Clean up a bit
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Yann Esposito (Yogsototh)
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1 changed files with 49 additions and 35 deletions
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@ -200,7 +200,7 @@ Obviously:
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| `config/routes` | is where you'll configure the map %url → Code. |
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| `Handler/` | contains the files that will contain the code called when a %url is accessed. |
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| `templates/` | contains HTML, JS and %css templates. |
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| `templates/` | contains %html, js and %css templates. |
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| `config/models` | is where you'll configure the persistent objects (database tables). |
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During this tutorial we'll modify other files as well,
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@ -260,7 +260,7 @@ getEchoR theText = do
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Don't worry if you find all of this a bit cryptic.
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In short it just declare a function named `getEchoR` with one argument (`theText`) of type String.
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When this function is called, it return a `Handler RepHtml` whatever it is.
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But mainly this will encapsulate our expected result inside an HTML text.
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But mainly this will encapsulate our expected result inside an %html text.
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After saving the file, you should see yesod recompile the application.
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When the compilation is finished you'll see the message: `Starting devel application`.
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@ -284,7 +284,7 @@ A malicious user could not hide some bad script inside.
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This behavior is a direct consequence of _type safety_.
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The %url string is put inside a %url type.
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Then the interesting part in the %url is put inside a String type. To pass from %url type to String type some transformation are made. For example, replace all "`%20`" by space characters.
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Then to show the String inside an HTML document, the string is put inside an HTML type. Some transformations occurs like replace "<code><</code>" by "`<`".
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Then to show the String inside an %html document, the string is put inside an %html type. Some transformations occurs like replace "<code><</code>" by "`<`".
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Thanks to yesod, this tedious job is done for us.
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<code class="zsh">
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@ -292,7 +292,7 @@ Thanks to yesod, this tedious job is done for us.
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↓
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"some text<a>" :: String
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↓
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"some text <a>" :: HTML
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"some text <a>" :: Html
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</code>
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Yesod is not only fast, it helps us to remain secure.
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@ -480,10 +480,9 @@ postMirrorR = do
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Don't forget to declare it inside `yosog.cabal` and `Application.hs`.
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We will need to use the `reverse` function provided by `Data.Text` which explain the import.
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We will need to use the `reverse` function provided by `Data.Text` which explain the additional import.
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The only new thing here is the line that get the POST parameter named "content".
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If you want to know more detail about it and form in general you can take look at [the yesod book](http://www.yesodweb.com/book/forms).
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Create the two corresponding templates:
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@ -558,21 +557,12 @@ module Handler.Blog
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where
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import Import
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</code>
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To use Html in forms
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<code class="haskell">
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-- to use Html into forms
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import Yesod.Form.Nic (YesodNic, nicHtmlField)
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instance YesodNic Yosog
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</code>
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Define a form for adding a new article.
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Don't pay attention to all the syntax.
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If you are curious you can take a look at Applicative Functor.
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You just have to remember `areq` is for required form input.
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Its arguments being: `areq type label default_value`.
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<code class="haskell">
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entryForm :: Form Article
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entryForm = renderDivs $ Article
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@ -580,74 +570,98 @@ entryForm = renderDivs $ Article
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<*> areq nicHtmlField "Content" Nothing
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</code>
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This function defines a form for adding a new article.
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Don't pay attention to all the syntax.
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If you are curious you can take a look at Applicative Functor.
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You just have to remember `areq` is for required form input.
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Its arguments being: `areq type label default_value`.
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<code class="haskell">
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-- The view showing the list of articles
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getBlogR :: Handler RepHtml
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getBlogR = do
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-- Get the list of articles inside the database.
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articles <- runDB $ selectList [] [Desc ArticleTitle]
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-- We'll need the two "objects": entryWidget and enctype
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-- We'll need the two "objects": articleWidget and enctype
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-- to construct the form (see template/articles.hamlet).
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((_,entryWidget), enctype) <- generateFormPost entryForm
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((_,articleWidget), enctype) <- generateFormPost entryForm
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defaultLayout $ do
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$(widgetFile "articles")
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</code>
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Just take a look at the content of `template/articles.hamlet`.
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This handler should display a list of articles.
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We get the list from the DB and we construct the form.
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Just take a look at the corresponding template:
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<code class="html" file="articles.hamlet">
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<h1> Articles
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$if null articles
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-- <!-- Show a standard message if there is no article -->
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<p>There are no article.
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-- Show a standard message if there is no article
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<p>_{MsgNoEntries}
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$else
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-- <!-- Show the list of articles -->
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-- Show the list of articles
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<ul>
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$forall article <- articles
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<li>
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<a href=@{ArticleR (fst article)} > #{articleTitle (snd article)}
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<hr/>
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<hr/>
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<form method=post enctype=#{enctype}>
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^{articleWidget}
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<div>
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<input type=submit value="Post new article">
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</code>
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You should remark we added some logic inside the template.
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Now look at how to handle the creation of a new article.
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There is a test and a "loop".
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Another very interesting part is the creation of the form.
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The `articleWidget` was created by yesod.
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We have given him the right parameters (input required or optional, labels, default values).
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And now we have a protected form made for us.
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But we have to create the submit button.
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Get back to `Handler/Blog.hs`.
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<code class="haskell">
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-- we continue Handler/Blog.hs
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postBlogR :: Handler RepHtml
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postBlogR = do
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((res,entryWidget),enctype) <- runFormPost entryForm
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((res,articleWidget),enctype) <- runFormPost entryForm
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case res of
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FormSuccess article -> do
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articleId <- runDB $ insert article
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setMessageI $ MsgEntryCreated $ articleTitle article
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setMessage $ (articleTitle article) ++. " created"
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redirect RedirectPermanent $ ArticleR articleId
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_ -> defaultLayout $ do
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setTitleI MsgPleaseCorrectEntry
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setTitle "Please correct your entry form"
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$(widgetFile "articleAddError")
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where
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(++.) t s = toHtml $ T.append t (T.pack s)
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</code>
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This function should be used to create a new article.
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The `++.` is just a trick to make an append occurs within the right type.
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We handle the form response.
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If there is an error we go to an error message.
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For example if we left some required value blank.
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<code class="haskell">
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getArticleR :: ArticleId -> Handler RepHtml
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getArticleR articleId = do
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article <- runDB $ get404 articleId
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muser <- maybeAuth
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defaultLayout $ do
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setTitle $ toHtml $ articleTitle article
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$(widgetFile "article")
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</code>
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<div style="display:hidden">
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---
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<%= startTodo %>
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<ul>
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</li><li> Create a minimal blog system.
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</li><li> Use Authentification.
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<li> Use Authentification.
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</li>
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</ul>
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<%= endTodo %>
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</div>
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