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gobyexample/public/xml
Hana 9e216da9ef go.mod: add go.mod and move pygments to third_party 
After go1.16, go will use module mode by default,
even when the repository is checked out under GOPATH
or in a one-off directory. Add go.mod, go.sum to keep
this repo buildable without opting out of the module
mode.

> go mod init github.com/mmcgrana/gobyexample
> go mod tidy
> go mod vendor

In module mode, the 'vendor' directory is special
and its contents will be actively maintained by the
go command. pygments aren't the dependency the go will
know about, so it will delete the contents from vendor
directory. Move it to `third_party` directory now.

And, vendor the blackfriday package.

Note: the tutorial contents are not affected by the
change in go1.16 because all the examples in this
tutorial ask users to run the go command with the
explicit list of files to be compiled (e.g.
`go run hello-world.go` or `go build command-line-arguments.go`).
When the source list is provided, the go command does
not have to compute the build list and whether it's
running in GOPATH mode or module mode becomes irrelevant.
2021-02-15 16:45:26 -05:00

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<!DOCTYPE html>
<html>
<head>
<meta charset="utf-8">
<title>Go by Example: XML</title>
<link rel=stylesheet href="site.css">
</head>
<script>
onkeydown = (e) => {
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<body>
<div class="example" id="xml">
<h2><a href="./">Go by Example</a>: XML</h2>
<table>
<tr>
<td class="docs">
<p>Go offers built-in support for XML and XML-like
formats with the <code>encoding.xml</code> package.</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/RsNLhMBazeX"><img title="Run code" src="play.png" class="run" /></a><img title="Copy code" src="clipboard.png" class="copy" />
<div class="highlight"><pre><span class="kn">package</span> <span class="nx">main</span>
</pre></div>
</td>
</tr>
<tr>
<td class="docs">
</td>
<td class="code leading">
<div class="highlight"><pre><span class="kn">import</span> <span class="p">(</span>
<span class="s">&quot;encoding/xml&quot;</span>
<span class="s">&quot;fmt&quot;</span>
<span class="p">)</span>
</pre></div>
</td>
</tr>
<tr>
<td class="docs">
<p>Plant will be mapped to XML. Similarly to the
JSON examples, field tags contain directives for the
encoder and decoder. Here we use some special features
of the XML package: the <code>XMLName</code> field name dictates
the name of the XML element representing this struct;
<code>id,attr</code> means that the <code>Id</code> field is an XML
<em>attribute</em> rather than a nested element.</p>
</td>
<td class="code leading">
<div class="highlight"><pre><span class="kd">type</span> <span class="nx">Plant</span> <span class="kd">struct</span> <span class="p">{</span>
<span class="nx">XMLName</span> <span class="nx">xml</span><span class="p">.</span><span class="nx">Name</span> <span class="s">`xml:&quot;plant&quot;`</span>
<span class="nx">Id</span> <span class="kt">int</span> <span class="s">`xml:&quot;id,attr&quot;`</span>
<span class="nx">Name</span> <span class="kt">string</span> <span class="s">`xml:&quot;name&quot;`</span>
<span class="nx">Origin</span> <span class="p">[]</span><span class="kt">string</span> <span class="s">`xml:&quot;origin&quot;`</span>
<span class="p">}</span>
</pre></div>
</td>
</tr>
<tr>
<td class="docs">
</td>
<td class="code leading">
<div class="highlight"><pre><span class="kd">func</span> <span class="p">(</span><span class="nx">p</span> <span class="nx">Plant</span><span class="p">)</span> <span class="nx">String</span><span class="p">()</span> <span class="kt">string</span> <span class="p">{</span>
<span class="k">return</span> <span class="nx">fmt</span><span class="p">.</span><span class="nx">Sprintf</span><span class="p">(</span><span class="s">&quot;Plant id=%v, name=%v, origin=%v&quot;</span><span class="p">,</span>
<span class="nx">p</span><span class="p">.</span><span class="nx">Id</span><span class="p">,</span> <span class="nx">p</span><span class="p">.</span><span class="nx">Name</span><span class="p">,</span> <span class="nx">p</span><span class="p">.</span><span class="nx">Origin</span><span class="p">)</span>
<span class="p">}</span>
</pre></div>
</td>
</tr>
<tr>
<td class="docs">
</td>
<td class="code leading">
<div class="highlight"><pre><span class="kd">func</span> <span class="nx">main</span><span class="p">()</span> <span class="p">{</span>
<span class="nx">coffee</span> <span class="o">:=</span> <span class="o">&amp;</span><span class="nx">Plant</span><span class="p">{</span><span class="nx">Id</span><span class="p">:</span> <span class="mi">27</span><span class="p">,</span> <span class="nx">Name</span><span class="p">:</span> <span class="s">&quot;Coffee&quot;</span><span class="p">}</span>
<span class="nx">coffee</span><span class="p">.</span><span class="nx">Origin</span> <span class="p">=</span> <span class="p">[]</span><span class="kt">string</span><span class="p">{</span><span class="s">&quot;Ethiopia&quot;</span><span class="p">,</span> <span class="s">&quot;Brazil&quot;</span><span class="p">}</span>
</pre></div>
</td>
</tr>
<tr>
<td class="docs">
<p>Emit XML representing our plant; using
<code>MarshalIndent</code> to produce a more
human-readable output.</p>
</td>
<td class="code leading">
<div class="highlight"><pre> <span class="nx">out</span><span class="p">,</span> <span class="nx">_</span> <span class="o">:=</span> <span class="nx">xml</span><span class="p">.</span><span class="nx">MarshalIndent</span><span class="p">(</span><span class="nx">coffee</span><span class="p">,</span> <span class="s">&quot; &quot;</span><span class="p">,</span> <span class="s">&quot; &quot;</span><span class="p">)</span>
<span class="nx">fmt</span><span class="p">.</span><span class="nx">Println</span><span class="p">(</span><span class="nb">string</span><span class="p">(</span><span class="nx">out</span><span class="p">))</span>
</pre></div>
</td>
</tr>
<tr>
<td class="docs">
<p>To add a generic XML header to the output, append
it explicitly.</p>
</td>
<td class="code leading">
<div class="highlight"><pre> <span class="nx">fmt</span><span class="p">.</span><span class="nx">Println</span><span class="p">(</span><span class="nx">xml</span><span class="p">.</span><span class="nx">Header</span> <span class="o">+</span> <span class="nb">string</span><span class="p">(</span><span class="nx">out</span><span class="p">))</span>
</pre></div>
</td>
</tr>
<tr>
<td class="docs">
<p>Use <code>Unmarhshal</code> to parse a stream of bytes with XML
into a data structure. If the XML is malformed or
cannot be mapped onto Plant, a descriptive error
will be returned.</p>
</td>
<td class="code leading">
<div class="highlight"><pre> <span class="kd">var</span> <span class="nx">p</span> <span class="nx">Plant</span>
<span class="k">if</span> <span class="nx">err</span> <span class="o">:=</span> <span class="nx">xml</span><span class="p">.</span><span class="nx">Unmarshal</span><span class="p">(</span><span class="nx">out</span><span class="p">,</span> <span class="o">&amp;</span><span class="nx">p</span><span class="p">);</span> <span class="nx">err</span> <span class="o">!=</span> <span class="kc">nil</span> <span class="p">{</span>
<span class="nb">panic</span><span class="p">(</span><span class="nx">err</span><span class="p">)</span>
<span class="p">}</span>
<span class="nx">fmt</span><span class="p">.</span><span class="nx">Println</span><span class="p">(</span><span class="nx">p</span><span class="p">)</span>
</pre></div>
</td>
</tr>
<tr>
<td class="docs">
</td>
<td class="code leading">
<div class="highlight"><pre> <span class="nx">tomato</span> <span class="o">:=</span> <span class="o">&amp;</span><span class="nx">Plant</span><span class="p">{</span><span class="nx">Id</span><span class="p">:</span> <span class="mi">81</span><span class="p">,</span> <span class="nx">Name</span><span class="p">:</span> <span class="s">&quot;Tomato&quot;</span><span class="p">}</span>
<span class="nx">tomato</span><span class="p">.</span><span class="nx">Origin</span> <span class="p">=</span> <span class="p">[]</span><span class="kt">string</span><span class="p">{</span><span class="s">&quot;Mexico&quot;</span><span class="p">,</span> <span class="s">&quot;California&quot;</span><span class="p">}</span>
</pre></div>
</td>
</tr>
<tr>
<td class="docs">
<p>The <code>parent&gt;child&gt;plant</code> field tag tells the encoder
to nest all <code>plant</code>s under <code>&lt;parent&gt;&lt;child&gt;...</code></p>
</td>
<td class="code leading">
<div class="highlight"><pre> <span class="kd">type</span> <span class="nx">Nesting</span> <span class="kd">struct</span> <span class="p">{</span>
<span class="nx">XMLName</span> <span class="nx">xml</span><span class="p">.</span><span class="nx">Name</span> <span class="s">`xml:&quot;nesting&quot;`</span>
<span class="nx">Plants</span> <span class="p">[]</span><span class="o">*</span><span class="nx">Plant</span> <span class="s">`xml:&quot;parent&gt;child&gt;plant&quot;`</span>
<span class="p">}</span>
</pre></div>
</td>
</tr>
<tr>
<td class="docs">
</td>
<td class="code leading">
<div class="highlight"><pre> <span class="nx">nesting</span> <span class="o">:=</span> <span class="o">&amp;</span><span class="nx">Nesting</span><span class="p">{}</span>
<span class="nx">nesting</span><span class="p">.</span><span class="nx">Plants</span> <span class="p">=</span> <span class="p">[]</span><span class="o">*</span><span class="nx">Plant</span><span class="p">{</span><span class="nx">coffee</span><span class="p">,</span> <span class="nx">tomato</span><span class="p">}</span>
</pre></div>
</td>
</tr>
<tr>
<td class="docs">
</td>
<td class="code">
<div class="highlight"><pre> <span class="nx">out</span><span class="p">,</span> <span class="nx">_</span> <span class="p">=</span> <span class="nx">xml</span><span class="p">.</span><span class="nx">MarshalIndent</span><span class="p">(</span><span class="nx">nesting</span><span class="p">,</span> <span class="s">&quot; &quot;</span><span class="p">,</span> <span class="s">&quot; &quot;</span><span class="p">)</span>
<span class="nx">fmt</span><span class="p">.</span><span class="nx">Println</span><span class="p">(</span><span class="nb">string</span><span class="p">(</span><span class="nx">out</span><span class="p">))</span>
<span class="p">}</span>
</pre></div>
</td>
</tr>
</table>
<table>
<tr>
<td class="docs">
</td>
<td class="code">
<div class="highlight"><pre><span class="gp">$</span> go run xml.go
<span class="go"> &lt;plant id=&quot;27&quot;&gt;</span>
<span class="go"> &lt;name&gt;Coffee&lt;/name&gt;</span>
<span class="go"> &lt;origin&gt;Ethiopia&lt;/origin&gt;</span>
<span class="go"> &lt;origin&gt;Brazil&lt;/origin&gt;</span>
<span class="go"> &lt;/plant&gt;</span>
<span class="go">&lt;?xml version=&quot;1.0&quot; encoding=&quot;UTF-8&quot;?&gt;</span>
<span class="go"> &lt;plant id=&quot;27&quot;&gt;</span>
<span class="go"> &lt;name&gt;Coffee&lt;/name&gt;</span>
<span class="go"> &lt;origin&gt;Ethiopia&lt;/origin&gt;</span>
<span class="go"> &lt;origin&gt;Brazil&lt;/origin&gt;</span>
<span class="go"> &lt;/plant&gt;</span>
<span class="go">Plant id=27, name=Coffee, origin=[Ethiopia Brazil]</span>
<span class="go"> &lt;nesting&gt;</span>
<span class="go"> &lt;parent&gt;</span>
<span class="go"> &lt;child&gt;</span>
<span class="go"> &lt;plant id=&quot;27&quot;&gt;</span>
<span class="go"> &lt;name&gt;Coffee&lt;/name&gt;</span>
<span class="go"> &lt;origin&gt;Ethiopia&lt;/origin&gt;</span>
<span class="go"> &lt;origin&gt;Brazil&lt;/origin&gt;</span>
<span class="go"> &lt;/plant&gt;</span>
<span class="go"> &lt;plant id=&quot;81&quot;&gt;</span>
<span class="go"> &lt;name&gt;Tomato&lt;/name&gt;</span>
<span class="go"> &lt;origin&gt;Mexico&lt;/origin&gt;</span>
<span class="go"> &lt;origin&gt;California&lt;/origin&gt;</span>
<span class="go"> &lt;/plant&gt;</span>
<span class="go"> &lt;/child&gt;</span>
<span class="go"> &lt;/parent&gt;</span>
<span class="go"> &lt;/nesting&gt;</span>
</pre></div>
</td>
</tr>
</table>
<p class="next">
Next example: <a href="time">Time</a>.
</p>
<p class="footer">
by <a href="https://markmcgranaghan.com">Mark McGranaghan</a> | <a href="https://github.com/mmcgrana/gobyexample/blob/master/examples/xml">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 \"encoding/xml\"\u000A \"fmt\"\u000A)\u000A');codeLines.push('type Plant struct {\u000A XMLName xml.Name `xml:\"plant\"`\u000A Id int `xml:\"id,attr\"`\u000A Name string `xml:\"name\"`\u000A Origin []string `xml:\"origin\"`\u000A}\u000A');codeLines.push('func (p Plant) String() string {\u000A return fmt.Sprintf(\"Plant id\u003D%v, name\u003D%v, origin\u003D%v\",\u000A p.Id, p.Name, p.Origin)\u000A}\u000A');codeLines.push('func main() {\u000A coffee :\u003D \u0026Plant{Id: 27, Name: \"Coffee\"}\u000A coffee.Origin \u003D []string{\"Ethiopia\", \"Brazil\"}\u000A');codeLines.push(' out, _ :\u003D xml.MarshalIndent(coffee, \" \", \" \")\u000A fmt.Println(string(out))\u000A');codeLines.push(' fmt.Println(xml.Header + string(out))\u000A');codeLines.push(' var p Plant\u000A if err :\u003D xml.Unmarshal(out, \u0026p); err !\u003D nil {\u000A panic(err)\u000A }\u000A fmt.Println(p)\u000A');codeLines.push(' tomato :\u003D \u0026Plant{Id: 81, Name: \"Tomato\"}\u000A tomato.Origin \u003D []string{\"Mexico\", \"California\"}\u000A');codeLines.push(' type Nesting struct {\u000A XMLName xml.Name `xml:\"nesting\"`\u000A Plants []*Plant `xml:\"parent\u003Echild\u003Eplant\"`\u000A }\u000A');codeLines.push(' nesting :\u003D \u0026Nesting{}\u000A nesting.Plants \u003D []*Plant{coffee, tomato}\u000A');codeLines.push(' out, _ \u003D xml.MarshalIndent(nesting, \" \", \" \")\u000A fmt.Println(string(out))\u000A}\u000A');codeLines.push('');
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<script src="site.js" async></script>
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