radarphp.github.io/middleware.html at master · radarphp/radarphp.github.io · GitHub

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
<html>
<head>
    <title>Middleware</title>
    <link rel="stylesheet" href="/css/style.css">
    <link rel="stylesheet" href="https://maxcdn.bootstrapcdn.com/bootstrap/3.3.5/css/bootstrap.min.css">
</head>
<body>

<header>
    <div class="container">
        <div class="row">
            <div class="prev col-md-3">
                                <label for="">Prev</label>
                <a href="/routing.html">Routing</a>            </div>
            <div class="current col-md-6">
                <h3 class="title">
                    4. Middleware                </h3>
                <small class="parent">Radar for PHP</small>
            </div>
            <div class="next col-md-3">
                                <label for="">Next</label>
                <a href="/environment.html">Environment Variables</a>            </div>
            <div class="clearfix"></div>
        </div>
    </div>
</header>

<section id="content">
    <div class="container">
        <div class="row">
            <div class="col-md-12">


<h1 id="4">4. Middleware</h1>
<p>Radar uses the <a href="http://relayphp.com">Relay</a> system for dispatching middleware.
You can read more about middleware there.</p>
<p>To add Relay-compatible middleware entries to the queue, call the
<code>$adr-&gt;middle()</code> method in <code>web/index.php</code>. Pass a class name as the only
parameter to the method. The underlying dependency injection container will
create an instance of that class so that Relay can call its <code>__invoke()</code> method.</p>
<pre><code class="language-php">$adr-&gt;middle('My\Middleware\ClassName');
</code></pre>
<p>Alternatively, pass:</p>
<ul>
<li>
<p>An array of the form <code>['ClassName', 'method']</code>. In this
case, the underlying dependency injection container will create an instance of
that class and call the specified method. The method should be Relay-compatible.</p>
</li>
<li>
<p>A new callable object with a Relay-compatible <code>__invoke()</code> method.</p>
</li>
<li>
<p>An anonymous function with a Relay-compatible signature.</p>
</li>
</ul>
<h2 id="4-1">4.1. Exception Handling</h2>
<p>If middleware in the queue fails to catch an exception, the default
<em>Relay\Middleware\ExceptionHandler</em> will catch it automatically. The
<em>ExceptionHandler</em> will:</p>
<ul>
<li>write the <em>Exception</em> message to a new <em>Response</em> object,</li>
<li>set a <code>500</code> HTTP status code on that new <em>Response</em>,</li>
<li>return the new <em>Response</em> to the previous middleware handler.</li>
</ul>
<p>The <em>ExceptionHandler</em> should be placed after the <em>ResponseSender</em> middleware in
the queue, so that the <em>ResponseSender</em> can then send the exceptional response.</p>
<h2 id="4-2">4.2. Middleware And Domain Activity</h2>
<p>You are going to be very tempted to place domain-related activity in your
middleware, things like "checking to see if a user is authenticated" and so on.
Resist this temptation. Middleware should only be about inspecting and modifying
the request and response, <em>not</em> about handling domain elements. Middleware is
not part of your core application; it is part of the HTTP user interface to that
application.</p>
<p>One shorthand way of determining if you are doing domain work is this: if you
have to touch a storage system of any sort, it's probably domain related. This
includes things like starting a session, which uses some form of storage system
to re-establish itself.</p>
<p>This may seem onerous, but remember: <strong>Radar is an HTTP-specific user interface
wrapper</strong> around your core application. Anything that relates to authentication,
authorization, database, disk, and so on are more properly part of your domain
work, <em>not</em> the user- interface work related to the input and output related to
that domain. All the data you need to work with the domain should come from the
incoming request, and all the data you need to build a response should emit from
the domain as a <em>Payload</em>.</p>

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

<footer>
    <section id="links">
        <div class="container">
            <div class="row">
                <div class="prev col-md-3">
                                        <label for="">Prev</label>
                    <a href="/routing.html">3. Routing</a>                </div>
                <div class="parent col-md-6">
                                        <label for="">Up</label>
                    <a href="/">Radar for PHP</a>                </div>
                <div class="next col-md-3">
                                        <label for="">Next</label>
                    <a href="/environment.html">5. Environment Variables</a>                </div>
                <div class="clearfix"></div>
            </div>
        </div>
    </section>
    <section id="copyright">
        <div class="container">
            <div class="row">
                <div class="col-md-12">

                    <span>
                        Powered by <a href="">Bookdown.io</a> | Designed by <a href="">yuripertamax</a>
                    </span>

                </div>
            </div>
        </div>
    </section>
</footer>
</body>
</html>