Rails - Feb 2007 - ruby on rails syntax

Hi everyone, simple syntax question that is confusing me.
I have the folowing method im my controller:

  def archive
    @posts = Post.find(:all, :conditions => ["YEAR(created_at) = ? and
MONTH(created_at) = ?",  params[:year], params[:month]])
  end

which works fine.

but if use similar code in my view, it does not work, e.g

<%= YEAR(post.created_at) %>

i have to use this code in my view:

<%= post.created_at.year %>

But likewise, if use this line in my controller, it does not work:

  def archive
    @posts = Post.find(:all, :conditions => ["created_at.year = ? and
created_at.month = ?",  params[:year], params[:month]])
  end

can anyone explain this to me please?

many thanks

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Hi --

On Sat, 24 Feb 2007, Jon wrote:
> Hi everyone, simple syntax question that is confusing me.
> I have the folowing method im my controller:
>
>  def archive
>    @posts = Post.find(:all, :conditions => ["YEAR(created_at) = ?
and
> MONTH(created_at) = ?",  params[:year], params[:month]])
>  end
>
> which works fine.
>
> but if use similar code in my view, it does not work, e.g
>
> <%= YEAR(post.created_at) %>
>
> i have to use this code in my view:
>
> <%= post.created_at.year %>
>
> But likewise, if use this line in my controller, it does not work:
>
>  def archive
>    @posts = Post.find(:all, :conditions => ["created_at.year = ?
and
> created_at.month = ?",  params[:year], params[:month]])
>  end
>
> can anyone explain this to me please?
The :conditions clause in ActiveRecord uses SQL, not Ruby.  The string
interpolation (<%= ... %>) in ERb uses Ruby, not SQL.  So you need to
use both, depending on the requirements of the given library.


David

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Thank you David, so the month functions being called are in fact 
different functions?

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Jon wrote:
> Thank you David, so the month functions being called are in fact 
> different functions?
Yes.

When you do this:

  Post.find(:all, :conditions => ["YEAR(created_at) = ? and
    MONTH(created_at) = ?",  params[:year], params[:month]])

Rails sends a query like this to the database:

  SELECT * FROM posts WHERE
    YEAR(created_at) = ''2007'' and
    MONTH(created_at) = ''02''

Your database responds with whatever is appropriate to that query.  The 
YEAR and MONTH function in that query are interpreted and execute by the 
database, rails just passes it along.  Rails has no idea what that query 
really means, it just collects the result.

When you do:

  <%= YEAR(post.created_at) %>

Rails will look for a ruby method called "YEAR" and send it an
argument
of a Time object.  Ruby does not find a method called "YEAR" and
throws
an exception.

You probably want something more like:

  <%= post.created_at.year %>

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got it! thanks guys.

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