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POShow image upload preview with Lift
 

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    <p>I want to upload an image with Lift and show it immediatly in some element of the page, without reloading. I want to do it like in <a href="http://www.9lessons.info/2011/08/ajax-image-upload-without-refreshing.html" rel="nofollow">this</a> solution (which uses PHP).</p> <p>The process there is comparatedly simple. I replaced the PHP file with a dummy HTML snippet:</p> <pre><code>&lt;form id="imageform" method="post" enctype="multipart/form-data" action="ajaximage.html"&gt; &lt;input id="imageFile" name="imageFile" type="file" size="50" maxlength="100000"/&gt; &lt;/form&gt;&lt;br/&gt; &lt;script src="jquery-1.8.3.min.js"&gt;&lt;/script&gt; &lt;script src="jquery.form.js"&gt;&lt;/script&gt; &lt;script type="text/javascript"&gt; $(document).ready(function() { $('#imageFile').live('change', function() { $("#preview").html(''); $("#preview").html('&lt;img src="images/processing.jpg" alt="Uploading...."/&gt;'); $("#imageform").ajaxForm({ target : '#preview' }).submit(); }); }); &lt;/script&gt; </code></pre> <p>The HTML snippet:</p> <pre><code>&lt;img src="images/someimage.jpg"/&gt; </code></pre> <p>Well, this works. But I need dynamic behaviour obviously. The example page is using instead of my HTML snippet a PHP file, which extracts the data from the request, saves it in the server, and outputs the HTML for the preview image accordingly - <code>echo "&lt;img src='uploads/".$actual_image_name."' class='preview'&gt;";</code></p> <p>Now, I have no idea how to accomplish this with Lift.</p> <p>I found this discussion: <a href="https://groups.google.com/forum/?fromgroups=#!topic/liftweb/6bxNlbBPJvE" rel="nofollow">https://groups.google.com/forum/?fromgroups=#!topic/liftweb/6bxNlbBPJvE</a> But no good solution there besides a vague advice for a framework and HTML5 things which I don't want to use.</p> <hr> <p><strong>Part 2</strong>. I have, already implemented some basics for this in Lift:</p> <p>HTML:</p> <pre><code>&lt;div class="lift:AddImage.addEntry" form="POST" multipart="true"&gt; &lt;p&gt;&lt;prefix:imageUpload/&gt;&lt;/p&gt; &lt;p&gt;&lt;prefix:test/&gt;&lt;/p&gt; &lt;/div&gt; </code></pre> <p>snippet:</p> <pre><code>package code package snippet import net.liftweb.http.S import net.liftweb.common.Full import net.liftweb.common.Empty import net.liftweb.common.Box import net.liftweb.http.FileParamHolder import net.liftweb.util._ import Helpers._ import scala.xml.Group import scala.xml.NodeSeq import net.liftweb.http.SHtml import javax.annotation.Resource import java.io.OutputStream import java.io.FileOutputStream class AddImage { // Add a variable to hold the FileParamHolder on submission var fileHolder : Box[FileParamHolder] = Empty def submitTest () { println("submitTest called!") val receiptOk = fileHolder match { // An empty upload gets reported with a null mime type, // so we need to handle this special case case Full(FileParamHolder(_, null, _, _)) =&gt; true case Full(FileParamHolder(_, mime, _, data)) =&gt; println("MIME: " + mime) if (mime.startsWith("image/")) { println("uploading the image: ") //scala.io.Source.fromBytes(data) try { val out: OutputStream = new FileOutputStream("test.jpg"); out.write(data); out.flush(); out.close(); } catch { case e: Exception =&gt; println("Exception!: " + e) } true } case Full(_) =&gt; { S.error("Invalid attachment") false } case _ =&gt; true } // (e.validate, receiptOk) match { // } } def addEntry(content: NodeSeq): NodeSeq = { bind("prefix", content, "imageUpload" -&gt; SHtml.fileUpload(f =&gt; fileHolder = Box !! f), "test" -&gt; SHtml.submit("submitz", submitTest)) } } </code></pre> <p>But I'm stuck here because:</p> <ul> <li><p>I don't know how to reference the form created by Lift from jquery.</p></li> <li><p>The javascript submits the form when the upload input field changes, with <code>ajaxForm()</code> and inserts the result of the PHP script in the <code>#preview</code> element. I don't know how to get the form submit in scala and further output the image HTML, such that it can be inserted in <code>#preview</code></p></li> </ul> <p>Hope this is not to much questions :) thanks in advance.</p>
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