It's calling an extra query and leaving it there:
"first query
~ (0.000097) SELECT "id", "age", "name" FROM "users" ORDER BY "age"
["Jill", "Mary", "Bob", "Jack"]
"Jack"
["Jill", "Mary", "Bob", "Jack"]
second query
~ (0.000081) SELECT "id", "age", "name" FROM "users" ORDER BY "age"
DESC LIMIT 1
"Jack"
~ (0.000078) SELECT "id", "age", "name" FROM "users" ORDER BY "age"
DESC
["Bob", "Mary", "Jill", "Jack"]"
I don't think it is a bug, here's how it works:
"s = User.all(:order => [:age.asc])"
"s" is just a DataMapper::Query until you call something on it.
"s.map{|r| r.name}" <- now you've called something so the query
executes here.
"s" is now a reference to a DataMapper::Collection, because you called
the query
"s.last.name" -> #last is calling DataMapper::Collection#last
In the second part:
"s = User.all(:order => [:age.asc])"
"s" again is just a query at this point
"s.last.name" the query is updated with #last, so now the query is
like this: User.all(:order => [:age.asc]).last => which is like
User.all(:order => [:age.asc]).update(:limit => 1, :order =>
[:age.desc]) because DM will give you the "last result in users sorted
by age asc" which is the same as saying the "first result in users
sorted by age desc"
Here's how it -might- be a bug... (in the second example)
"s" is a reference to an updated query as opposed to a single User
instance, or it might be a collection, I don't know here...
"s.map{|r| r.name}" #map is being called on the updated query
On Feb 28, 11:01 pm, MarkMT <mark.thom...@ieee.org> wrote:
> Sorry, I pasted the url for another gist I had been looking at from a
> different thread. This is the one I meant to refer to -
>
> http://gist.github.com/318072
>
> On Feb 28, 10:57 pm, MarkMT <mark.thom...@ieee.org> wrote:
>
>
>
> > I've run into a problem that seems like it might be a bug...
>
> > If I retrieve a set of records using the ':order' option and then call
> > 'last' on the resulting collection, the collection seems to end up
> > being mis-ordered. The problem only seems to manifest itself if I
> > haven't made an attempt to do anything with the ordered collection
> > prior to calling 'last'.
>
> > Here's a gist that illustrates -http://gist.github.com/305019.
>
> > This is with dm 0.10.2. Am I misunderstanding how this should work?
>
> > Mark.
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