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POHow to check if a record exists before creating a new one in rails3?
 

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  1. POHow to check if a record exists before creating a new one in rails3?
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    <p>Heres what I'm trying to accomplish: </p> <ul> <li>I have a tagging system in place. </li> <li>Tags are created, when Posts are created (posts has_many :tags, :through => :tag_joins. </li> <li>A tag join is automatically created when a post is created with tags). </li> </ul> <p>I want to check if the tag already exists. If it does I want to use the existing tag for the tag_join record, rather than creating a new tag record.</p> <p>Here is my current code, which isn't working.</p> <pre><code>class Tag &lt; ActiveRecord :: Base belongs_to :user belongs_to :tag_join belongs_to :post before_create :check_exists def check_exists tag = Tag.where(:name =&gt; self.name, :user_id =&gt; current_user.id) if tag.nil? tag = Tag.create(:name =&gt; self.name, :user_id =&gt; current_user.id) end end end </code></pre> <p>This doesn't work though, I'm getting an error upon task creation...(the server is actually just timing out - I don't receive a specific error).</p> <p>Any ideas?</p> <p>Tokland said I was creating an infinite loop by telling it to create tag again - so I tried this:</p> <pre><code> def check_exists tag = Tag.find_by_name_and_user_id(:name =&gt; self.name, :user_id =&gt; current_user.id) if tag != nil self.id = tag.id end end </code></pre> <p>And still get the server timeout</p> <p>Edit: I'm not sure if this matters, but the way the tags are being added is similar to "http://railscasts.com/episodes/73-complex-forms-part-1</p> <p>they're nested in the post form, and use something like this:</p> <pre><code>def tag_attributes=(tag_attributes) tag_attributes.each do |attributes| tags.build(attributes) end end </code></pre> <p>I'm wondering if this is stopping this whole thing from working? Also, using current_user.id in the model definitely seems to be an issue...</p> <p><strong>EDIT:</strong></p> <p>Something I have figured out: this had to change, the format we were using before was incorrect syntax - generally used for a .where method.</p> <pre><code> def check_exists @tag = Tag.find_by_name_and_user_id(self.name, self.user_id) if @tag != nil #return false #self=@tag end end </code></pre> <p>The problem now is this, I can learn if it the tag already exists. But then what? If I go with the return false option, there is an error upon post creation, and the join record isn't created... The other option "self=@tag" obviously just doesn't work.</p>
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      1. POHow to check if a record exists before creating a new one in rails3?
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    1. COCode review time: When naming routines, you want to use a name that is indicative of what it does. Calling a method "check_exists" when it could actually be creating records could make it harder to find "where'd that record come from?" once you've got a lot of code in an app. Maybe "get_tag" or "find_or_create_tag" would be better? Subtle things like this add up in an app and determine its readability and maintainability over time.
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    2. COThe server timeout is probably not related to the code. Check to see whether it's actually running, and, if it's on another machine, whether you have connectivity to it.
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    3. COIts actually just happening in my local environment. The server freezes up everytime I try to create a tag even manually through rails admin.
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