Regarding queries across relationships

Rails
1

Hi, I’m sending this message again due to the migrationof the list…

I’m trying to build a query that looks like this:

 @book_pages, @books = paginate(:books,
                                            :per_page => 20,
                                            :conditions =>

[‘book.author.name like ?’, '%jim%],
:order_by =>
@sort_order)

I want to basically list out all the books by authors with names like
‘jim’ - prefer to have this paginated so that I can use my basic
paginated list view. However, this throws up an exception:

Mysql::Error: Unknown table ‘books’ in where clause: SELECT count(*) AS
count_all FROM books WHERE (author.name like ‘%ha%’)

My models:
authors have_many books
book belongs_to author

I’m sorry I seem very confused about how to do the query. I’d
appreciate help!

What do you think I’m doing wrong?
Thanks
Mohit.

2

Mohit S. wrote:

Hi, I’m sending this message again due to the migrationof the list…

I’m trying to build a query that looks like this:

 @book_pages, @books = paginate(:books,
                                            :per_page => 20,
                                            :conditions =>

[‘book.author.name like ?’, '%jim%],
:order_by => @sort_order)

hi,
I’m working on a book app to !
thats how it should look like :
—>> paginate(:book, :include=>[:author], …,
:conditions=>[“authors.name like ?”, ‘%jim%’])
the include statement operates a join in the sql query. See eager
loading for more explanations.

3

Mohit S. wrote:

Hi, I’m sending this message again due to the migrationof the list…

I’m trying to build a query that looks like this:

 @book_pages, @books = paginate(:books,
                                            :per_page => 20,
                                            :conditions =>

[‘book.author.name like ?’, '%jim%],
:order_by => @sort_order)

hi,
I’m working on a book app to !
thats how it should look like :
—>> paginate(:book, :include=>[:author], …, :conditions=>[“authors
like ?”, ‘%jim%’])
the include statement operates a join in the sql query. See eager
loading for more explanations.

4

[email protected] wrote:

                                            :order_by => @sort_order)

Thanks! I actually just figured that out and was going to mail out a
reply to my own post.

I guess my confusion came from the fact that I had not found a good
example of a join query. Also, the impression that I had got from
somewhere was that “:include” is used to load all the data in a single
query (which stuck in my mind as an ‘optimization’ rather than a
must-do). My rules for optimization require me to do that only at the
end. Hence, it was failing… but I understand now!

Thanks again & sorry for the bother. :slight_smile:
Cheers
Mohit.