagerank</a><br>
  <a href="/home/web2">Web 2.0 Logo Generator (lol)</a>
<% end %>
<%= render :file => 'layouts/application' %>
```
This ‘layout’ file is setting :sidebar then rendering the application layout. Larry just needs to do the same thing for views/layouts/users.rhtml and he’s all set.

Let’s recap. Larry can now define content_for :sidebar in a view, define it for a whole set of controller views, and also have a site-wide default. All at the same time. Talk about power!

One caveat here is that content_for appends content. It don’t replace it. If you’re defining :sidebar in a view under views/home/, using the above example, you’re going to end up with what looks like two sidebars: the one in the home.rhtml layout file and the one in your specific view.

And hey, if you want real nested layouts there’s a plugin for Ruby on Rails available. So get that.

The Stylesheet

Years pass. Larry learns a bit of CSS and begins working for a big, corporate website. Special promotions are demanded by advertisers: they want to advertise on pages which have their own unique style with which “the kids” can identify. Something street. Like those PSP graffiti ads.

Larry, now a seasoned Rails pro, knows this is not a problem. content_for, after all. He comes up with this:
```
<html>
<head>
  <title>Big Corporate Website 4.0 Beta</title>
  <%= stylesheet_link_tag 'main' %>
  <%= yield :stylesheet %>
</head>
<body>
  <%= yield %>
</body>
</html>
```
See it? If there’s no content_for :stylesheet, everything works. The yield :sidebar just returns nil. However, Larry can also bust out a content_for :stylesheet in any view to add a bit more spice to that particular page. Like:
```
<% content_for :stylesheet do %>
  <%= stylesheet_link_tag 'railsconf' -%>
<% end %>

<h1>Welcome to our RailsConf information page!</h1>
```
Now his h1’s can be as nutty as all hell and won’t affect the other h1’s in his meticulously crafted website. He can even change the background color. Something pastel, I’d imagine.

The Fin

All of this content_for magic lovingly wraps ActionView’s capture method. The Rails API has the scoop. Just try to remember :layout is off limits when dealing with content_for. If you use it, you’ll just be messing with what gets displayed in your layout’s vanilla <%= yield %> call. Also heed this warning from the API docs: “Beware that content_for is ignored in caches. So you shouldnâ€™t use it for elements that are going to be fragment cached.”

The web’s really all about HTML, amirite? I dig the stuff Bruce is doing and hey, SimplyHelpful looks like a step in the right direction. My memories of Smarty are cherised, but ActionView has stolen my heart.

Glad to hear Larry learned CSS, those tables for layout in the first example were making me nervous!

(Great tips, too!)

Nicely done.

Interesting! I’d like to note one thing, though. Your code

<%= (sidebar = yield :sidebar) ? sidebar : render(:partial => 'shared/sidebar') %>

is a little bulky. You could just write

<%= yield :sidebar || render(:partial => 'shared/sidebar') %>

. Unless you’re using the sidebar content later on in the layout, you don’t need the conditional & assignment.

Hmm, looks like the Textile got a little screwed :(

Good post! Larry is my hero for today.

small comment to Peter’s post. The line should look like: <%= (yield :sidebar) || render(:partial => ‘shared/sidebar’) %>

What if the sidebar content is dynamic though, and needs to read from several different tables (models) regardless of which view is currently being shown. How should this data be prepared for the sidebar?

Jens in this case you put before_filter to controller that needs sidebar data for all (not necessary) actions (views).

Can you clarify this bit for me?

“Just try to remember :layout is off limits when dealing with content_for. If you use it, you’ll just be messing with what gets displayed in your layout’s vanilla <%= yield %>”

How would you go about overriding the layout for a particular method or class then? Say I have an default application layout defined, but also have 3 more layouts which might be used throughout the site, and I am using yield to load up sub layouts which contain the content_for blocks?

Nice post,I was keep looking for a solution to avoid having to add “content_for” in each view for the sidebar before came to your site.

I’wonder if there is any way to keep the sidebar unchanged for each session,that is to say,init only once,of course dynamic content,must I use ajax to render each view to a partical to archive this kind of behavior?

Thanks!

Calling yield on a nil value returns an empty string in rails 2.0, so you need to change the logic in your layouts that call yield to something like this:

<%= :sidebar ? (yield :sidebar) : render(:partial => ‘shared/sidebar’) %>

Thanks for this. Didn’t have a clue ‘til I read this page

The best article, thanks to the author. good jokes, funny jokes

Chris,

I know I'm late to this party, but you can't really check for existence of a Symbol like that, since the instant Ruby sees :sidebar the symbol exists. Fire up irb and try any number of conditionals:

:garbage_symbol_to_test ? ‘yes’ : ‘no’ => “yes”

Curses! Foiled again by my insistence on indentation in corresponence vs Textile.

Trying again:

I know I’m late to this party, but you can’t really check for existence of a Symbol like that, since the instant Ruby sees :sidebar the symbol exists. Fire up irb and try any number of conditionals:

:garbage_symbol_to_test ? ‘yes’ : ‘no’
=> “yes”

Tattoos Celtic Tattoos Lower Back Tattoos Dragon Tattoos Skull Tattoos Heart Tattoos Butterfly Tattoos Chinese Tattoos Layered Hair Styles Layered Hairstyles Emo Hairstyles Medium Hairstyles Bang Hairstyle Prom Hairstyle Hair Coloring Heart Lower Back Tattoos

I suggest 2 FLV Converter for Mac software. One is powerful in download YouTube Videos and convert downloaded FLV files; the other is professional in video converting, which can not only convert .flv video to all media formats, but also can convert all kinds of video formats to .flv, plus popular videos.

For anyone with old or elderly loved ones, it is important to take care of your central florida retirement communities brookdale senior living inc kelly home care services boston senior home care senior home care inc new jersey living will form new jersey living will senior day care centers florida golf retirement communities senior apartments in las vegas senior apartments las vegas in hopes making sure you or your old / elderly loved ones are taken care of with the best nursing care available.

sikiş porno sex video izle iyi porno uzun porno yeni pornolar porno seyret sex seyret porno filmler sex izleyin sex izle porno sex erotik porn video türk porno canlı porno porno izle porno porno film sex filmleri porn video porno film sex seyret porno video seyret orgazm porno seks izle erotik video sex videolar yetişkin video sex video izle porno video izle bedava porno 18 video seks porno sıcak izle yetişkin film sikiş seyret sex amatör videolar teen video erotik videolar yetişkin video yetişkin videolar pornolar porno video teen kızlık bozma sikiş sikiş video seks türban sex sex erotik seks izle sıcak ateşli

modern abstract art sofa manufacturer гранит 净水器混合机过滤机 DHL快递保险箱法兰法兰标准牛皮癣皮肤病北京快递公司北京国际快递传世私服传奇世界私服天龙八部私服天龙私服网络电话免费网络电话假发补发织发植发上海搬家公司上海搬场公司大众搬家大众搬场张家界旅游香港旅游深圳旅行社打包机收缩机萎缩性胃炎 neoprene laptop bags SEO优化 SEO优化计量泵胃炎胃病冷水机冰水机工业冷水机油罐车油罐车油罐车油罐车油罐车油罐车油罐车油罐车油罐车油罐车油罐车油罐车油罐车油罐车油罐车油罐车油罐车油罐车油罐车油罐车油罐车北京办证办证北京特价机票北京打折计票北京国际机票北京机票预定北京飞机票北京订机票北京机票查询血糖仪血糖仪银杏水培花卉企业宣传片空分设备机电设备安装代孕代孕网代孕代孕代孕试管婴儿代孕电话交换机程控交换机集团电话集装袋混合机混合机混合机捏合机捏合机捏合机导热油炉导热油炉导热油炉反应釜反应釜反应釜回流焊波峰焊 spherical roller bearing 搬运车搬运车电动搬运车油桶搬运车堆高车电动堆高车半电动堆高车堆垛车高空作业平台车电动叉车平衡重叉车前移叉车电瓶叉车苗木价格苗木信息标牌制作深圳标牌儿童摄影北京儿童摄影防静电鞋淘宝刷信誉威海凤凰湖威海海景房大庆密封件打标机淘宝刷信誉 TESOL/TEFL国际英语教师证书英语教师进修及培训韩国饰品批发代写论文代写论文代写论文代写代发论文代写电源模块模块电源 X架超薄灯箱> 易拉宝展柜制作代理服务器游戏加速器网络加速器网通加速器电信加速器电信网通转换器电信网通加速器网通电信互转网通电信互通网络游戏加速器美国VPN代理美国独享VPN 美国独享IP pvc ceiling panel Spherical roller bearings 天龙八部私服 SEO优化安全鞋劳保鞋防砸鞋电绝缘鞋上海安全鞋上海劳保鞋江苏劳保鞋服装软件服装管理软件进销存软件进销存管理软件服装管理系统服装进销存软件进销存系统进销存管理系统免费进销存软件吉林中医东北特产打包机 dhl 阳痿阴茎短小阴茎增大早泄前列腺炎阴茎增粗阴茎延长国际机票上海国际机票国际打折机票国际特价机票 CRM 客户管理软件客户关系管理免费客户管理软件客户管理软件下载客户信息管理系统销售管理系统销售管理 CRM系统 CRM软件客户关系管理系统客户关系管理软件客户管理客户管理系统营销管理系统客户资源管理销售管理软件客户资料管理软件客户资源管理软件客户信息管理软件客户资料管理客户资源管理客户信息管理客户资料管理系统客户资源管理系统客户管理软件免费版砂磨机砂磨机砂磨机卧式砂磨机卧式砂磨机卧式砂磨机三辊研磨机三辊研磨机三辊研磨机混合机混合机混合机锥形混合机锥形混合机锥形混合机行星动力混合机行星动力混合机行星动力混合机无重力混合机无重力混合机无重力混合机干粉砂浆设备干粉砂浆设备干粉砂浆设备捏合机捏合机捏合机导热油炉导热油炉导热油炉反应釜反应釜反应釜搪玻璃反应釜搪玻璃反应釜搪玻璃反应釜乳化机涂料设备干混砂浆设备无重力混合机胶体磨涂料成套设备双螺旋混合机北京婚庆北京婚庆公司 400电话办证呼吸机制氧机亚都亚都加湿器亚都净化器亚都装修卫士饰品批发小饰品批发韩国饰品韩国饰品批发 premature ejaculation penis enlargement 破碎机制砂机球磨机雷蒙磨雷蒙磨粉机鄂式破碎机鄂式破碎机免烧砖机加气混凝土设备反击式破碎机选矿设备安利产品马来西亚留学网站优化网站推广衬布代写论文代写论文代写论文论文代写代写论文代写硕士论文代写毕业论文磁力泵离心泵化工泵隔膜泵螺杆泵潜水泵油泵耐腐蚀泵泵水泵拖链防护罩排屑机塑料拖链钢铝拖链水泵磁力泵隔膜泵离心泵液下泵自吸泵多级泵排污泵螺杆泵油泵化工泵电动隔膜泵气动隔膜泵自吸式磁力泵氟塑料磁力泵管道离心泵导热油泵深井泵潜水泵污水泵潜水排污泵深圳装饰深圳装饰公司深圳装修公司特价机票打折机票国际机票机票新风换气机换气机立式新风换气机风机箱新风系统能量回收机搅拌机混合机乳化机分散机毛刷毛刷辊工业毛刷刷子钢丝刷涂层测厚仪硬度计兆欧表激光测距仪测振仪转速表温湿度计风速仪超声波测厚仪粗糙度仪噪音计红外测温仪万用表硬度计万用表美容院美容加盟澳洲留学澳大利亚留学什么是法兰电烤箱酒店预定北京酒店预定北京酒店离心机 nail equipment nail products nail product nail uv lamp nail uv lamp nail uv lamps uv nail lamp nail brush nail file nail tool nail tip nail gel curing uv lamps lights 万用表风速仪红外测温仪噪音计

情趣用品,情趣用品,情趣用品,情趣用品,情趣用品,情趣,情趣,情趣,情趣,情人歡愉用品,情惑用品性哥,情人用品性哥,情趣用品,AIO交友愛情館,情人歡愉用品,美女視訊,情色交友,情人用品性哥,視訊交友,辣妹視訊,美女交友,性愛,嘟嘟成人網,按摩棒,震動按摩棒,微調按摩棒,情趣按摩棒,逼真按摩棒,G點,跳蛋,跳蛋,跳蛋,性感內衣,飛機杯,充氣娃娃,情趣娃娃,角色扮演,性感睡衣,後庭區,SM,潤滑液,情趣禮物,威而柔,香水,精油,芳香精油,自慰,自慰套,性感吊帶襪,情趣用品加盟,情人節禮物,情人節,吊帶襪,辣妹視訊,美女交友,情色交友,成人交友,視訊聊天室,美女視訊,視訊美女,情色視訊,免費視訊聊天,視訊交友,視訊聊天,AIO交友愛情館,嘟嘟成人網,成人貼圖,成人網站,AIO交友愛情館,情色,情色貼圖,情色文學,情色交友,色情聊天室,色情小說,七夕情人節,色情,A片,A片下載,免費A片,免費A片下載,情色視訊,情色電影,色情網站,辣妹視訊,視訊聊天室,情色視訊,免費視訊聊天,視訊聊天,美女視訊,視訊美女,美女交友,美女,情色交友,成人交友,自拍,本土自拍,情人視訊網,視訊交友90739,生日禮物,情色論壇,正妹牆,正妹,成人網站,A片,免費A片,A片下載,免費A片下載,AV女優,成人影片,色情A片,成人論壇,情趣,免費成人影片,成人電影,成人影城,愛情公寓,色情影片,保險套

Thanks so much for this! This is exactly what I was looking for

mirc mırc mırç mirç mirc indir mirc yükle mirc yukle türkçe mirc mirc indir mirc islami sohbet kelebek kelebek script kelebek sohbet kelebek mirc chat çet cet çet odaları sohbet kanalları sohbet odaları kameralı sohbet kameralı chat sohbet eğlence mirc sohbet odaları sevgili arkadaş arkadaş bul arkaraş ara oto araba şarkı sözleri astroloji ikinci el telefon gazete gazeteler günlük gazeteler marifetname bedava domain ücretsiz domain benimurl parça kontör parça kontör radyo dinle bedava blog ücretsiz blog

Victorias Secret Victoria’s Secret Fashion show Victorias Secret Pink Victorias Secret Model Victorias Secret Credit Card Victorias Secret Coupon Code Victorias Secret Lingerie Victorias Secret Fashion Show 2005 Victorias Secret Fashion Show 2006 Victorias Secret Bra Victorias Secret Catalog Victorias Secret Pantie Victorias Secret Online Coupon Victorias Secret Fashion Show 2007 Victorias Secret Girl Free Shipping Victorias Secret Victorias Secret Home Victorias Secret Christmas Victoria’S Secret Pink Dog Victorias Secret Music Victorias Secret Semi Annual Sale Victorias Secret Jobs Victorias Secret Free Shipping Code Victorias Secret Shoes Victorias Secret Thong Victorias Secret Commercial Victorias Secret Promotional Code Victorias Secret Love Spell Victorias Secret Boots Victorias Secret Employment Victorias Secret Reviews Victorias Secret Jeans Victorias Secret Brasil Victorias Secret Bag

情人用品,情人用品性哥,情人用品,情趣用品,視訊交友,視訊美女,視訊美女,視訊交友網,視訊聊天室,視訊聊天室,視訊交友網,免費視訊聊天,辣妹視訊,辣妹視訊,情人視訊網

徵信社,案件討論,男女專區,法律諮詢,相關新聞,情趣用品,情趣用品,情趣精品,情趣用品,情趣用品,情趣用品,情趣用品,威而柔,自慰套,自慰套,SM,充氣娃娃,充氣娃娃,潤滑液,飛機杯,按摩棒,跳蛋,性感睡衣

威而柔,自慰套,自慰套,SM,充氣娃娃,充氣娃娃,潤滑液,飛機杯,按摩棒,跳蛋,性感睡衣,視訊交友90739,情人視訊網,情色交友,視訊交友,辣妹視訊,美女視訊,aio交友愛情館,情色論壇,成人論壇,免費視訊聊天,辣妹視訊,視訊交友網,美女視訊,視訊交友,成人視訊,情趣用品,成人聊天室,情趣,情趣,視訊聊天室,視訊聊天,視訊聊天室,情色視訊,情人視訊網,免費視訊聊天室,aio交友愛情館,色情遊戲,寄情築園小遊戲,情色文學,一葉情貼圖片區

:-)))) Very interesting! Thanks!!!

The Sidebar

The Conditional

The Faux Nested Layout

The Stylesheet

The Fin