394 lines
22 KiB
Plaintext
Generated
394 lines
22 KiB
Plaintext
Generated
<!DOCTYPE html>
|
|
<html>
|
|
<head>
|
|
<meta charset="utf-8">
|
|
<title>Go by Example: Templates</title>
|
|
<link rel=stylesheet href="site.css">
|
|
</head>
|
|
<script>
|
|
onkeydown = (e) => {
|
|
|
|
if (e.key == "ArrowLeft") {
|
|
window.location.href = 'regular-expressions';
|
|
}
|
|
|
|
|
|
if (e.key == "ArrowRight") {
|
|
window.location.href = 'json';
|
|
}
|
|
|
|
}
|
|
</script>
|
|
<body>
|
|
<div class="example" id="templates">
|
|
<h2><a href="./">Go by Example</a>: Templates</h2>
|
|
|
|
<table>
|
|
|
|
<tr>
|
|
<td class="docs">
|
|
<p>Go offers built-in support for creating
|
|
dynamic content or showing customized output to the user called Template.</p>
|
|
|
|
</td>
|
|
<td class="code empty leading">
|
|
|
|
|
|
</td>
|
|
</tr>
|
|
|
|
<tr>
|
|
<td class="docs">
|
|
|
|
</td>
|
|
<td class="code leading">
|
|
<a href="http://play.golang.org/p/6tbag7ghomI"><img title="Run code" src="play.png" class="run" /></a><img title="Copy code" src="clipboard.png" class="copy" />
|
|
<pre class="chroma"><span class="kn">package</span> <span class="nx">main</span>
|
|
</pre>
|
|
</td>
|
|
</tr>
|
|
|
|
<tr>
|
|
<td class="docs">
|
|
<p>Go has two template packages. one is “text/template” for
|
|
regular text manipulation, and another one is “html/template”.
|
|
“html/template” has the same API as text/template which has additional security features.
|
|
It should be used when generating HTML
|
|
Here we show some of “text/template” features.</p>
|
|
|
|
</td>
|
|
<td class="code leading">
|
|
|
|
<pre class="chroma">
|
|
<span class="kn">import</span> <span class="p">(</span>
|
|
<span class="s">"os"</span>
|
|
<span class="s">"text/template"</span>
|
|
<span class="p">)</span>
|
|
</pre>
|
|
</td>
|
|
</tr>
|
|
|
|
<tr>
|
|
<td class="docs">
|
|
|
|
</td>
|
|
<td class="code leading">
|
|
|
|
<pre class="chroma"><span class="kd">func</span> <span class="nf">main</span><span class="p">()</span> <span class="p">{</span>
|
|
</pre>
|
|
</td>
|
|
</tr>
|
|
|
|
<tr>
|
|
<td class="docs">
|
|
<p>New creates a template with a specific name and returns a pointer to it.</p>
|
|
|
|
</td>
|
|
<td class="code leading">
|
|
|
|
<pre class="chroma">
|
|
<span class="nx">t</span> <span class="o">:=</span> <span class="nx">template</span><span class="p">.</span><span class="nf">New</span><span class="p">(</span><span class="s">"my-template"</span><span class="p">)</span>
|
|
</pre>
|
|
</td>
|
|
</tr>
|
|
|
|
<tr>
|
|
<td class="docs">
|
|
<p>Parse parses its parameter as template body.
|
|
We use {{.}} to access the value passed to the template when it’s getting executed.</p>
|
|
|
|
</td>
|
|
<td class="code leading">
|
|
|
|
<pre class="chroma">
|
|
<span class="nx">t</span><span class="p">,</span> <span class="nx">_</span> <span class="p">=</span> <span class="nx">t</span><span class="p">.</span><span class="nf">Parse</span><span class="p">(</span><span class="s">"Value is {{.}}\n"</span><span class="p">)</span>
|
|
</pre>
|
|
</td>
|
|
</tr>
|
|
|
|
<tr>
|
|
<td class="docs">
|
|
<p>If we want to ignore the errors we can use Must function.
|
|
It will panic if an error occurs when parsing the template.</p>
|
|
|
|
</td>
|
|
<td class="code leading">
|
|
|
|
<pre class="chroma">
|
|
<span class="nx">t</span> <span class="p">=</span> <span class="nx">template</span><span class="p">.</span><span class="nf">Must</span><span class="p">(</span><span class="nx">t</span><span class="p">.</span><span class="nf">Parse</span><span class="p">(</span><span class="s">"Value is {{.}}\n"</span><span class="p">))</span>
|
|
</pre>
|
|
</td>
|
|
</tr>
|
|
|
|
<tr>
|
|
<td class="docs">
|
|
<p>Execute applies parsed template to the data we pass to it and writes the output to the io.Writer.</p>
|
|
|
|
</td>
|
|
<td class="code leading">
|
|
|
|
<pre class="chroma">
|
|
<span class="nx">t</span><span class="p">.</span><span class="nf">Execute</span><span class="p">(</span><span class="nx">os</span><span class="p">.</span><span class="nx">Stdout</span><span class="p">,</span> <span class="nx">t</span><span class="p">.</span><span class="nf">Name</span><span class="p">())</span>
|
|
<span class="nx">t</span><span class="p">.</span><span class="nf">Execute</span><span class="p">(</span><span class="nx">os</span><span class="p">.</span><span class="nx">Stdout</span><span class="p">,</span> <span class="s">"some text"</span><span class="p">)</span>
|
|
<span class="nx">t</span><span class="p">.</span><span class="nf">Execute</span><span class="p">(</span><span class="nx">os</span><span class="p">.</span><span class="nx">Stdout</span><span class="p">,</span> <span class="kc">true</span><span class="p">)</span>
|
|
<span class="nx">t</span><span class="p">.</span><span class="nf">Execute</span><span class="p">(</span><span class="nx">os</span><span class="p">.</span><span class="nx">Stdout</span><span class="p">,</span> <span class="mi">5</span><span class="p">)</span>
|
|
<span class="nx">t</span><span class="p">.</span><span class="nf">Execute</span><span class="p">(</span><span class="nx">os</span><span class="p">.</span><span class="nx">Stdout</span><span class="p">,</span> <span class="p">[]</span><span class="kt">string</span><span class="p">{</span>
|
|
<span class="s">"Go"</span><span class="p">,</span>
|
|
<span class="s">"Rust"</span><span class="p">,</span>
|
|
<span class="s">"C++"</span><span class="p">,</span>
|
|
<span class="s">"C#"</span><span class="p">,</span>
|
|
<span class="p">})</span>
|
|
<span class="nx">t</span><span class="p">.</span><span class="nf">Execute</span><span class="p">(</span><span class="nx">os</span><span class="p">.</span><span class="nx">Stdout</span><span class="p">,</span> <span class="kd">struct</span><span class="p">{</span> <span class="nx">name</span> <span class="kt">string</span> <span class="p">}{</span>
|
|
<span class="nx">name</span><span class="p">:</span> <span class="s">"Arash"</span><span class="p">,</span>
|
|
<span class="p">})</span>
|
|
</pre>
|
|
</td>
|
|
</tr>
|
|
|
|
<tr>
|
|
<td class="docs">
|
|
<p>If the data is a struct we can use the {{.FieldName}} action to access its fields.
|
|
The fields should be exported to be accessible when template is executing.</p>
|
|
|
|
</td>
|
|
<td class="code leading">
|
|
|
|
<pre class="chroma">
|
|
<span class="nx">t</span><span class="p">,</span> <span class="nx">_</span> <span class="p">=</span> <span class="nx">t</span><span class="p">.</span><span class="nf">Parse</span><span class="p">(</span><span class="s">"Firstname: {{.Firstname}}"</span> <span class="o">+</span>
|
|
<span class="s">", Lastname: {{.Lastname}}\n"</span><span class="p">)</span>
|
|
</pre>
|
|
</td>
|
|
</tr>
|
|
|
|
<tr>
|
|
<td class="docs">
|
|
|
|
</td>
|
|
<td class="code leading">
|
|
|
|
<pre class="chroma"> <span class="nx">t</span><span class="p">.</span><span class="nf">Execute</span><span class="p">(</span><span class="nx">os</span><span class="p">.</span><span class="nx">Stdout</span><span class="p">,</span> <span class="kd">struct</span> <span class="p">{</span>
|
|
<span class="nx">Firstname</span><span class="p">,</span> <span class="nx">Lastname</span> <span class="kt">string</span>
|
|
<span class="p">}{</span>
|
|
<span class="nx">Firstname</span><span class="p">:</span> <span class="s">"Arash"</span><span class="p">,</span>
|
|
<span class="nx">Lastname</span><span class="p">:</span> <span class="s">"Sameni"</span><span class="p">,</span>
|
|
<span class="p">})</span>
|
|
</pre>
|
|
</td>
|
|
</tr>
|
|
|
|
<tr>
|
|
<td class="docs">
|
|
<p>Samething applies for maps. But it’s not necessary to have uppercase fields.</p>
|
|
|
|
</td>
|
|
<td class="code leading">
|
|
|
|
<pre class="chroma">
|
|
<span class="nx">t</span><span class="p">.</span><span class="nf">Execute</span><span class="p">(</span><span class="nx">os</span><span class="p">.</span><span class="nx">Stdout</span><span class="p">,</span> <span class="kd">map</span><span class="p">[</span><span class="kt">string</span><span class="p">]</span><span class="kt">string</span><span class="p">{</span>
|
|
<span class="s">"Firstname"</span><span class="p">:</span> <span class="s">"Robert"</span><span class="p">,</span>
|
|
<span class="s">"Lastname"</span><span class="p">:</span> <span class="s">"Griesemer"</span><span class="p">,</span>
|
|
<span class="p">})</span>
|
|
</pre>
|
|
</td>
|
|
</tr>
|
|
|
|
<tr>
|
|
<td class="docs">
|
|
<p>You can use if control structure to show data conditionally.
|
|
The data between if block will be shown if the field is truthy.
|
|
Means it is not false boolean, empty string, nil or zero length slice, nil map/pointer.</p>
|
|
|
|
</td>
|
|
<td class="code leading">
|
|
|
|
<pre class="chroma">
|
|
<span class="nx">t</span><span class="p">,</span> <span class="nx">_</span> <span class="p">=</span> <span class="nx">t</span><span class="p">.</span><span class="nf">Parse</span><span class="p">(</span><span class="s">`</span><span class="cp">{{</span><span class="k">if</span><span class="w"> </span><span class="na">.Field1</span><span class="cp">}}</span><span class="s">
|
|
</span><span class="s"> If block => </span><span class="cp">{{</span><span class="na">.Field1</span><span class="cp">}}</span><span class="s">
|
|
</span><span class="s"> </span><span class="cp">{{</span><span class="w"> </span><span class="k">else</span><span class="w"> </span><span class="k">if</span><span class="w"> </span><span class="na">.Field2</span><span class="cp">}}</span><span class="s">
|
|
</span><span class="s"> Else if block => </span><span class="cp">{{</span><span class="na">.Field2</span><span class="cp">}}</span><span class="s">
|
|
</span><span class="s"> </span><span class="cp">{{</span><span class="w"> </span><span class="k">else</span><span class="w"> </span><span class="cp">}}</span><span class="s">
|
|
</span><span class="s"> Else block
|
|
</span><span class="s"> </span><span class="cp">{{</span><span class="w"> </span><span class="k">end</span><span class="w"> </span><span class="cp">}}</span><span class="s">`</span><span class="p">)</span>
|
|
</pre>
|
|
</td>
|
|
</tr>
|
|
|
|
<tr>
|
|
<td class="docs">
|
|
|
|
</td>
|
|
<td class="code leading">
|
|
|
|
<pre class="chroma"> <span class="nx">s</span> <span class="o">:=</span> <span class="kd">struct</span> <span class="p">{</span>
|
|
<span class="nx">Field1</span><span class="p">,</span> <span class="nx">Field2</span> <span class="kd">interface</span><span class="p">{}</span>
|
|
<span class="p">}{}</span>
|
|
</pre>
|
|
</td>
|
|
</tr>
|
|
|
|
<tr>
|
|
<td class="docs">
|
|
|
|
</td>
|
|
<td class="code leading">
|
|
|
|
<pre class="chroma"> <span class="nx">s</span><span class="p">.</span><span class="nx">Field1</span> <span class="p">=</span> <span class="s">""</span>
|
|
<span class="nx">s</span><span class="p">.</span><span class="nx">Field2</span> <span class="p">=</span> <span class="p">[]</span><span class="kt">string</span><span class="p">{}</span>
|
|
<span class="nx">t</span><span class="p">.</span><span class="nf">Execute</span><span class="p">(</span><span class="nx">os</span><span class="p">.</span><span class="nx">Stdout</span><span class="p">,</span> <span class="nx">s</span><span class="p">)</span>
|
|
</pre>
|
|
</td>
|
|
</tr>
|
|
|
|
<tr>
|
|
<td class="docs">
|
|
|
|
</td>
|
|
<td class="code leading">
|
|
|
|
<pre class="chroma"> <span class="nx">s</span><span class="p">.</span><span class="nx">Field1</span> <span class="p">=</span> <span class="kc">nil</span>
|
|
<span class="nx">s</span><span class="p">.</span><span class="nx">Field2</span> <span class="p">=</span> <span class="s">"Some text"</span>
|
|
<span class="nx">t</span><span class="p">.</span><span class="nf">Execute</span><span class="p">(</span><span class="nx">os</span><span class="p">.</span><span class="nx">Stdout</span><span class="p">,</span> <span class="nx">s</span><span class="p">)</span>
|
|
</pre>
|
|
</td>
|
|
</tr>
|
|
|
|
<tr>
|
|
<td class="docs">
|
|
<p>Using a range action you can loop through a slice.
|
|
Each time the range block is getting executed dot will be set
|
|
to current item of slice.
|
|
You can use $ in blocks to access outside data.</p>
|
|
|
|
</td>
|
|
<td class="code leading">
|
|
|
|
<pre class="chroma">
|
|
<span class="nx">t</span><span class="p">,</span> <span class="nx">_</span> <span class="p">=</span> <span class="nx">t</span><span class="p">.</span><span class="nf">Parse</span><span class="p">(</span><span class="s">`Range: </span><span class="cp">{{</span><span class="w"> </span><span class="k">range</span><span class="w"> </span><span class="na">.</span><span class="w"> </span><span class="cp">}}</span><span class="s">
|
|
</span><span class="s"> </span><span class="cp">{{</span><span class="na">.</span><span class="cp">}}</span><span class="s">
|
|
</span><span class="s"> </span><span class="cp">{{</span><span class="w"> </span><span class="k">end</span><span class="w"> </span><span class="cp">}}</span><span class="s">`</span><span class="p">)</span>
|
|
<span class="nx">t</span><span class="p">.</span><span class="nf">Execute</span><span class="p">(</span><span class="nx">os</span><span class="p">.</span><span class="nx">Stdout</span><span class="p">,</span> <span class="p">[]</span><span class="kt">string</span><span class="p">{</span>
|
|
<span class="s">"Go"</span><span class="p">,</span>
|
|
<span class="s">"Rust"</span><span class="p">,</span>
|
|
<span class="s">"C++"</span><span class="p">,</span>
|
|
<span class="s">"C#"</span><span class="p">,</span>
|
|
<span class="p">})</span>
|
|
</pre>
|
|
</td>
|
|
</tr>
|
|
|
|
<tr>
|
|
<td class="docs">
|
|
<p>You can assign and reassign a value to a variable in templates.</p>
|
|
|
|
</td>
|
|
<td class="code">
|
|
|
|
<pre class="chroma">
|
|
<span class="nx">t</span><span class="p">,</span> <span class="nx">_</span> <span class="p">=</span> <span class="nx">t</span><span class="p">.</span><span class="nf">Parse</span><span class="p">(</span><span class="s">`Variables: </span><span class="cp">{{</span><span class="w"> </span><span class="nx">$language</span><span class="w"> </span><span class="o">:=</span><span class="w"> </span><span class="s">"go"</span><span class="w"> </span><span class="cp">}}</span><span class="s">
|
|
</span><span class="s"> </span><span class="cp">{{</span><span class="w"> </span><span class="nx">$language</span><span class="w"> </span><span class="cp">}}</span><span class="s">
|
|
</span><span class="s"> </span><span class="cp">{{</span><span class="w"> </span><span class="nx">$language</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="s">"C"</span><span class="w"> </span><span class="cp">}}</span><span class="s">
|
|
</span><span class="s"> </span><span class="cp">{{</span><span class="w"> </span><span class="nx">$language</span><span class="w"> </span><span class="cp">}}</span><span class="s">`</span><span class="p">)</span>
|
|
<span class="nx">t</span><span class="p">.</span><span class="nf">Execute</span><span class="p">(</span><span class="nx">os</span><span class="p">.</span><span class="nx">Stdout</span><span class="p">,</span> <span class="kc">nil</span><span class="p">)</span>
|
|
<span class="p">}</span>
|
|
</pre>
|
|
</td>
|
|
</tr>
|
|
|
|
</table>
|
|
|
|
<table>
|
|
|
|
<tr>
|
|
<td class="docs">
|
|
|
|
</td>
|
|
<td class="code leading">
|
|
|
|
<pre class="chroma"><span class="gp">$</span> go run templates.go
|
|
<span class="go">Value is my-template
|
|
</span><span class="go">Value is some text
|
|
</span><span class="go">Value is true
|
|
</span><span class="go">Value is 5
|
|
</span><span class="go">Value is [Go Rust C++ C#]
|
|
</span><span class="go">Value is {Arash}
|
|
</span><span class="go">Firstname: Arash, Lastname: Sameni
|
|
</span><span class="go">Firstname: Robert, Lastname: Griesemer</span></pre>
|
|
</td>
|
|
</tr>
|
|
|
|
<tr>
|
|
<td class="docs">
|
|
|
|
</td>
|
|
<td class="code leading">
|
|
|
|
<pre class="chroma"><span class="go"> Else block</span></pre>
|
|
</td>
|
|
</tr>
|
|
|
|
<tr>
|
|
<td class="docs">
|
|
|
|
</td>
|
|
<td class="code leading">
|
|
|
|
<pre class="chroma"><span class="go"> Else if block => Some text
|
|
</span><span class="go">Range:
|
|
</span><span class="go"> Go</span></pre>
|
|
</td>
|
|
</tr>
|
|
|
|
<tr>
|
|
<td class="docs">
|
|
|
|
</td>
|
|
<td class="code leading">
|
|
|
|
<pre class="chroma"><span class="go"> Rust</span></pre>
|
|
</td>
|
|
</tr>
|
|
|
|
<tr>
|
|
<td class="docs">
|
|
|
|
</td>
|
|
<td class="code leading">
|
|
|
|
<pre class="chroma"><span class="go"> C++</span></pre>
|
|
</td>
|
|
</tr>
|
|
|
|
<tr>
|
|
<td class="docs">
|
|
|
|
</td>
|
|
<td class="code">
|
|
|
|
<pre class="chroma"><span class="go"> C#
|
|
</span><span class="go">Variables:
|
|
</span><span class="go">go
|
|
</span><span class="go">C</span></pre>
|
|
</td>
|
|
</tr>
|
|
|
|
</table>
|
|
|
|
|
|
<p class="next">
|
|
Next example: <a href="json">JSON</a>.
|
|
</p>
|
|
|
|
|
|
<p class="footer">
|
|
by <a href="https://markmcgranaghan.com">Mark McGranaghan</a> and <a href="https://eli.thegreenplace.net">Eli Bendersky</a> | <a href="https://github.com/mmcgrana/gobyexample">source</a> | <a href="https://github.com/mmcgrana/gobyexample#license">license</a>
|
|
</p>
|
|
|
|
</div>
|
|
<script>
|
|
var codeLines = [];
|
|
codeLines.push('');codeLines.push('package main\u000A');codeLines.push('import (\u000A \"os\"\u000A \"text/template\"\u000A)\u000A');codeLines.push('func main() {\u000A');codeLines.push(' t :\u003D template.New(\"my-template\")\u000A');codeLines.push(' t, _ \u003D t.Parse(\"Value is {{.}}\\n\")\u000A');codeLines.push(' t \u003D template.Must(t.Parse(\"Value is {{.}}\\n\"))\u000A');codeLines.push(' t.Execute(os.Stdout, t.Name())\u000A t.Execute(os.Stdout, \"some text\")\u000A t.Execute(os.Stdout, true)\u000A t.Execute(os.Stdout, 5)\u000A t.Execute(os.Stdout, []string{\u000A \"Go\",\u000A \"Rust\",\u000A \"C++\",\u000A \"C#\",\u000A })\u000A t.Execute(os.Stdout, struct{ name string }{\u000A name: \"Arash\",\u000A })\u000A');codeLines.push(' t, _ \u003D t.Parse(\"Firstname: {{.Firstname}}\" +\u000A \", Lastname: {{.Lastname}}\\n\")\u000A');codeLines.push(' t.Execute(os.Stdout, struct {\u000A Firstname, Lastname string\u000A }{\u000A Firstname: \"Arash\",\u000A Lastname: \"Sameni\",\u000A })\u000A');codeLines.push(' t.Execute(os.Stdout, map[string]string{\u000A \"Firstname\": \"Robert\",\u000A \"Lastname\": \"Griesemer\",\u000A })\u000A');codeLines.push(' t, _ \u003D t.Parse(`{{if .Field1}}\u000A If block \u003D\u003E {{.Field1}}\u000A {{ else if .Field2}}\u000A Else if block \u003D\u003E {{.Field2}}\u000A {{ else }}\u000A Else block\u000A {{ end }}`)\u000A');codeLines.push(' s :\u003D struct {\u000A Field1, Field2 interface{}\u000A }{}\u000A');codeLines.push(' s.Field1 \u003D \"\"\u000A s.Field2 \u003D []string{}\u000A t.Execute(os.Stdout, s)\u000A');codeLines.push(' s.Field1 \u003D nil\u000A s.Field2 \u003D \"Some text\"\u000A t.Execute(os.Stdout, s)\u000A');codeLines.push(' t, _ \u003D t.Parse(`Range: {{ range . }}\u000A {{.}}\u000A {{ end }}`)\u000A t.Execute(os.Stdout, []string{\u000A \"Go\",\u000A \"Rust\",\u000A \"C++\",\u000A \"C#\",\u000A })\u000A');codeLines.push(' t, _ \u003D t.Parse(`Variables: {{ $language :\u003D \"go\" }}\u000A {{ $language }}\u000A {{ $language \u003D \"C\" }}\u000A {{ $language }}`)\u000A t.Execute(os.Stdout, nil)\u000A}\u000A');codeLines.push('');codeLines.push('');codeLines.push('');codeLines.push('');codeLines.push('');codeLines.push('');
|
|
</script>
|
|
<script src="site.js" async></script>
|
|
</body>
|
|
</html>
|