Find_all wierdness

Ruby
1

My problem is as follows:

book.chapters.find_all{ |chapter| !chapter.pages.empty? }.size

Theoretically it should return a number of chapters that have pages in
them. However it doesn’t do that at all. It simply returns a number of
all chapters.

On the same note:

book.chapters.find_all { |chapter| chapter.pages.empty? }.size returns
the same thing as above.

Identically

book.chapters.find_all { |chapter| 1 == 2 }.size still returns same
thing (shouldn’t that be zero now???)

And finally

book.chapters.find_all{ my ass }.size returns exactly the same thing!!!
Seems that whatever is in brackets is simply ignored.

Any ideas why it does that? BTW, it seems to work just fine for
numerical arrays.

Thanks.

2

Oleg Kh wrote:

book.chapters.find_all { |chapter| chapter.pages.empty? }.size returns
Seems that whatever is in brackets is simply ignored.

Any ideas why it does that? BTW, it seems to work just fine for
numerical arrays.

Thanks.

–
Posted via http://www.ruby-forum.com/.
Can you send any more context for your use? I’ve used find_all on many
types of arrays w/ .size appended to a block and have no problems with
it. Just ran a couple of IRB tests too and all’s well. Could it be
that your book.chapters is really empty? Have you tried adding a print
to your block to ensure its ever being called. Notice that you change
the block contents and always get the same result: this implies to me
the block is not the issue but what the enumerable has in it, if
anything is.

Cheers,

Ken

3

Daniel DeLorme wrote:

Try to use select instead of find_all. In this case I think you are
actually
triggering ActiveRecord’s find_all instead of the Enumerable#find_all
that you
were expecting. book.chapters is not an array but an association object.
The
ActiveRecord version is defined as:
Project#milestones.find_all(conditions)
So in your case, you don’t give any conditions as parameters and the
method just
ignores the block and returns all chapters. Sometimes Rails magic can
bite you
in the ass.

Daniel

Thank you Daniel. That was it.

4

Oleg Kh wrote:

My problem is as follows:

book.chapters.find_all{ |chapter| !chapter.pages.empty? }.size

Theoretically it should return a number of chapters that have pages in
them. However it doesn’t do that at all. It simply returns a number of
all chapters.

Try to use select instead of find_all. In this case I think you are
actually
triggering ActiveRecord’s find_all instead of the Enumerable#find_all
that you
were expecting. book.chapters is not an array but an association object.
The
ActiveRecord version is defined as:
Project#milestones.find_all(conditions)
So in your case, you don’t give any conditions as parameters and the
method just
ignores the block and returns all chapters. Sometimes Rails magic can
bite you
in the ass.

Daniel