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PODynamically creating a multi-dimensional hash in Ruby
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copied!<p>I'm a PHP developer who's trying to gain some proficiency in Ruby. One of the projects I'm cutting my teeth on now is a source-code auditing tool that scans webapp files for potentially dangerous functions in several web programming languages. When matches are found, the script saves the relevant information in a <code>poi</code> (point-of-interest) class for display later on.</p> <p>An example instance of that class would look something like this (modeled in YAML):</p> <pre><code>poi: file_type: "php" file: "the-scanned-file.php" line_number: 100 match: "eval()" snippet: "echo eval()" </code></pre> <p>On display, I want to organize these points of interest like so:</p> <pre><code>- file_type -- file --- match (the searched payload) </code></pre> <p>Thus, before presentation, I'm trying to structure a flat array of <code>poi</code> objects into a hash mirroring the structure above. This will allow me to simply iterate over the items in the hash to produce the desired on-screen organization. (Or at least, that's the plan.)</p> <p>And now, for my question: how do I do that in Ruby?</p> <p>In PHP, I could do something like this really easily:</p> <pre class="lang-php prettyprint-override"><code><?php $sorted_pois = array(); foreach($points_of_interest as $point){ $sorted_pois[$point->file_type][$point->file][$point->match][] = $point; } ?> </code></pre> <p>I've tried translating that thought from PHP to Ruby like this, but to no avail:</p> <pre><code>sorted_pois = {} @points_of_interest.each_with_index do |point, index| sorted_pois[point.file_type.to_sym][point.file.to_sym][point.match.to_sym].push point end </code></pre> <p>I've spent a few hours on this, and I'm kind of banging my head against the wall at this point, so presumably I'm way off-base. What's the proper way to handle this in Ruby?</p> <p><strong>Update:</strong></p> <p>For reference, this is the precise method I have defined:</p> <pre><code># sort the points of interest into a structured hash def sort sorted_pois = {} @points_of_interest.each_with_index do |point, index| sorted_pois[point.file_type.to_sym][point.file.to_sym][point.match.to_sym].push point end end </code></pre> <p>This is the error I receive when I run the code:</p> <pre><code>./lib/models/vulnscanner.rb:63:in `sort': undefined method `[]' for nil:NilClass (NoMethodError) from /usr/lib/ruby/1.8/rubygems/custom_require.rb:31:in `each_with_index' from ./lib/models/vulnscanner.rb:62:in `each' from ./lib/models/vulnscanner.rb:62:in `each_with_index' from ./lib/models/vulnscanner.rb:62:in `sort' from ./webapp-vulnscan:69 </code></pre> <p>Line 62 (as you can likely infer) is this line in particular:</p> <pre><code>@points_of_interest.each_with_index do |point, index| </code></pre> <p>As an additional reference, here's what (a snippet of) <code>@points_of_interest</code> looks like when converted to YAML:</p> <pre><code>- !ruby/object:PoI file: models/couponkimoffer.php file_type: php group: :dangerous_functions line_number: "472" match: ` snippet: ORDER BY `created_at` DESC - !ruby/object:PoI file: models/couponkimoffer.php file_type: php group: :dangerous_functions line_number: "818" match: ` snippet: WHERE `company_slug` = '$company_slug' - !ruby/object:PoI file: models/couponkimoffer.php file_type: php group: :dangerous_functions line_number: "819" match: ` snippet: ORDER BY `created_at` DESC </code></pre>

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