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authorOndřej Surý <ondrej@sury.org>2011-02-14 13:23:51 +0100
committerOndřej Surý <ondrej@sury.org>2011-02-14 13:23:51 +0100
commit758ff64c69e34965f8af5b2d6ffd65e8d7ab2150 (patch)
tree6d6b34f8c678862fe9b56c945a7b63f68502c245 /doc/codelab/wiki/index.html
parent3e45412327a2654a77944249962b3652e6142299 (diff)
downloadgolang-upstream/2011-02-01.1.tar.gz
Imported Upstream version 2011-02-01.1upstream/2011-02-01.1
Diffstat (limited to 'doc/codelab/wiki/index.html')
-rw-r--r--doc/codelab/wiki/index.html117
1 files changed, 58 insertions, 59 deletions
diff --git a/doc/codelab/wiki/index.html b/doc/codelab/wiki/index.html
index c494a3ced..fe99c32d1 100644
--- a/doc/codelab/wiki/index.html
+++ b/doc/codelab/wiki/index.html
@@ -71,14 +71,14 @@ declaration.
<p>
Let's start by defining the data structures. A wiki consists of a series of
interconnected pages, each of which has a title and a body (the page content).
-Here, we define <code>page</code> as a struct with two fields representing
+Here, we define <code>Page</code> as a struct with two fields representing
the title and body.
</p>
<pre>
-type page struct {
- title string
- body []byte
+type Page struct {
+ Title string
+ Body []byte
}
</pre>
@@ -86,33 +86,33 @@ type page struct {
The type <code>[]byte</code> means "a <code>byte</code> slice".
(See <a href="http://golang.org/doc/effective_go.html#slices">Effective Go</a>
for more on slices.)
-The <code>body</code> element is a <code>[]byte</code> rather than
+The <code>Body</code> element is a <code>[]byte</code> rather than
<code>string</code> because that is the type expected by the <code>io</code>
libraries we will use, as you'll see below.
</p>
<p>
-The <code>page</code> struct describes how page data will be stored in memory.
+The <code>Page</code> struct describes how page data will be stored in memory.
But what about persistent storage? We can address that by creating a
-<code>save</code> method on <code>page</code>:
+<code>save</code> method on <code>Page</code>:
</p>
<pre>
-func (p *page) save() os.Error {
- filename := p.title + &#34;.txt&#34;
- return ioutil.WriteFile(filename, p.body, 0600)
+func (p *Page) save() os.Error {
+ filename := p.Title + &#34;.txt&#34;
+ return ioutil.WriteFile(filename, p.Body, 0600)
}
</pre>
<p>
This method's signature reads: "This is a method named <code>save</code> that
-takes as its receiver <code>p</code>, a pointer to <code>page</code> . It takes
+takes as its receiver <code>p</code>, a pointer to <code>Page</code> . It takes
no parameters, and returns a value of type <code>os.Error</code>."
</p>
<p>
-This method will save the <code>page</code>'s <code>body</code> to a text
-file. For simplicity, we will use the <code>title</code> as the file name.
+This method will save the <code>Page</code>'s <code>Body</code> to a text
+file. For simplicity, we will use the <code>Title</code> as the file name.
</p>
<p>
@@ -120,7 +120,7 @@ The <code>save</code> method returns an <code>os.Error</code> value because
that is the return type of <code>WriteFile</code> (a standard library function
that writes a byte slice to a file). The <code>save</code> method returns the
error value, to let the application handle it should anything go wrong while
-writing the file. If all goes well, <code>page.save()</code> will return
+writing the file. If all goes well, <code>Page.save()</code> will return
<code>nil</code> (the zero-value for pointers, interfaces, and some other
types).
</p>
@@ -137,17 +137,17 @@ We will want to load pages, too:
</p>
<pre>
-func loadPage(title string) *page {
+func loadPage(title string) *Page {
filename := title + &#34;.txt&#34;
body, _ := ioutil.ReadFile(filename)
- return &amp;page{title: title, body: body}
+ return &amp;Page{Title: title, Body: body}
}
</pre>
<p>
The function <code>loadPage</code> constructs the file name from
-<code>title</code>, reads the file's contents into a new
-<code>page</code>, and returns a pointer to that new <code>page</code>.
+<code>Title</code>, reads the file's contents into a new
+<code>Page</code>, and returns a pointer to that new <code>page</code>.
</p>
<p>
@@ -161,23 +161,23 @@ error return value (in essence, assigning the value to nothing).
<p>
But what happens if <code>ReadFile</code> encounters an error? For example,
the file might not exist. We should not ignore such errors. Let's modify the
-function to return <code>*page</code> and <code>os.Error</code>.
+function to return <code>*Page</code> and <code>os.Error</code>.
</p>
<pre>
-func loadPage(title string) (*page, os.Error) {
+func loadPage(title string) (*Page, os.Error) {
filename := title + &#34;.txt&#34;
body, err := ioutil.ReadFile(filename)
if err != nil {
return nil, err
}
- return &amp;page{title: title, body: body}, nil
+ return &amp;Page{Title: title, Body: body}, nil
}
</pre>
<p>
Callers of this function can now check the second parameter; if it is
-<code>nil</code> then it has successfully loaded a page. If not, it will be an
+<code>nil</code> then it has successfully loaded a Page. If not, it will be an
<code>os.Error</code> that can be handled by the caller (see the <a
href="http://golang.org/pkg/os/#Error">os package documentation</a> for
details).
@@ -191,17 +191,17 @@ written:
<pre>
func main() {
- p1 := &amp;page{title: &#34;TestPage&#34;, body: []byte(&#34;This is a sample page.&#34;)}
+ p1 := &amp;Page{Title: &#34;TestPage&#34;, Body: []byte(&#34;This is a sample Page.&#34;)}
p1.save()
p2, _ := loadPage(&#34;TestPage&#34;)
- fmt.Println(string(p2.body))
+ fmt.Println(string(p2.Body))
}
</pre>
<p>
After compiling and executing this code, a file named <code>TestPage.txt</code>
would be created, containing the contents of <code>p1</code>. The file would
-then be read into the struct <code>p2</code>, and its <code>body</code> element
+then be read into the struct <code>p2</code>, and its <code>Body</code> element
printed to the screen.
</p>
@@ -317,7 +317,7 @@ const lenPath = len(&#34;/view/&#34;)
func viewHandler(w http.ResponseWriter, r *http.Request) {
title := r.URL.Path[lenPath:]
p, _ := loadPage(title)
- fmt.Fprintf(w, &#34;&lt;h1&gt;%s&lt;/h1&gt;&lt;div&gt;%s&lt;/div&gt;&#34;, p.title, p.body)
+ fmt.Fprintf(w, &#34;&lt;h1&gt;%s&lt;/h1&gt;&lt;div&gt;%s&lt;/div&gt;&#34;, p.Title, p.Body)
}
</pre>
@@ -377,7 +377,7 @@ href="http://localhost:8080/view/test">http://localhost:8080/view/test</a></code
should show a page titled "test" containing the words "Hello world".
</p>
-<h2>Editing pages</h2>
+<h2>Editing Pages</h2>
<p>
A wiki is not a wiki without the ability to edit pages. Let's create two new
@@ -401,7 +401,7 @@ func main() {
<p>
The function <code>editHandler</code> loads the page
-(or, if it doesn't exist, create an empty <code>page</code> struct),
+(or, if it doesn't exist, create an empty <code>Page</code> struct),
and displays an HTML form.
</p>
@@ -410,14 +410,14 @@ func editHandler(w http.ResponseWriter, r *http.Request) {
title := r.URL.Path[lenPath:]
p, err := loadPage(title)
if err != nil {
- p = &amp;page{title: title}
+ p = &amp;Page{Title: title}
}
fmt.Fprintf(w, &#34;&lt;h1&gt;Editing %s&lt;/h1&gt;&#34;+
&#34;&lt;form action=\&#34;/save/%s\&#34; method=\&#34;POST\&#34;&gt;&#34;+
&#34;&lt;textarea name=\&#34;body\&#34;&gt;%s&lt;/textarea&gt;&lt;br&gt;&#34;+
&#34;&lt;input type=\&#34;submit\&#34; value=\&#34;Save\&#34;&gt;&#34;+
&#34;&lt;/form&gt;&#34;,
- p.title, p.title, p.body)
+ p.Title, p.Title, p.Body)
}
</pre>
@@ -454,10 +454,10 @@ Open a new file named <code>edit.html</code>, and add the following lines:
</p>
<pre>
-&lt;h1&gt;Editing {title}&lt;/h1&gt;
+&lt;h1&gt;Editing {Title}&lt;/h1&gt;
-&lt;form action=&#34;/save/{title}&#34; method=&#34;POST&#34;&gt;
-&lt;div&gt;&lt;textarea name=&#34;body&#34; rows=&#34;20&#34; cols=&#34;80&#34;&gt;{body|html}&lt;/textarea&gt;&lt;/div&gt;
+&lt;form action=&#34;/save/{Title}&#34; method=&#34;POST&#34;&gt;
+&lt;div&gt;&lt;textarea name=&#34;body&#34; rows=&#34;20&#34; cols=&#34;80&#34;&gt;{Body|html}&lt;/textarea&gt;&lt;/div&gt;
&lt;div&gt;&lt;input type=&#34;submit&#34; value=&#34;Save&#34;&gt;&lt;/div&gt;
&lt;/form&gt;
</pre>
@@ -472,7 +472,7 @@ func editHandler(w http.ResponseWriter, r *http.Request) {
title := r.URL.Path[lenPath:]
p, err := loadPage(title)
if err != nil {
- p = &amp;page{title: title}
+ p = &amp;Page{Title: title}
}
t, _ := template.ParseFile(&#34;edit.html&#34;, nil)
t.Execute(p, w)
@@ -486,15 +486,15 @@ The function <code>template.ParseFile</code> will read the contents of
<p>
The method <code>t.Execute</code> replaces all occurrences of
-<code>{title}</code> and <code>{body}</code> with the values of
-<code>p.title</code> and <code>p.body</code>, and writes the resultant
+<code>{Title}</code> and <code>{Body}</code> with the values of
+<code>p.Title</code> and <code>p.Body</code>, and writes the resultant
HTML to the <code>http.ResponseWriter</code>.
</p>
<p>
-Note that we've used <code>{body|html}</code> in the above template.
+Note that we've used <code>{Body|html}</code> in the above template.
The <code>|html</code> part asks the template engine to pass the value
-<code>body</code> through the <code>html</code> formatter before outputting it,
+<code>Body</code> through the <code>html</code> formatter before outputting it,
which escapes HTML characters (such as replacing <code>&gt;</code> with
<code>&amp;gt;</code>).
This will prevent user data from corrupting the form HTML.
@@ -511,11 +511,11 @@ While we're working with templates, let's create a template for our
</p>
<pre>
-&lt;h1&gt;{title}&lt;/h1&gt;
+&lt;h1&gt;{Title}&lt;/h1&gt;
-&lt;p&gt;[&lt;a href=&#34;/edit/{title}&#34;&gt;edit&lt;/a&gt;]&lt;/p&gt;
+&lt;p&gt;[&lt;a href=&#34;/edit/{Title}&#34;&gt;edit&lt;/a&gt;]&lt;/p&gt;
-&lt;div&gt;{body}&lt;/div&gt;
+&lt;div&gt;{Body}&lt;/div&gt;
</pre>
<p>
@@ -548,12 +548,12 @@ func editHandler(w http.ResponseWriter, r *http.Request) {
title := r.URL.Path[lenPath:]
p, err := loadPage(title)
if err != nil {
- p = &amp;page{title: title}
+ p = &amp;Page{Title: title}
}
renderTemplate(w, &#34;edit&#34;, p)
}
-func renderTemplate(w http.ResponseWriter, tmpl string, p *page) {
+func renderTemplate(w http.ResponseWriter, tmpl string, p *Page) {
t, _ := template.ParseFile(tmpl+&#34;.html&#34;, nil)
t.Execute(p, w)
}
@@ -568,8 +568,8 @@ The handlers are now shorter and simpler.
<p>
What if you visit <code>/view/APageThatDoesntExist</code>? The program will
crash. This is because it ignores the error return value from
-<code>loadPage</code>. Instead, if the requested page doesn't exist, it should
-redirect the client to the edit page so the content may be created:
+<code>loadPage</code>. Instead, if the requested Page doesn't exist, it should
+redirect the client to the edit Page so the content may be created:
</p>
<pre>
@@ -589,7 +589,7 @@ The <code>http.Redirect</code> function adds an HTTP status code of
header to the HTTP response.
</p>
-<h2>Saving pages</h2>
+<h2>Saving Pages</h2>
<p>
The function <code>saveHandler</code> will handle the form submission.
@@ -599,7 +599,7 @@ The function <code>saveHandler</code> will handle the form submission.
func saveHandler(w http.ResponseWriter, r *http.Request) {
title := r.URL.Path[lenPath:]
body := r.FormValue(&#34;body&#34;)
- p := &amp;page{title: title, body: []byte(body)}
+ p := &amp;Page{Title: title, Body: []byte(body)}
p.save()
http.Redirect(w, r, &#34;/view/&#34;+title, http.StatusFound)
}
@@ -607,7 +607,7 @@ func saveHandler(w http.ResponseWriter, r *http.Request) {
<p>
The page title (provided in the URL) and the form's only field,
-<code>body</code>, are stored in a new <code>page</code>.
+<code>Body</code>, are stored in a new <code>Page</code>.
The <code>save()</code> method is then called to write the data to a file,
and the client is redirected to the <code>/view/</code> page.
</p>
@@ -615,7 +615,7 @@ and the client is redirected to the <code>/view/</code> page.
<p>
The value returned by <code>FormValue</code> is of type <code>string</code>.
We must convert that value to <code>[]byte</code> before it will fit into
-the <code>page</code> struct. We use <code>[]byte(body)</code> to perform
+the <code>Page</code> struct. We use <code>[]byte(body)</code> to perform
the conversion.
</p>
@@ -634,7 +634,7 @@ First, let's handle the errors in <code>renderTemplate</code>:
</p>
<pre>
-func renderTemplate(w http.ResponseWriter, tmpl string, p *page) {
+func renderTemplate(w http.ResponseWriter, tmpl string, p *Page) {
t, err := template.ParseFile(tmpl+&#34;.html&#34;, nil)
if err != nil {
http.Error(w, err.String(), http.StatusInternalServerError)
@@ -660,7 +660,7 @@ Now let's fix up <code>saveHandler</code>:
<pre>
func saveHandler(w http.ResponseWriter, r *http.Request, title string) {
body := r.FormValue(&#34;body&#34;)
- p := &amp;page{title: title, body: []byte(body)}
+ p := &amp;Page{Title: title, Body: []byte(body)}
err := p.save()
if err != nil {
http.Error(w, err.String(), http.StatusInternalServerError)
@@ -725,7 +725,7 @@ the <code>Execute</code> method on the appropriate <code>Template</code> from
<code>templates</code>:
<pre>
-func renderTemplate(w http.ResponseWriter, tmpl string, p *page) {
+func renderTemplate(w http.ResponseWriter, tmpl string, p *Page) {
err := templates[tmpl].Execute(p, w)
if err != nil {
http.Error(w, err.String(), http.StatusInternalServerError)
@@ -747,7 +747,6 @@ Then we can create a global variable to store our validation regexp:
</p>
<pre>
-var titleValidator = regexp.MustCompile(&#34;^[a-zA-Z0-9]+$&#34;)
</pre>
<p>
@@ -761,7 +760,7 @@ the expression compilation fails, while <code>Compile</code> returns an
<p>
Now, let's write a function that extracts the title string from the request
-URL, and tests it against our <code>titleValidator</code> expression:
+URL, and tests it against our <code>TitleValidator</code> expression:
</p>
<pre>
@@ -807,7 +806,7 @@ func editHandler(w http.ResponseWriter, r *http.Request) {
}
p, err := loadPage(title)
if err != nil {
- p = &amp;page{title: title}
+ p = &amp;Page{Title: title}
}
renderTemplate(w, &#34;edit&#34;, p)
}
@@ -818,7 +817,7 @@ func saveHandler(w http.ResponseWriter, r *http.Request) {
return
}
body := r.FormValue(&#34;body&#34;)
- p := &amp;page{title: title, body: []byte(body)}
+ p := &amp;Page{Title: title, Body: []byte(body)}
err = p.save()
if err != nil {
http.Error(w, err.String(), http.StatusInternalServerError)
@@ -895,7 +894,7 @@ The closure returned by <code>makeHandler</code> is a function that takes
an <code>http.ResponseWriter</code> and <code>http.Request</code> (in other
words, an <code>http.HandlerFunc</code>).
The closure extracts the <code>title</code> from the request path, and
-validates it with the <code>titleValidator</code> regexp. If the
+validates it with the <code>TitleValidator</code> regexp. If the
<code>title</code> is invalid, an error will be written to the
<code>ResponseWriter</code> using the <code>http.NotFound</code> function.
If the <code>title</code> is valid, the enclosed handler function
@@ -936,14 +935,14 @@ func viewHandler(w http.ResponseWriter, r *http.Request, title string) {
func editHandler(w http.ResponseWriter, r *http.Request, title string) {
p, err := loadPage(title)
if err != nil {
- p = &amp;page{title: title}
+ p = &amp;Page{Title: title}
}
renderTemplate(w, &#34;edit&#34;, p)
}
func saveHandler(w http.ResponseWriter, r *http.Request, title string) {
body := r.FormValue(&#34;body&#34;)
- p := &amp;page{title: title, body: []byte(body)}
+ p := &amp;Page{Title: title, Body: []byte(body)}
err := p.save()
if err != nil {
http.Error(w, err.String(), http.StatusInternalServerError)