235 lines
9.9 KiB
Plaintext
235 lines
9.9 KiB
Plaintext
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<meta http-eqiv="content-type" content="text/html;charset=utf-8">
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<title>Go by Example: URL Parsing</title>
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<div class="example" id="url-parsing">
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<h2><a href="./">Go by Example</a>: URL Parsing</h2>
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<table>
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<tr>
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<td class="docs">
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<p>URLs provide a <a href="http://adam.heroku.com/past/2010/3/30/urls_are_the_uniform_way_to_locate_resources/">uniform way to locate resources</a>.
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Here’s how to parse URLs in Go.</p>
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</td>
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<td class="code empty leading">
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</td>
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<td class="docs">
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</td>
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<td class="code leading">
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<a href="http://play.golang.org/p/eaMv0skOfY"><img title="Run code" src="play.png" class="run" /></a>
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<div class="highlight"><pre><span class="kn">package</span> <span class="nx">main</span>
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</pre></div>
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</td>
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<tr>
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<td class="docs">
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</td>
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<td class="code leading">
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<div class="highlight"><pre><span class="kn">import</span> <span class="s">"fmt"</span>
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<span class="kn">import</span> <span class="s">"net/url"</span>
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<span class="kn">import</span> <span class="s">"strings"</span>
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</pre></div>
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</td>
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</tr>
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<td class="docs">
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<td class="code leading">
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<div class="highlight"><pre><span class="kd">func</span> <span class="nx">main</span><span class="p">()</span> <span class="p">{</span>
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</pre></div>
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</td>
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</tr>
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<tr>
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<td class="docs">
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<p>We’ll parse this example URL, which includes a
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scheme, authentication info, host, port, path,
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query params, and query fragment.</p>
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</td>
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<td class="code leading">
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<div class="highlight"><pre> <span class="nx">s</span> <span class="o">:=</span> <span class="s">"postgres://user:pass@host.com:5432/path?k=v#f"</span>
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</pre></div>
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</td>
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</tr>
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<tr>
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<td class="docs">
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<p>Parse the URL and ensure there are no errors.</p>
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</td>
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<td class="code leading">
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<div class="highlight"><pre> <span class="nx">u</span><span class="p">,</span> <span class="nx">err</span> <span class="o">:=</span> <span class="nx">url</span><span class="p">.</span><span class="nx">Parse</span><span class="p">(</span><span class="nx">s</span><span class="p">)</span>
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<span class="k">if</span> <span class="nx">err</span> <span class="o">!=</span> <span class="kc">nil</span> <span class="p">{</span>
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<span class="nb">panic</span><span class="p">(</span><span class="nx">err</span><span class="p">)</span>
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<span class="p">}</span>
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</pre></div>
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</td>
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</tr>
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<tr>
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<td class="docs">
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<p>Accessing the scheme is straightforward.</p>
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</td>
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<td class="code leading">
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<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">u</span><span class="p">.</span><span class="nx">Scheme</span><span class="p">)</span>
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</pre></div>
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</td>
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</tr>
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<tr>
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<td class="docs">
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<p><code>User</code> contains all authentication info; call
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<code>Username</code> and <code>Password</code> on this for individual
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values.</p>
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</td>
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<td class="code leading">
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<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">u</span><span class="p">.</span><span class="nx">User</span><span class="p">)</span>
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<span class="nx">fmt</span><span class="p">.</span><span class="nx">Println</span><span class="p">(</span><span class="nx">u</span><span class="p">.</span><span class="nx">User</span><span class="p">.</span><span class="nx">Username</span><span class="p">())</span>
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<span class="nx">p</span><span class="p">,</span> <span class="nx">_</span> <span class="o">:=</span> <span class="nx">u</span><span class="p">.</span><span class="nx">User</span><span class="p">.</span><span class="nx">Password</span><span class="p">()</span>
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<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>
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</pre></div>
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</td>
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</tr>
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<tr>
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<td class="docs">
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<p>The <code>Host</code> contains both the hostname and the port,
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if present. <code>Split</code> the <code>Host</code> manually to extract
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the port.</p>
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</td>
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<td class="code leading">
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<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">u</span><span class="p">.</span><span class="nx">Host</span><span class="p">)</span>
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<span class="nx">h</span> <span class="o">:=</span> <span class="nx">strings</span><span class="p">.</span><span class="nx">Split</span><span class="p">(</span><span class="nx">u</span><span class="p">.</span><span class="nx">Host</span><span class="p">,</span> <span class="s">":"</span><span class="p">)</span>
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<span class="nx">fmt</span><span class="p">.</span><span class="nx">Println</span><span class="p">(</span><span class="nx">h</span><span class="p">[</span><span class="mi">0</span><span class="p">])</span>
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<span class="nx">fmt</span><span class="p">.</span><span class="nx">Println</span><span class="p">(</span><span class="nx">h</span><span class="p">[</span><span class="mi">1</span><span class="p">])</span>
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</pre></div>
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</td>
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</tr>
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<tr>
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<td class="docs">
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<p>Here we extract the <code>path</code> and the fragment after
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the <code>#</code>.</p>
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</td>
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<td class="code leading">
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<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">u</span><span class="p">.</span><span class="nx">Path</span><span class="p">)</span>
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<span class="nx">fmt</span><span class="p">.</span><span class="nx">Println</span><span class="p">(</span><span class="nx">u</span><span class="p">.</span><span class="nx">Fragment</span><span class="p">)</span>
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</pre></div>
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</td>
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</tr>
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<tr>
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<td class="docs">
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<p>To get query params in a string of <code>k=v</code> format,
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use <code>RawQuery</code>. You can also parse query params
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into a map. The parsed query param maps are from
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strings to slices of strings, so index into <code>[0]</code>
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if you only want the first value.</p>
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</td>
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<td class="code">
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<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">u</span><span class="p">.</span><span class="nx">RawQuery</span><span class="p">)</span>
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<span class="nx">m</span><span class="p">,</span> <span class="nx">_</span> <span class="o">:=</span> <span class="nx">url</span><span class="p">.</span><span class="nx">ParseQuery</span><span class="p">(</span><span class="nx">u</span><span class="p">.</span><span class="nx">RawQuery</span><span class="p">)</span>
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<span class="nx">fmt</span><span class="p">.</span><span class="nx">Println</span><span class="p">(</span><span class="nx">m</span><span class="p">)</span>
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<span class="nx">fmt</span><span class="p">.</span><span class="nx">Println</span><span class="p">(</span><span class="nx">m</span><span class="p">[</span><span class="s">"k"</span><span class="p">][</span><span class="mi">0</span><span class="p">])</span>
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<span class="p">}</span>
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</pre></div>
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</td>
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</tr>
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</table>
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<table>
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<tr>
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<td class="docs">
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<p>Running our URL parsing program shows all the different
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pieces that we extracted.</p>
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</td>
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<td class="code">
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<div class="highlight"><pre><span class="gp">$</span> go run url-parsing.go
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<span class="go">postgres</span>
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<span class="go">user:pass</span>
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<span class="go">user</span>
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<span class="go">pass</span>
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<span class="go">host.com:5432</span>
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<span class="go">host.com</span>
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<span class="go">5432</span>
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<span class="go">/path</span>
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<span class="go">f</span>
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<span class="go">k=v</span>
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<span class="go">map[k:[v]]</span>
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<span class="go">v</span>
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</pre></div>
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</td>
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</tr>
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</table>
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<p class="next">
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Next example: <a href="sha1-hashes">SHA1 Hashes</a>.
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</p>
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<p class="footer">
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by <a href="https://twitter.com/mmcgrana">@mmcgrana</a> | <a href="mailto:mmcgrana@gmail.com">feedback</a> | <a href="https://github.com/mmcgrana/gobyexample/blob/master/examples/url-parsing">source</a> | <a href="https://github.com/mmcgrana/gobyexample#license">license</a>
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</p>
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</div>
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