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PORecursion tree on Ruby on Rails
 

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  1. PORecursion tree on Ruby on Rails
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    <p>Following is the iterative tree, done in html.erb, which reaches only two levels in a tree structure:</p> <pre><code> &lt;ul&gt; &lt;li&gt;&lt;%= root_template.id %&gt;&lt;/li&gt; &lt;ul&gt; &lt;% for template in root_template.children %&gt; &lt;li&gt;&lt;%= template.id %&gt;&lt;/li&gt; &lt;% if template.has_children? %&gt; &lt;ul&gt; &lt;% for template_child in template.children %&gt; &lt;li&gt;&lt;%= template_child.id %&gt;&lt;/li&gt; &lt;% end %&gt; &lt;/ul&gt; &lt;% end %&gt; &lt;% end %&gt; &lt;/ul&gt; &lt;/ul&gt; </code></pre> <p>Result: <img src="https://i.stack.imgur.com/qFx1a.png" alt="iterative"></p> <p>I wanted to move the code in the helper files and apply a recursion to reach all the levels:</p> <p>html.erb (so, setting the root from template):</p> <pre><code> &lt;% html = '' %&gt; &lt;ul&gt; &lt;li&gt;&lt;%= root_template.id %&gt;&lt;/li&gt; &lt;ul&gt; &lt;%= recursive_tree root_template, html %&gt; &lt;/ul&gt; &lt;/ul&gt; </code></pre> <p>Then helper method:</p> <pre><code> def recursive_tree(root, html) html &lt;&lt; '' if !root.has_children? html &lt;&lt; "&lt;li&gt;#{root.id}&lt;/li&gt;" return html.html_safe else for template_child in root.children html &lt;&lt; "&lt;ul&gt;#{recursive_tree(template_child, html)}&lt;/ul&gt;" end end return html.html_safe end </code></pre> <p>Result:<img src="https://i.stack.imgur.com/lqXic.png" alt="Wrong Recursive Result"></p> <p>I already spent a day to figure out how to send proper html from helper to template, now couldn't figure out what is the issue with this recursion and the solution even I used a debugger. Is there any opinion?</p>
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    1. COResults seem identical. What's the problem?
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      1. USHelio Santos
    2. CO@HélioSantos I've corrected the first image.
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