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<h1 class="lined-header"><span>cowboy_req:read_body(3)</span></h1>
<div class="sect1">
<h2 id="_name">Name</h2>
<div class="sectionbody">
<div class="paragraph"><p>cowboy_req:read_body - Read the request body</p></div>
</div>
</div>
<div class="sect1">
<h2 id="_description">Description</h2>
<div class="sectionbody">
<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><span style="font-weight: bold"><span style="color: #000000">read_body</span></span>(<span style="color: #009900">Req</span> <span style="color: #990000">::</span> <span style="font-weight: bold"><span style="color: #000000">cowboy_req:req</span></span>())
<span style="color: #990000">-></span> <span style="font-weight: bold"><span style="color: #000000">read_body</span></span>(<span style="color: #009900">Req</span>, #{})
<span style="font-weight: bold"><span style="color: #000000">read_body</span></span>(<span style="color: #009900">Req</span> <span style="color: #990000">::</span> <span style="font-weight: bold"><span style="color: #000000">cowboy_req:req</span></span>(), <span style="color: #009900">Opts</span>)
<span style="color: #990000">-></span> {<span style="color: #FF6600">ok</span>, <span style="color: #009900">Data</span> <span style="color: #990000">::</span> <span style="font-weight: bold"><span style="color: #000080">binary</span></span>(), <span style="color: #009900">Req</span>}
| {<span style="color: #FF6600">more</span>, <span style="color: #009900">Data</span> <span style="color: #990000">::</span> <span style="font-weight: bold"><span style="color: #000080">binary</span></span>(), <span style="color: #009900">Req</span>}
<span style="color: #009900">Opts</span> <span style="color: #990000">::</span> <span style="font-weight: bold"><span style="color: #000000">cowboy_req:read_body_opts</span></span>()</tt></pre></div></div>
<div class="paragraph"><p>Read the request body.</p></div>
<div class="paragraph"><p>This function reads a chunk of the request body. A <code>more</code> tuple
is returned when more data remains to be read. Call the function
repeatedly until an <code>ok</code> tuple is returned to read the entire body.</p></div>
<div class="paragraph"><p>An <code>ok</code> tuple with empty data is returned when the request has no body,
or when calling this function again after the body has already
been read. It is therefore safe to call this function directly.
Note that the body can only be read once.</p></div>
<div class="paragraph"><p>This function reads the request body from the connection process.
The connection process is responsible for reading from the socket.
The exact behavior varies depending on the protocol.</p></div>
<div class="paragraph"><p>The options therefore are only related to the communication
between the request process and the connection process.</p></div>
<div class="paragraph"><p>Cowboy will automatically handle protocol details including
the expect header, chunked transfer-encoding and others.</p></div>
<div class="paragraph"><p>Once the body has been read fully, Cowboy sets the content-length
header if it was not previously provided.</p></div>
</div>
</div>
<div class="sect1">
<h2 id="_arguments">Arguments</h2>
<div class="sectionbody">
<div class="dlist"><dl>
<dt class="hdlist1">
Req
</dt>
<dd>
<p>
The Req object.
</p>
</dd>
<dt class="hdlist1">
Opts
</dt>
<dd>
<p>
A map of body reading options.
</p>
<div class="paragraph"><p>The <code>length</code> option can be used to request smaller or bigger
chunks of data to be sent. It is a best effort approach, Cowboy
may send more data than configured on occasions. It defaults
to 8MB.</p></div>
<div class="paragraph"><p>The <code>period</code> indicates how long the connection process will wait
before it provides us with the data it received. It defaults
to 15 seconds.</p></div>
<div class="paragraph"><p>The connection process sends data to the request process when
either the <code>length</code> of data or the <code>period</code> of time is reached.</p></div>
<div class="paragraph"><p>The <code>timeout</code> option is a safeguard in case the connection
process becomes unresponsive. The function will crash if no
message was received in that interval. The timeout should be
larger than the period. It defaults to the period + 1 second.</p></div>
</dd>
</dl></div>
</div>
</div>
<div class="sect1">
<h2 id="_return_value">Return value</h2>
<div class="sectionbody">
<div class="paragraph"><p>A <code>more</code> tuple is returned when there are more data to be read.</p></div>
<div class="paragraph"><p>An <code>ok</code> tuple is returned when there are no more data to be read,
either because this is the last chunk of data, the body has already
been read, or there was no body to begin with.</p></div>
<div class="paragraph"><p>The data is always returned as a binary.</p></div>
<div class="paragraph"><p>The Req object returned in the tuple must be used for that point
onward. It contains a more up to date representation of the request.
For example it may have an added content-length header once the
body has been read.</p></div>
</div>
</div>
<div class="sect1">
<h2 id="_changelog">Changelog</h2>
<div class="sectionbody">
<div class="ulist"><ul>
<li>
<p>
<strong>2.0</strong>: Function introduced. Replaces <code>body/1,2</code>.
</p>
</li>
</ul></div>
</div>
</div>
<div class="sect1">
<h2 id="_examples">Examples</h2>
<div class="sectionbody">
<div class="listingblock">
<div class="title">Read the entire body</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><span style="font-weight: bold"><span style="color: #000000">read_body</span></span>(<span style="color: #009900">Req0</span>, <span style="color: #009900">Acc</span>) <span style="color: #990000">-></span>
<span style="font-weight: bold"><span style="color: #0000FF">case</span></span> <span style="font-weight: bold"><span style="color: #000000">cowboy_req:read_body</span></span>(<span style="color: #009900">Req0</span>) <span style="font-weight: bold"><span style="color: #0000FF">of</span></span>
{<span style="color: #FF6600">ok</span>, <span style="color: #009900">Data</span>, <span style="color: #009900">Req</span>} <span style="color: #990000">-></span> {<span style="color: #FF6600">ok</span>, <span style="color: #990000"><<</span> <span style="color: #009900">Acc</span><span style="color: #990000">/</span><span style="font-weight: bold"><span style="color: #000080">binary</span></span>, <span style="color: #009900">Data</span><span style="color: #990000">/</span><span style="font-weight: bold"><span style="color: #000080">binary</span></span> <span style="color: #990000">>></span>, <span style="color: #009900">Req</span>};
{<span style="color: #FF6600">more</span>, <span style="color: #009900">Data</span>, <span style="color: #009900">Req</span>} <span style="color: #990000">-></span> <span style="font-weight: bold"><span style="color: #000000">read_body</span></span>(<span style="color: #009900">Req</span>, <span style="color: #990000"><<</span> <span style="color: #009900">Acc</span><span style="color: #990000">/</span><span style="font-weight: bold"><span style="color: #000080">binary</span></span>, <span style="color: #009900">Data</span><span style="color: #990000">/</span><span style="font-weight: bold"><span style="color: #000080">binary</span></span> <span style="color: #990000">>></span>)
<span style="font-weight: bold"><span style="color: #0000FF">end</span></span><span style="color: #990000">.</span></tt></pre></div></div>
<div class="listingblock">
<div class="title">Read the body in small chunks</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><span style="font-weight: bold"><span style="color: #000000">cowboy_req:read_body</span></span>(<span style="color: #009900">Req</span>, #{<span style="font-weight: bold"><span style="color: #000080">length</span></span> <span style="color: #990000">=></span> <span style="color: #993399">64000</span>})<span style="color: #990000">.</span></tt></pre></div></div>
</div>
</div>
<div class="sect1">
<h2 id="_see_also">See also</h2>
<div class="sectionbody">
<div class="paragraph"><p><a href="../cowboy_req">cowboy_req(3)</a>,
<a href="../cowboy_req.has_body">cowboy_req:has_body(3)</a>,
<a href="../cowboy_req.body_length">cowboy_req:body_length(3)</a>,
<a href="../cowboy_req.read_urlencoded_body">cowboy_req:read_urlencoded_body(3)</a>,
<a href="../cowboy_req.read_part">cowboy_req:read_part(3)</a>,
<a href="../cowboy_req.read_part_body">cowboy_req:read_part_body(3)</a></p></div>
</div>
</div>
</div>
<div class="span3 sidecol">
<h3>
Cowboy
2.0
Function Reference
</h3>
<ul>
<li><a href="/docs/en/cowboy/2.0/guide">User Guide</a></li>
<li><a href="/docs/en/cowboy/2.0/manual">Function Reference</a></li>
</ul>
<h4 id="docs-nav">Navigation</h4>
<h4>Version select</h4>
<ul>
<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>
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