Re: [Rails] Implementing a tagging system in Rails

[Jim Ruther Nill]

On Fri, Apr 22, 2011 at 10:20 PM, Kevin Pang  wrote:

> Just to be sure though, I've changed that line to be:
>
> tags.clear
>

this sure make things clearer. i should've checked the api before i
commented.


>
> This seems cleaner anyways, and the Rails API explicitly states that
> calling this will not delete the objects themselves, only the association.
>
> --
> You received this message because you are subscribed to the Google Groups
> "Ruby on Rails: Talk" group.
> To post to this group, send email to rubyonrails-talk@googlegroups.com.
> To unsubscribe from this group, send email to
> rubyonrails-talk+unsubscr...@googlegroups.com.
> For more options, visit this group at
> http://groups.google.com/group/rubyonrails-talk?hl=en.
>



-- 
-
visit my blog at http://jimlabs.heroku.com

-- 
You received this message because you are subscribed to the Google Groups "Ruby 
on Rails: Talk" group.
To post to this group, send email to rubyonrails-talk@googlegroups.com.
To unsubscribe from this group, send email to 
rubyonrails-talk+unsubscr...@googlegroups.com.
For more options, visit this group at 
http://groups.google.com/group/rubyonrails-talk?hl=en.

Re: [Rails] Implementing a tagging system in Rails

[Kevin Pang]

Just to be sure though, I've changed that line to be:

tags.clear

This seems cleaner anyways, and the Rails API explicitly states that calling 
this will not delete the objects themselves, only the association.

-- 
You received this message because you are subscribed to the Google Groups "Ruby 
on Rails: Talk" group.
To post to this group, send email to rubyonrails-talk@googlegroups.com.
To unsubscribe from this group, send email to 
rubyonrails-talk+unsubscr...@googlegroups.com.
For more options, visit this group at 
http://groups.google.com/group/rubyonrails-talk?hl=en.

Re: [Rails] Implementing a tagging system in Rails

[Kevin Pang]

I don't think this is true. According to the Rails 
API,
 
this is what collection.delete does with a has_and_belongs_to_many 
association:

"Removes one or more objects from the collection by removing their 
associations from the join table. This does not destroy the objects."

I went ahead and tested this out just to make sure and sure enough, only the 
association was deleted when I called save, not the tag itself.

-- 
You received this message because you are subscribed to the Google Groups "Ruby 
on Rails: Talk" group.
To post to this group, send email to rubyonrails-talk@googlegroups.com.
To unsubscribe from this group, send email to 
rubyonrails-talk+unsubscr...@googlegroups.com.
For more options, visit this group at 
http://groups.google.com/group/rubyonrails-talk?hl=en.

Re: [Rails] Implementing a tagging system in Rails

[Jim Ruther Nill]

On Fri, Apr 22, 2011 at 8:09 AM, Kevin Pang  wrote:

> This is a copy/paste from my question over at 
> StackOverflowso
>  feel free to answer there if you want some reputation.
>
> I'm trying to implement a tagging system in a Rails app similar to the one
> StackOverflow uses (where users enter in tags in a freeform textbox). I'm
> aware that there are gems that can do this, but I wanted to try to implement
> it myself for the learning experience. I got it to work, but since I'm a
> Rails newbie I'm concerned I'm not doing it the "right way".
>
> Here's my current implementation:
>
> def Post
>   attr_accessor :tag_names
>
>   has_and_belongs_to_many :tags
>
>   after_save :update_tags
>
>   private
> def update_tags
>   tags.delete_all
>
>   if tag_names.to_s == ''
> return
>   end
>
>   tag_names.split(/,/).each do |tag_name|
> tag_name.strip!
> tag = Tag.find_or_create_by_name(tag_name)
>
> if !tags.exists?(tag.id)
>   tags << tag
> end
>   end
> end
> end
>
> This makes it easy for me to set up the tags for a post since all I have to
> do is set the "tag_names" attribute on my post object. When I save the post
> object, the after_save event fires and executes my update_tags function
> which then handles creating tags and linking the post to them.
>
> Are there any problems with my implementation?
>
>
>
You're deleting the tag records on every save. So other posts which belong
to the tags you deleted would
most probably throw an error when you try to access the tags (or will they
silently update the the post's tags?).

Anyway, you need to have access to the join table and delete the records
created there instead of deleting
the tag records when updating the post record.

I don't know if it would improve performance, but instead of deleting all
tags of the post, why not compare the
post's current tags first and create/associate a tag to the post if it's not
yet associated?


>  --
> You received this message because you are subscribed to the Google Groups
> "Ruby on Rails: Talk" group.
> To post to this group, send email to rubyonrails-talk@googlegroups.com.
> To unsubscribe from this group, send email to
> rubyonrails-talk+unsubscr...@googlegroups.com.
> For more options, visit this group at
> http://groups.google.com/group/rubyonrails-talk?hl=en.
>



-- 
-
visit my blog at http://jimlabs.heroku.com

-- 
You received this message because you are subscribed to the Google Groups "Ruby 
on Rails: Talk" group.
To post to this group, send email to rubyonrails-talk@googlegroups.com.
To unsubscribe from this group, send email to 
rubyonrails-talk+unsubscr...@googlegroups.com.
For more options, visit this group at 
http://groups.google.com/group/rubyonrails-talk?hl=en.