1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
|
<!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_req:match_qs(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=1" 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_req:match_qs(3)</span></h1>
<h2 id="_name">Name</h2>
<p>cowboy_req:match_qs - Match the query string against constraints</p>
<h2 id="_description">Description</h2>
<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">match_qs</font></b>(<font color="#009900">Fields</font> <font color="#990000">::</font> <b><font color="#000000">cowboy:fields</font></b>(), <font color="#009900">Req</font> <font color="#990000">::</font> <b><font color="#000000">cowboy_req:req</font></b>())
<font color="#990000">-></font> #{<b><font color="#000080">atom</font></b>() <font color="#990000">=></font> <b><font color="#000000">any</font></b>()}</tt></pre>
</div></div>
<p>Parse the query string and match specific values against constraints.</p>
<p>Cowboy will only return the query string values specified in the fields list, and ignore all others. Fields can be either the key requested; the key along with a list of constraints; or the key, a list of constraints and a default value in case the key is missing.</p>
<p>This function will crash if the key is missing and no default value is provided. This function will also crash if a constraint fails.</p>
<p>The key must be provided as an atom. The key of the returned map will be that atom. The value may be converted through the use of constraints, making this function able to extract, validate and convert values all in one step.</p>
<h2 id="_arguments">Arguments</h2>
<dl><dt>Fields</dt>
<dd><p>Fields to retrieve from the query string.</p>
<p>See <a href="../cowboy">cowboy(3)</a> for a complete description.</p>
</dd>
<dt>Req</dt>
<dd><p>The Req object.</p>
</dd>
</dl>
<h2 id="_return_value">Return value</h2>
<p>Desired values are returned as a map. The key is the atom that was given in the list of fields, and the value is the optionally converted value after applying constraints.</p>
<p>The map contains the same keys that were given in the fields.</p>
<p>An exception is triggered when the match fails.</p>
<h2 id="_changelog">Changelog</h2>
<ul><li><strong>2.0</strong>: Function introduced.
</li>
</ul>
<h2 id="_examples">Examples</h2>
<div class="listingblock"><div class="title">Match fields</div>
<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><i><font color="#9A1900">%% ID and Lang are binaries.</font></i>
#{<font color="#FF6600">id</font> <font color="#990000">:=</font> <font color="#009900">ID</font>, <font color="#FF6600">lang</font> <font color="#990000">:=</font> <font color="#009900">Lang</font>}
<font color="#990000">=</font> <b><font color="#000000">cowboy_req:match_qs</font></b>([<font color="#FF6600">id</font>, <font color="#FF6600">lang</font>], <font color="#009900">Req</font>)<font color="#990000">.</font></tt></pre>
</div></div>
<div class="listingblock"><div class="title">Match fields and apply constraints</div>
<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><i><font color="#9A1900">%% ID is an integer and Lang a non-empty binary.</font></i>
#{<font color="#FF6600">id</font> <font color="#990000">:=</font> <font color="#009900">ID</font>, <font color="#FF6600">lang</font> <font color="#990000">:=</font> <font color="#009900">Lang</font>}
<font color="#990000">=</font> <b><font color="#000000">cowboy_req:match_qs</font></b>([{<font color="#FF6600">id</font>, <font color="#FF6600">int</font>}, {<font color="#FF6600">lang</font>, <font color="#FF6600">nonempty</font>}], <font color="#009900">Req</font>)<font color="#990000">.</font></tt></pre>
</div></div>
<div class="listingblock"><div class="title">Match fields with default values</div>
<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>#{<font color="#FF6600">lang</font> <font color="#990000">:=</font> <font color="#009900">Lang</font>}
<font color="#990000">=</font> <b><font color="#000000">cowboy_req:match_qs</font></b>([{<font color="#FF6600">lang</font>, [], <font color="#990000"><<</font><font color="#FF0000">"en-US"</font><font color="#990000">>></font>}], <font color="#009900">Req</font>)<font color="#990000">.</font></tt></pre>
</div></div>
<h2 id="_see_also">See also</h2>
<p><a href="../cowboy_req">cowboy_req(3)</a>, <a href="../cowboy_req.qs">cowboy_req:qs(3)</a>, <a href="../cowboy_req.parse_qs">cowboy_req:parse_qs(3)</a></p>
</div>
<div class="span3 sidecol">
<h3>
Cowboy
2.3
Function Reference
</h3>
<ul>
<li><a href="/docs/en/cowboy/2.3/guide">User Guide</a></li>
<li><a href="/docs/en/cowboy/2.3/manual">Function Reference</a></li>
</ul>
<h4 id="docs-nav">Navigation</h4>
<h4>Version select</h4>
<ul>
<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>
<li><a href="/docs/en/cowboy/2.1/manual">2.1</a></li>
<li><a href="/docs/en/cowboy/2.0/manual">2.0</a></li>
<li><a href="/docs/en/cowboy/1.0/manual">1.0</a></li>
</ul>
</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 © Loïc Hoguin 2012-2018</p>
</div>
</div>
</div>
</footer>
<script src="/js/custom.js"></script>
</body>
</html>
|
