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<title>class Rack::ETag - rack-2.2.24 Documentation</title>

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  <h3>Parent</h3>

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  <h3>Methods</h3>

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    <li ><a href="#method-c-new">::new</a>
    
    <li ><a href="#method-i-call">#call</a>
    
    <li ><a href="#method-i-digest_body">#digest_body</a>
    
    <li ><a href="#method-i-etag_body-3F">#etag_body?</a>
    
    <li ><a href="#method-i-etag_status-3F">#etag_status?</a>
    
    <li ><a href="#method-i-skip_caching-3F">#skip_caching?</a>
    
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<main role="main" aria-labelledby="class-Rack::ETag">
  <h1 id="class-Rack::ETag" class="class">
    class Rack::ETag
  </h1>

<section class="description">
    
<p>Automatically sets the <a href="ETag.html"><code>ETag</code></a> header on all String bodies.</p>

<p>The <a href="ETag.html"><code>ETag</code></a> header is skipped if <a href="ETag.html"><code>ETag</code></a> or Last-Modified headers are sent or if a sendfile body (body.responds_to :to_path) is given (since such cases should be handled by apache/nginx).</p>

<p>On initialization, you can pass two parameters: a Cache-Control directive used when Etag is absent and a directive when it is present. The first defaults to nil, while the second defaults to “max-age=0, private, must-revalidate”</p>

</section>

<section class="constants-list">
      <header>
        <h3>Constants</h3>
      </header>
      <dl>
      
        <dt id="DEFAULT_CACHE_CONTROL">DEFAULT_CACHE_CONTROL
        
        <dd>
        
      
        <dt id="ETAG_STRING">ETAG_STRING
        
        <dd>
        
      
      </dl>
    </section>

<section id="public-class-5Buntitled-5D-method-details" class="method-section">
       <header>
         <h3>Public Class Methods</h3>
       </header>

<div id="method-c-new" class="method-detail ">
        
        <div class="method-heading">
          <span class="method-name">new</span><span
            class="method-args">(app, no_cache_control = nil, cache_control = DEFAULT_CACHE_CONTROL)</span>
          
          <span class="method-click-advice">click to toggle source</span>
          
        </div>

<div class="method-source-code" id="new-source">
            <pre><span class="ruby-comment"># File lib/rack/etag.rb, line 20</span>
<span class="ruby-keyword">def</span> <span class="ruby-identifier ruby-title">initialize</span>(<span class="ruby-identifier">app</span>, <span class="ruby-identifier">no_cache_control</span> = <span class="ruby-keyword">nil</span>, <span class="ruby-identifier">cache_control</span> = <span class="ruby-constant">DEFAULT_CACHE_CONTROL</span>)
  <span class="ruby-ivar">@app</span> = <span class="ruby-identifier">app</span>
  <span class="ruby-ivar">@cache_control</span> = <span class="ruby-identifier">cache_control</span>
  <span class="ruby-ivar">@no_cache_control</span> = <span class="ruby-identifier">no_cache_control</span>
<span class="ruby-keyword">end</span></pre>
          </div>
          
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</section>
  
     <section id="public-instance-5Buntitled-5D-method-details" class="method-section">
       <header>
         <h3>Public Instance Methods</h3>
       </header>

<div id="method-i-call" class="method-detail ">
        
        <div class="method-heading">
          <span class="method-name">call</span><span
            class="method-args">(env)</span>
          
          <span class="method-click-advice">click to toggle source</span>
          
        </div>

<div class="method-source-code" id="call-source">
            <pre><span class="ruby-comment"># File lib/rack/etag.rb, line 26</span>
<span class="ruby-keyword">def</span> <span class="ruby-identifier ruby-title">call</span>(<span class="ruby-identifier">env</span>)
  <span class="ruby-identifier">status</span>, <span class="ruby-identifier">headers</span>, <span class="ruby-identifier">body</span> = <span class="ruby-ivar">@app</span>.<span class="ruby-identifier">call</span>(<span class="ruby-identifier">env</span>)

<span class="ruby-identifier">headers</span> = <span class="ruby-constant">Utils</span><span class="ruby-operator">::</span><span class="ruby-constant">HeaderHash</span>[<span class="ruby-identifier">headers</span>]

<span class="ruby-keyword">if</span> <span class="ruby-identifier">etag_status?</span>(<span class="ruby-identifier">status</span>) <span class="ruby-operator">&amp;&amp;</span> <span class="ruby-identifier">etag_body?</span>(<span class="ruby-identifier">body</span>) <span class="ruby-operator">&amp;&amp;</span> <span class="ruby-operator">!</span><span class="ruby-identifier">skip_caching?</span>(<span class="ruby-identifier">headers</span>)
    <span class="ruby-identifier">original_body</span> = <span class="ruby-identifier">body</span>
    <span class="ruby-identifier">digest</span>, <span class="ruby-identifier">new_body</span> = <span class="ruby-identifier">digest_body</span>(<span class="ruby-identifier">body</span>)
    <span class="ruby-identifier">body</span> = <span class="ruby-constant">Rack</span><span class="ruby-operator">::</span><span class="ruby-constant">BodyProxy</span>.<span class="ruby-identifier">new</span>(<span class="ruby-identifier">new_body</span>) <span class="ruby-keyword">do</span>
      <span class="ruby-identifier">original_body</span>.<span class="ruby-identifier">close</span> <span class="ruby-keyword">if</span> <span class="ruby-identifier">original_body</span>.<span class="ruby-identifier">respond_to?</span>(<span class="ruby-value">:close</span>)
    <span class="ruby-keyword">end</span>
    <span class="ruby-identifier">headers</span>[<span class="ruby-constant">ETAG_STRING</span>] = <span class="ruby-node">%(W/&quot;#{digest}&quot;)</span> <span class="ruby-keyword">if</span> <span class="ruby-identifier">digest</span>
  <span class="ruby-keyword">end</span>

<span class="ruby-keyword">unless</span> <span class="ruby-identifier">headers</span>[<span class="ruby-constant">CACHE_CONTROL</span>]
    <span class="ruby-keyword">if</span> <span class="ruby-identifier">digest</span>
      <span class="ruby-identifier">headers</span>[<span class="ruby-constant">CACHE_CONTROL</span>] = <span class="ruby-ivar">@cache_control</span> <span class="ruby-keyword">if</span> <span class="ruby-ivar">@cache_control</span>
    <span class="ruby-keyword">else</span>
      <span class="ruby-identifier">headers</span>[<span class="ruby-constant">CACHE_CONTROL</span>] = <span class="ruby-ivar">@no_cache_control</span> <span class="ruby-keyword">if</span> <span class="ruby-ivar">@no_cache_control</span>
    <span class="ruby-keyword">end</span>
  <span class="ruby-keyword">end</span>

[<span class="ruby-identifier">status</span>, <span class="ruby-identifier">headers</span>, <span class="ruby-identifier">body</span>]
<span class="ruby-keyword">end</span></pre>
          </div>
          
        </div>

</div>

</section>
  
     <section id="private-instance-5Buntitled-5D-method-details" class="method-section">
       <header>
         <h3>Private Instance Methods</h3>
       </header>

<div id="method-i-digest_body" class="method-detail ">
        
        <div class="method-heading">
          <span class="method-name">digest_body</span><span
            class="method-args">(body)</span>
          
          <span class="method-click-advice">click to toggle source</span>
          
        </div>

<div class="method-source-code" id="digest_body-source">
            <pre><span class="ruby-comment"># File lib/rack/etag.rb, line 65</span>
<span class="ruby-keyword">def</span> <span class="ruby-identifier ruby-title">digest_body</span>(<span class="ruby-identifier">body</span>)
  <span class="ruby-identifier">parts</span> = []
  <span class="ruby-identifier">digest</span> = <span class="ruby-keyword">nil</span>

<span class="ruby-identifier">body</span>.<span class="ruby-identifier">each</span> <span class="ruby-keyword">do</span> <span class="ruby-operator">|</span><span class="ruby-identifier">part</span><span class="ruby-operator">|</span>
    <span class="ruby-identifier">parts</span> <span class="ruby-operator">&lt;&lt;</span> <span class="ruby-identifier">part</span>
    (<span class="ruby-identifier">digest</span> <span class="ruby-operator">||=</span> <span class="ruby-constant">Digest</span><span class="ruby-operator">::</span><span class="ruby-constant">SHA256</span>.<span class="ruby-identifier">new</span>) <span class="ruby-operator">&lt;&lt;</span> <span class="ruby-identifier">part</span> <span class="ruby-keyword">unless</span> <span class="ruby-identifier">part</span>.<span class="ruby-identifier">empty?</span>
  <span class="ruby-keyword">end</span>

[<span class="ruby-identifier">digest</span> <span class="ruby-operator">&amp;&amp;</span> <span class="ruby-identifier">digest</span>.<span class="ruby-identifier">hexdigest</span>.<span class="ruby-identifier">byteslice</span>(<span class="ruby-value">0</span>, <span class="ruby-value">32</span>), <span class="ruby-identifier">parts</span>]
<span class="ruby-keyword">end</span></pre>
          </div>
          
        </div>

</div>

<div id="method-i-etag_body-3F" class="method-detail ">
        
        <div class="method-heading">
          <span class="method-name">etag_body?</span><span
            class="method-args">(body)</span>
          
          <span class="method-click-advice">click to toggle source</span>
          
        </div>

<div class="method-source-code" id="etag_body-3F-source">
            <pre><span class="ruby-comment"># File lib/rack/etag.rb, line 57</span>
<span class="ruby-keyword">def</span> <span class="ruby-identifier ruby-title">etag_body?</span>(<span class="ruby-identifier">body</span>)
  <span class="ruby-operator">!</span><span class="ruby-identifier">body</span>.<span class="ruby-identifier">respond_to?</span>(<span class="ruby-value">:to_path</span>)
<span class="ruby-keyword">end</span></pre>
          </div>
          
        </div>

</div>

<div id="method-i-etag_status-3F" class="method-detail ">
        
        <div class="method-heading">
          <span class="method-name">etag_status?</span><span
            class="method-args">(status)</span>
          
          <span class="method-click-advice">click to toggle source</span>
          
        </div>

<div class="method-source-code" id="etag_status-3F-source">
            <pre><span class="ruby-comment"># File lib/rack/etag.rb, line 53</span>
<span class="ruby-keyword">def</span> <span class="ruby-identifier ruby-title">etag_status?</span>(<span class="ruby-identifier">status</span>)
  <span class="ruby-identifier">status</span> <span class="ruby-operator">==</span> <span class="ruby-value">200</span> <span class="ruby-operator">||</span> <span class="ruby-identifier">status</span> <span class="ruby-operator">==</span> <span class="ruby-value">201</span>
<span class="ruby-keyword">end</span></pre>
          </div>
          
        </div>

</div>

<div id="method-i-skip_caching-3F" class="method-detail ">
        
        <div class="method-heading">
          <span class="method-name">skip_caching?</span><span
            class="method-args">(headers)</span>
          
          <span class="method-click-advice">click to toggle source</span>
          
        </div>

<div class="method-source-code" id="skip_caching-3F-source">
            <pre><span class="ruby-comment"># File lib/rack/etag.rb, line 61</span>
<span class="ruby-keyword">def</span> <span class="ruby-identifier ruby-title">skip_caching?</span>(<span class="ruby-identifier">headers</span>)
  <span class="ruby-identifier">headers</span>.<span class="ruby-identifier">key?</span>(<span class="ruby-constant">ETAG_STRING</span>) <span class="ruby-operator">||</span> <span class="ruby-identifier">headers</span>.<span class="ruby-identifier">key?</span>(<span class="ruby-string">&#39;Last-Modified&#39;</span>)
<span class="ruby-keyword">end</span></pre>
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