Re: [DataMapper] get previous/next item in database
Yeah, it works with the .last. I might switch to the :id. Thanks Kristian and Ben! You rock! Alex -- You received this message because you are subscribed to the Google Groups "DataMapper" group. To view this discussion on the web visit https://groups.google.com/d/msg/datamapper/-/lBuXyCjxdcoJ. To post to this group, send email to datamapper@googlegroups.com. To unsubscribe from this group, send email to datamapper+unsubscr...@googlegroups.com. For more options, visit this group at http://groups.google.com/group/datamapper?hl=en.
Re: [DataMapper] get previous/next item in database
is a pleasure :)) -- You received this message because you are subscribed to the Google Groups "DataMapper" group. To post to this group, send email to datamapper@googlegroups.com. To unsubscribe from this group, send email to datamapper+unsubscr...@googlegroups.com. For more options, visit this group at http://groups.google.com/group/datamapper?hl=en.
Re: [DataMapper] get previous/next item in database
On 22 January 2013 17:51, kristian wrote: > be aware that timestamps are not unique, i.e. they usually have no > millis or nanos. just a thought whether using them to iterate over > them. > > - Kristian > > On Tue, Jan 22, 2013 at 11:16 PM, kristian wrote: > > take last instead of first :) > > > >> Audit.last( :id.lt => 10 ) > > => # > > > - Kristian > > > Heh, first time I've ever participated in pair-programming via email :) Cheers, Ben > > On Tue, Jan 22, 2013 at 10:43 PM, Alex wrote: > >> Thanks guys, the code works, however there is a problem. The .gt works > fine, > >> but the .lt always gives me the first element in the db, not the > previous > >> element! I tried it with both the :id (@post_id) and the :created_on > >> (@post_date) properties, getting the same result: > >> > >>> def post_in_db > >>> posts_of_user.each do |post| > >>> if post.slug == params[:post_slug] > >>> @post_slug ||= post.slug > >>> @post_title ||= post.title > >>> @post_body ||= post.body > >>> @post_date ||= post.created_on > >>> @post_private ||= post.private > >>> @post_id ||= post.id > >>> @previous = prev.title > >>> @next = nexts.title > >>> end > >>> end > >>> end > >>> def prev > >>> Post.first(:created_on.lt => @post_date) > >>> end > >>> def nexts > >>> Post.first(:created_on.gt => @post_date) > >>> end > >> > >> > >> Any ideas? > >> > >> -- > >> You received this message because you are subscribed to the Google > Groups > >> "DataMapper" group. > >> To view this discussion on the web visit > >> https://groups.google.com/d/msg/datamapper/-/278-qTqCbrsJ. > >> > >> To post to this group, send email to datamapper@googlegroups.com. > >> To unsubscribe from this group, send email to > >> datamapper+unsubscr...@googlegroups.com. > >> For more options, visit this group at > >> http://groups.google.com/group/datamapper?hl=en. > > -- > You received this message because you are subscribed to the Google Groups > "DataMapper" group. > To post to this group, send email to datamapper@googlegroups.com. > To unsubscribe from this group, send email to > datamapper+unsubscr...@googlegroups.com. > For more options, visit this group at > http://groups.google.com/group/datamapper?hl=en. > > -- You received this message because you are subscribed to the Google Groups "DataMapper" group. To post to this group, send email to datamapper@googlegroups.com. To unsubscribe from this group, send email to datamapper+unsubscr...@googlegroups.com. For more options, visit this group at http://groups.google.com/group/datamapper?hl=en.
Re: [DataMapper] get previous/next item in database
be aware that timestamps are not unique, i.e. they usually have no millis or nanos. just a thought whether using them to iterate over them. - Kristian On Tue, Jan 22, 2013 at 11:16 PM, kristian wrote: > take last instead of first :) > >> Audit.last( :id.lt => 10 ) > => # > - Kristian > > On Tue, Jan 22, 2013 at 10:43 PM, Alex wrote: >> Thanks guys, the code works, however there is a problem. The .gt works fine, >> but the .lt always gives me the first element in the db, not the previous >> element! I tried it with both the :id (@post_id) and the :created_on >> (@post_date) properties, getting the same result: >> >>> def post_in_db >>> posts_of_user.each do |post| >>> if post.slug == params[:post_slug] >>> @post_slug ||= post.slug >>> @post_title ||= post.title >>> @post_body ||= post.body >>> @post_date ||= post.created_on >>> @post_private ||= post.private >>> @post_id ||= post.id >>> @previous = prev.title >>> @next = nexts.title >>> end >>> end >>> end >>> def prev >>> Post.first(:created_on.lt => @post_date) >>> end >>> def nexts >>> Post.first(:created_on.gt => @post_date) >>> end >> >> >> Any ideas? >> >> -- >> You received this message because you are subscribed to the Google Groups >> "DataMapper" group. >> To view this discussion on the web visit >> https://groups.google.com/d/msg/datamapper/-/278-qTqCbrsJ. >> >> To post to this group, send email to datamapper@googlegroups.com. >> To unsubscribe from this group, send email to >> datamapper+unsubscr...@googlegroups.com. >> For more options, visit this group at >> http://groups.google.com/group/datamapper?hl=en. -- You received this message because you are subscribed to the Google Groups "DataMapper" group. To post to this group, send email to datamapper@googlegroups.com. To unsubscribe from this group, send email to datamapper+unsubscr...@googlegroups.com. For more options, visit this group at http://groups.google.com/group/datamapper?hl=en.
Re: [DataMapper] get previous/next item in database
take last instead of first :) > Audit.last( :id.lt => 10 ) => # wrote: > Thanks guys, the code works, however there is a problem. The .gt works fine, > but the .lt always gives me the first element in the db, not the previous > element! I tried it with both the :id (@post_id) and the :created_on > (@post_date) properties, getting the same result: > >> def post_in_db >> posts_of_user.each do |post| >> if post.slug == params[:post_slug] >> @post_slug ||= post.slug >> @post_title ||= post.title >> @post_body ||= post.body >> @post_date ||= post.created_on >> @post_private ||= post.private >> @post_id ||= post.id >> @previous = prev.title >> @next = nexts.title >> end >> end >> end >> def prev >> Post.first(:created_on.lt => @post_date) >> end >> def nexts >> Post.first(:created_on.gt => @post_date) >> end > > > Any ideas? > > -- > You received this message because you are subscribed to the Google Groups > "DataMapper" group. > To view this discussion on the web visit > https://groups.google.com/d/msg/datamapper/-/278-qTqCbrsJ. > > To post to this group, send email to datamapper@googlegroups.com. > To unsubscribe from this group, send email to > datamapper+unsubscr...@googlegroups.com. > For more options, visit this group at > http://groups.google.com/group/datamapper?hl=en. -- You received this message because you are subscribed to the Google Groups "DataMapper" group. To post to this group, send email to datamapper@googlegroups.com. To unsubscribe from this group, send email to datamapper+unsubscr...@googlegroups.com. For more options, visit this group at http://groups.google.com/group/datamapper?hl=en.
Re: [DataMapper] get previous/next item in database
Thanks a lot, Ben! Got it working by ordering the one in descending and the other in ascending order: def prev > Post.first(:created_on.lt => @post_date, :order => [:created_on.desc]) > end > def nexts > Post.first(:created_on.gt => @post_date, :order => [:created_on.asc]) > end Thanks guys, Alex -- You received this message because you are subscribed to the Google Groups "DataMapper" group. To view this discussion on the web visit https://groups.google.com/d/msg/datamapper/-/4yjv3-AV6noJ. To post to this group, send email to datamapper@googlegroups.com. To unsubscribe from this group, send email to datamapper+unsubscr...@googlegroups.com. For more options, visit this group at http://groups.google.com/group/datamapper?hl=en.
Re: [DataMapper] get previous/next item in database
Add some ordering to the posts, this should return the correct records: On 22 January 2013 17:13, Alex wrote: > Thanks guys, the code works, however there is a problem. The .gt works > fine, but the .lt always gives me the first element in the db, not the > previous element! I tried it with both the :id (@post_id) and the > :created_on (@post_date) properties, getting the same result: > > def post_in_db >> posts_of_user.each do |post| >> if post.slug == params[:post_slug] >> @post_slug ||= post.slug >> @post_title ||= post.title >> @post_body ||= post.body >> @post_date ||= post.created_on >> @post_private ||= post.private >> @post_id ||= post.id >> @previous = prev.title >> @next = nexts.title >> end >> end >> end >> def prev >> Post.first(:created_on.lt => @post_date, :order => [:post_date.asc]) >> end >> def nexts >> Post.first(:created_on.gt => @post_date, :order => [:post_date.asc]) >> end > > > Any ideas? > Again, I have to add this is untested gmail code ;) Cheers, Ben -- You received this message because you are subscribed to the Google Groups "DataMapper" group. To post to this group, send email to datamapper@googlegroups.com. To unsubscribe from this group, send email to datamapper+unsubscr...@googlegroups.com. For more options, visit this group at http://groups.google.com/group/datamapper?hl=en.
Re: [DataMapper] get previous/next item in database
Thanks guys, the code works, however there is a problem. The .gt works fine, but the .lt always gives me the first element in the db, not the previous element! I tried it with both the :id (@post_id) and the :created_on (@post_date) properties, getting the same result: def post_in_db > posts_of_user.each do |post| > if post.slug == params[:post_slug] > @post_slug ||= post.slug > @post_title ||= post.title > @post_body ||= post.body > @post_date ||= post.created_on > @post_private ||= post.private > @post_id ||= post.id > @previous = prev.title > @next = nexts.title > end > end > end > def prev > Post.first(:created_on.lt => @post_date) > end > def nexts > Post.first(:created_on.gt => @post_date) > end Any ideas? -- You received this message because you are subscribed to the Google Groups "DataMapper" group. To view this discussion on the web visit https://groups.google.com/d/msg/datamapper/-/278-qTqCbrsJ. To post to this group, send email to datamapper@googlegroups.com. To unsubscribe from this group, send email to datamapper+unsubscr...@googlegroups.com. For more options, visit this group at http://groups.google.com/group/datamapper?hl=en.
Re: [DataMapper] get previous/next item in database
gt == great-than so the previous id you get with previous = Audit.first( :id.lt => current_id ) lt == less-than or lower-than or so and id are unique per definition and they get automatically created by sequence or similar FYI next and previous can be nil ! - Kristian On Tue, Jan 22, 2013 at 5:36 PM, Alex wrote: > @Kristian Thanks, I haven’t tried it yet, but how does that get the next id? > With the :id.gt ? How about the previous id? > > > On Tuesday, January 22, 2013 1:13:51 PM UTC+2, kristian wrote: >> >> what about doing something like this : >> >> current_id = Audit.first.id >> next = Audit.first( :id.gt => current_id ) >> >> - Kristian > > -- > You received this message because you are subscribed to the Google Groups > "DataMapper" group. > To view this discussion on the web visit > https://groups.google.com/d/msg/datamapper/-/bEe_NnzF3MAJ. > > To post to this group, send email to datamapper@googlegroups.com. > To unsubscribe from this group, send email to > datamapper+unsubscr...@googlegroups.com. > For more options, visit this group at > http://groups.google.com/group/datamapper?hl=en. -- You received this message because you are subscribed to the Google Groups "DataMapper" group. To post to this group, send email to datamapper@googlegroups.com. To unsubscribe from this group, send email to datamapper+unsubscr...@googlegroups.com. For more options, visit this group at http://groups.google.com/group/datamapper?hl=en.
Re: [DataMapper] get previous/next item in database
On 22 January 2013 12:04, Alex wrote:
> Thanks Ben. I do store timestamps in the table. Would you suggest I should
> check for older/newer timestamps inside this loop?
>
> #defines if a post of a user exists in db
>> def post_in_db
>> posts_of_user.each do |post|
>> if post.slug == params[:post_slug]
>> @post_slug ||= post.slug
>> @post_title ||= post.title
>> @post_body ||= post.body
>> @post_date ||= post.created_on
>> end
>> end
>> if @post_body == nil
>> redirect ('/' + params[:nickname])
>> end
>> end
>
>
> or I should store the @post_date and create a new helper with a new loop
> to find the immediate older/newer timestamp before/after the @post_date?
> I’m thinking in terms of performance the first method would be better.
>
> I'd just do a check for created_on < current for previous and created_on >
current for next and just call `first` with the predicate.
For example:
class Post
def prev
first(:created_at.lt => self.created_at)
end
def next
first(:created_at.gt => self.created_at)
end
#...
end
Note: This is gmail code and unchecked/tested :)
Cheers,
Ben
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Re: [DataMapper] get previous/next item in database
@Kristian Thanks, I haven’t tried it yet, but how does that get the next id? With the :id.gt ? How about the previous id? On Tuesday, January 22, 2013 1:13:51 PM UTC+2, kristian wrote: > > what about doing something like this : > > current_id = Audit.first.id > next = Audit.first( :id.gt => current_id ) > > - Kristian > -- You received this message because you are subscribed to the Google Groups "DataMapper" group. To view this discussion on the web visit https://groups.google.com/d/msg/datamapper/-/bEe_NnzF3MAJ. To post to this group, send email to datamapper@googlegroups.com. To unsubscribe from this group, send email to datamapper+unsubscr...@googlegroups.com. For more options, visit this group at http://groups.google.com/group/datamapper?hl=en.
Re: [DataMapper] get previous/next item in database
Thanks Ben. I do store timestamps in the table. Would you suggest I should
check for older/newer timestamps inside this loop?
#defines if a post of a user exists in db
> def post_in_db
> posts_of_user.each do |post|
> if post.slug == params[:post_slug]
> @post_slug ||= post.slug
> @post_title ||= post.title
> @post_body ||= post.body
> @post_date ||= post.created_on
> end
> end
> if @post_body == nil
> redirect ('/' + params[:nickname])
> end
> end
or I should store the @post_date and create a new helper with a new loop to
find the immediate older/newer timestamp before/after the @post_date? I’m
thinking in terms of performance the first method would be better.
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Re: [DataMapper] get previous/next item in database
what about doing something like this : current_id = Audit.first.id next = Audit.first( :id.gt => current_id ) - Kristian -- You received this message because you are subscribed to the Google Groups "DataMapper" group. To post to this group, send email to datamapper@googlegroups.com. To unsubscribe from this group, send email to datamapper+unsubscr...@googlegroups.com. For more options, visit this group at http://groups.google.com/group/datamapper?hl=en.
Re: [DataMapper] get previous/next item in database
On 22 January 2013 10:44, Alex wrote: > Hi, > I’m trying to get the previous and next item (articles) from a database > with Datamapper. I thought of doing it with the serial identifier > > property :id, Serial > > > and increment/decrease this number to find the previous/next posts of that > particular article, but it doesn’t work. Because the serial is incremented > fine for new articles (1,2,3,4,5), but if you delete say id: #3, then the > next article of #2 will be #4, not #3. > > Do you know if there is an easier/more correct way to do it with > Datamapper? > Hey Alex, Sounds like you're missing a concept in your application. Perhaps you should add some kind of ordering/page column to your table if you need to be explicit about ordering? This way you could rearrange the ordering if necessary, ensure uniqueness for pages/ordering and other goodness. Alternatively, if you're storing created_at timestamps on your tables you could use this as a surrogate for ordering. Cheers, Ben -- You received this message because you are subscribed to the Google Groups "DataMapper" group. To post to this group, send email to datamapper@googlegroups.com. To unsubscribe from this group, send email to datamapper+unsubscr...@googlegroups.com. For more options, visit this group at http://groups.google.com/group/datamapper?hl=en.
[DataMapper] get previous/next item in database
Hi, I’m trying to get the previous and next item (articles) from a database with Datamapper. I thought of doing it with the serial identifier property :id, Serial and increment/decrease this number to find the previous/next posts of that particular article, but it doesn’t work. Because the serial is incremented fine for new articles (1,2,3,4,5), but if you delete say id: #3, then the next article of #2 will be #4, not #3. Do you know if there is an easier/more correct way to do it with Datamapper? -- You received this message because you are subscribed to the Google Groups "DataMapper" group. To view this discussion on the web visit https://groups.google.com/d/msg/datamapper/-/DcHhm81m4OwJ. To post to this group, send email to datamapper@googlegroups.com. To unsubscribe from this group, send email to datamapper+unsubscr...@googlegroups.com. For more options, visit this group at http://groups.google.com/group/datamapper?hl=en.
