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            <header><h1><a href="..">Red Tape</a></h1></header>
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<h1 id="initial-data"><a href="">Initial Data</a></h1><p>Sometimes you want to provide sane defaults for fields in a form.  To do this
you can use the <code>:initial</code> entry in the <code>defform</code> option map.  For example:</p>
<div class="codehilite"><pre><span class="p">(</span><span class="nf">defform</span> <span class="nv">sample-form</span> <span class="p">{</span><span class="ss">:initial</span> <span class="p">{</span><span class="ss">:email</span> <span class="s">"user@example.com"</span><span class="p">}}</span>
  <span class="ss">:email</span> <span class="p">[]</span>
  <span class="ss">:message</span> <span class="p">[])</span>
</pre></div>


<p>When creating a fresh form, this initial data will populate the <code>:data</code> map in
the result instead of the default empty string:</p>
<div class="codehilite"><pre><span class="p">(</span><span class="nf">sample-form</span><span class="p">)</span>
<span class="c1">; =&gt;</span>
<span class="p">{</span><span class="ss">:fresh</span> <span class="nv">true</span>
 <span class="ss">:results</span> <span class="nv">nil</span>
 <span class="ss">:data</span> <span class="p">{</span><span class="ss">:email</span> <span class="s">"user@example.com"</span>
        <span class="ss">:message</span> <span class="s">""</span><span class="p">}</span>
 <span class="nv">...</span><span class="p">}</span>
</pre></div>


<p>When you run some data through the form, the initial data is ignored completely:</p>
<div class="codehilite"><pre><span class="p">(</span><span class="nf">sample-form</span> <span class="p">{</span><span class="ss">:email</span> <span class="s">"foo@bar.com"</span>
              <span class="ss">:message</span> <span class="s">"hi"</span><span class="p">})</span>
<span class="c1">; =&gt;</span>
<span class="p">{</span><span class="ss">:fresh</span> <span class="nv">false</span>
 <span class="ss">:results</span> <span class="p">{</span><span class="ss">:email</span> <span class="s">"foo@bar.com"</span>
           <span class="ss">:message</span> <span class="s">"hi"</span><span class="p">}</span>
 <span class="ss">:data</span>    <span class="p">{</span><span class="ss">:email</span> <span class="s">"foo@bar.com"</span>
           <span class="ss">:message</span> <span class="s">"hi"</span><span class="p">}</span>
 <span class="nv">...</span><span class="p">}</span>
</pre></div>


<p>This means when you're rendering a form field to HTML you can simply pull the
field's entry from the <code>:data</code> map and fill the field with its contents.  It
doesn't matter whether it happened to be a fresh form or a form that had some
errors.</p>
<p>Note that initial data should always be specified as a string, since the <code>:data</code>
map will always contain strings once you've run data through it.</p>
<p>Move on to the <a href="../form-arguments/">form arguments</a> guide next.</p>
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author	Steve Losh <steve@stevelosh.com>
date	Mon, 23 Dec 2019 16:18:40 -0500
parents	69831b3947d7
children	(none)