summaryrefslogblamecommitdiffstats
path: root/docs/en/cowboy/2.5/manual/cowboy_constraints/index.html
blob: 3717c1b96b3d0d5d5382a81e637c0a44a33c21af (plain) (tree)
1
2
3
4
5
6
7
8
9
10
11
12











                                                                                                                      
                                                   

























































































































                                                                                                                                                                                                                                                         

                                                                     







                                                                     

     















                                                                                                                                                                                                                                     





























                                                                                                                                                                                                                           
<!DOCTYPE html>
<html lang="en">

<head>
    <meta charset="utf-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <meta name="description" content="">
    <meta name="author" content="Loïc Hoguin based on a design from (Soft10) Pol Cámara">

    <title>Nine Nines: cowboy_constraints(3)</title>

    <link href='https://fonts.googleapis.com/css?family=Open+Sans:400,700,400italic' rel='stylesheet' type='text/css'>
    <link href="/css/99s.css?r=5" rel="stylesheet">

    <link rel="shortcut icon" href="/img/ico/favicon.ico">
    <link rel="apple-touch-icon-precomposed" sizes="114x114" href="/img/ico/apple-touch-icon-114.png">
    <link rel="apple-touch-icon-precomposed" sizes="72x72" href="/img/ico/apple-touch-icon-72.png">
    <link rel="apple-touch-icon-precomposed" href="/img/ico/apple-touch-icon-57.png">

    
</head>


<body class="">
  <header id="page-head">
    <div id="topbar" class="container">
        <div class="row">
          <div class="span2">
            <h1 id="logo"><a href="/" title="99s">99s</a></h1>
          </div>
          <div class="span10">
            
            <div id="side-header">
              <nav>
                <ul>
                  <li><a title="Hear my thoughts" href="/articles">Articles</a></li>
  				  <li><a title="Watch my talks" href="/talks">Talks</a></li>
  				  <li class="active"><a title="Read the docs" href="/docs">Documentation</a></li>
  				  <li><a title="Request my services" href="/services">Consulting & Training</a></li>
                </ul>
              </nav> 
              <ul id="social">
                <li>
                  <a href="https://github.com/ninenines" title="Check my Github repositories"><img src="/img/ico_github.png" data-hover="/img/ico_github_alt.png" alt="Github"></a>
                </li>
                    <li>
						<a title="Contact me" href="mailto:[email protected]"><img src="/img/ico_mail.png" data-hover="/img/ico_mail_alt.png"></a>
					</li>
              </ul>
            </div>
          </div>
        </div>
    </div>


</header>

<div id="contents" class="two_col">
<div class="container">
<div class="row">
<div id="docs" class="span9 maincol">

<h1 class="lined-header"><span>cowboy_constraints(3)</span></h1>

<h2 id="_name">Name</h2>
<p>cowboy_constraints - Constraints</p>
<h2 id="_description">Description</h2>
<p>The module <code>cowboy_constraints</code> defines the built-in constraints in Cowboy and provides an interface for manipulating these constraints.</p>
<p>Constraints are functions that define what type of input is allowed. They are used throughout Cowboy, from the router to query strings to cookies.</p>
<h2 id="_exports">Exports</h2>
<p>Built-in constraints:</p>
<ul><li><a href="../cowboy_constraints.int">cowboy_constraints:int(3)</a> - Integer constraint
</li>
<li><a href="../cowboy_constraints.nonempty">cowboy_constraints:nonempty(3)</a> - Non-empty constraint
</li>
</ul>
<h2 id="_types">Types</h2>
<h3 id="_constraint">constraint()</h3>
<div class="listingblock"><div class="content"><!-- Generator: GNU source-highlight 3.1.8
by Lorenzo Bettini
http://www.lorenzobettini.it
http://www.gnu.org/software/src-highlite -->
<pre><tt><b><font color="#000000">constraint</font></b>() <font color="#990000">::</font> <font color="#FF6600">int</font> | <font color="#FF6600">nonempty</font> | <b><font color="#0000FF">fun</font></b>()</tt></pre>
</div></div>
<p>A constraint function.</p>
<p>The atom constraints are built-in, see the corresponding function in the exports list above.</p>
<h3 id="_reason">reason()</h3>
<div class="listingblock"><div class="content"><!-- Generator: GNU source-highlight 3.1.8
by Lorenzo Bettini
http://www.lorenzobettini.it
http://www.gnu.org/software/src-highlite -->
<pre><tt><b><font color="#000000">reason</font></b>() <font color="#990000">::</font> {<b><font color="#000000">constraint</font></b>(), <font color="#009900">Reason</font>, <font color="#009900">Value</font>}

<font color="#009900">Reason</font> <font color="#990000">::</font> <b><font color="#000000">any</font></b>()
<font color="#009900">Value</font>  <font color="#990000">::</font> <b><font color="#000000">any</font></b>()</tt></pre>
</div></div>
<p>Reason for the constraint failure.</p>
<p>It includes the constraint function in question, a machine-readable error reason and the value that made the constraint fail.</p>
<h2 id="_see_also">See also</h2>
<p><a href="..">cowboy(7)</a>, <a href="../cowboy">cowboy(3)</a>, <a href="../cowboy_router">cowboy_router(3)</a>, <a href="../cowboy_req.match_cookies">cowboy_req:match_cookies(3)</a>, <a href="../cowboy_req.match_qs">cowboy_req:match_qs(3)</a></p>






</div>

<div class="span3 sidecol">


<h3>
	Cowboy
	2.5
	Function Reference
	
</h3>

<ul>
	
		<li><a href="/docs/en/cowboy/2.5/guide">User Guide</a></li>
	
	
		<li><a href="/docs/en/cowboy/2.5/manual">Function Reference</a></li>
	
	
</ul>

<h4 id="docs-nav">Navigation</h4>

<h4>Version select</h4>
<ul>
	
	
	
		<li><a href="/docs/en/cowboy/2.6/manual">2.6</a></li>
	
		<li><a href="/docs/en/cowboy/2.5/manual">2.5</a></li>
	
		<li><a href="/docs/en/cowboy/2.4/manual">2.4</a></li>
	
		<li><a href="/docs/en/cowboy/2.3/manual">2.3</a></li>
	
		<li><a href="/docs/en/cowboy/2.2/manual">2.2</a></li>
	
</ul>

<h3 id="_like_my_work__donate">Like my work? Donate!</h3>
<p>Donate to Loïc Hoguin because his work on Cowboy, Ranch, Gun and Erlang.mk is fantastic:</p>
<form action="https://www.paypal.com/cgi-bin/webscr" method="post" style="display:inline">
<input type="hidden" name="cmd" value="_donations">
<input type="hidden" name="business" value="[email protected]">
<input type="hidden" name="lc" value="FR">
<input type="hidden" name="item_name" value="Loic Hoguin">
<input type="hidden" name="item_number" value="99s">
<input type="hidden" name="currency_code" value="EUR">
<input type="hidden" name="bn" value="PP-DonationsBF:btn_donate_LG.gif:NonHosted">
<input type="image" src="https://www.paypalobjects.com/en_US/i/btn/btn_donate_LG.gif" border="0" name="submit" alt="PayPal - The safer, easier way to pay online!">
<img alt="" border="0" src="https://www.paypalobjects.com/fr_FR/i/scr/pixel.gif" width="1" height="1">
</form><p>Recurring payment options are also available via <a href="https://salt.bountysource.com/teams/ninenines">BountySource</a>. These funds are used to cover the recurring expenses like dedicated servers or domain names.</p>



</div>
</div>
</div>
</div>

      <footer>
        <div class="container">
          <div class="row">
            <div class="span6">
              <p id="scroll-top"><a href="#">↑ Scroll to top</a></p>
              <nav>
                <ul>
                  <li><a href="mailto:[email protected]" title="Contact us">Contact us</a></li><li><a href="https://github.com/ninenines/ninenines.github.io" title="Github repository">Contribute to this site</a></li>
                </ul>
              </nav>
            </div>
            <div class="span6 credits">
               <p><img src="/img/footer_logo.png"></p>
               <p>Copyright &copy; Loïc Hoguin 2012-2018</p>
            </div>
          </div>
        </div>
      </footer>

    
    <script src="/js/custom.js"></script>
  </body>
</html>