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POMongoDB--add/drop elements in a field of array of hash how to
 

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    <p>I am using perl MongoDBx::Class, following the tutorial I inserted the document below. The tags field is an array of hash. Tried to remove tag and add tag using mongodb's $pull and $addToSet function without success. </p> <p>How to add/drop elements to/from tags field? If you are not a perl programmer, answer in mongodb shell command also wlcome.</p> <p>Thanks.</p> <pre><code>my $novel = $novels_coll-&gt;insert({ _class =&gt; 'Novel', title =&gt; 'The Valley of Fear', year =&gt; 1914, author =&gt; { first_name =&gt; 'Arthur', middle_name =&gt; 'Conan', last_name =&gt; 'Doyle', }, added =&gt; DateTime-&gt;now(time_zone =&gt; 'Asia/Jerusalem'), tags =&gt; [ { category =&gt; 'mystery', subcategory =&gt; 'thriller' }, { category =&gt; 'mystery', subcategory =&gt; 'detective' }, { category =&gt; 'crime', subcategory =&gt; 'fiction' }, ], }); </code></pre> <p>This is the document inserted:</p> <pre><code>{ "_id": { "$oid": "4e27eae3008a6ee40f000000" }, "_class": "Novel", "added": "2011-07-21T12:01:23+03:00", "author": { "middle_name": "Conan", "last_name": "Doyle", "first_name": "Arthur" }, "tags": [ { "subcategory": "thriller", "category": "mystery" }, { "subcategory": "detective", "category": "mystery" }, { "subcategory": "fiction", "category": "crime" } ], "title": "The Valley of Fear", "year": 1914 } </code></pre> <p>Edit: </p> <p>After deeper exploration of MongoDBX, the update method overrided offical MongoDB driver, so the $pull, $addToSet may not work. I will use this stupid method:</p> <pre><code>my $novel = $novel_coll-&gt;find_one({ some criteria }); my @tags = $novel-&gt;tags; my @updated_tags = grep(unless($tag{category=&gt;CATEGORY}, @tags); #to pull out unwanted tag. Or use push to add new tag. $novel-&gt;update({tags=&gt;\@updated_tags}); </code></pre> <p>I hope MongoDBx has method to updated arrayRef field.</p>
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