I come across a small issue in my app. I'm currently using geokit to find objects near a given location, and I use the sort_by_distance_from on the found set.
See below:
#find = Item.find(:all, :origin =>[self.geocode.lat.to_f,self.geocode.lng.to_f], :within=>50, :include=>[:programs], :conditions=>["programs.name = ?", self.name])
#find.sort_by_distance_from([self.geocode.lat.to_f,self.geocode.lng.to_f]
Is there any way with geokit to paginate form the DB when sorting by distance?
AKA, not calling the full found set?
The distance column isn't working anymore:
"In the current version of geokit-rails, it is not possible to add a where clause using the distance column. I've tried many different ways to do this and didn't get it working."
It behaves the same way for where and order clauses.
One would expect to build a query like this :
scoped = Location.geo_scope(:origin => #somewhere)
scoped = scoped.where('distance <= 5')
results = scoped.all
This is not possible right now, it must be done in a single step like this:
scoped = Location.within(5, :origin => #somewhere)
results = scoped.all
github.com/geokit/geokit-rails
My approach to solve this, would use the :offset and :limit parameters for the find()
also, there is a distance field for geokit models, :order=>'distance asc'
eg.
page = 0 unless params[:page]
items_per_page = 20
offset = page * items_per_page
#find = Item.find(:all, :origin =>[self.geocode.lat.to_f,self.geocode.lng.to_f], :within=>50, :include=>[:programs], :conditions=>["programs.name = ?", self.name], :order => 'distance asc', :limit => items_per_page, :offset => page)
Related
I have a query of pictures like this
pictures = Picture.near([latitude, longitude], 6.8).where("created_at >= :time",{:time => time })
and I took out the tags which is associated with this model (every picture has_many :tags) like so
#tags = Tag.find(:all, :conditions => ["picture_id in (?)",pictures.collect(&:id)])
I used a query to pull out an attribute of each tag
#tags.map(&:tagcontent)
What I need to do is limit the results of the tags that come out. so I replaced
#tags = Tag.find(:all, :conditions => ["picture_id in (?)",pictures.collect(&:id)])
with this
numoftags = 6
tags = Tag.limit(numoftags).find(:all, :conditions => ["picture_id in (?)",pictures.collect(&:id)])
but this only yields 4 tags, when I know there is least 6 that can be pulled out. How should I modify this function.
In Rails 3.X you can do something like this (using Arel)
numoftags = 6
#tags = Tag.where(["picture_id in (?)",pictures.collect(&:id)]).limit(nooftags)
After quite a bit of searching, I'm still a bit lost. There are a few other similar questions out there that deal with paginating multiple models, but they are either unanswered or they pagainate each model separately.
I need to paginate all records of an Account at once.
class Account
:has_many :emails
:has_many :tasks
:has_many :notes
end
So, I'd like to find the 30 most recent "things" no matter what they are. Is this even possible with the current pagination solutions out there?
Like using some combination of eager loading and Kaminari or will_paginate?
Or, should I first set up a polymorphic join of all these things, called Items. Then paginate the most recent 30 items, then do a lookup of the associated records of those items.
And if so, I'm not really sure what that code should look like. Any suggestions?
Which way is better? (or even possible)
Rails 3.1, Ruby 1.9.2, app not in production.
with will_paginate :
#records = #do your work and fetch array of records you want to paginate ( various types )
then do the following :
current_page = params[:page] || 1
per_page = 10
#records = WillPaginate::Collection.create(current_page, per_page, records.size) do |pager|
pager.replace(#records)
end
then in your view :
<%=will_paginate #records%>
Good question... I'm not sure of a "good" solution, but you could do a hacky one in ruby:
You'd need to first fetch out the 30 latest of each type of "thing", and put them into an array, indexed by created_at, then sort that array by created_at and take the top 30.
A totally non-refactored start might be something like:
emails = Account.emails.all(:limit => 30, :order => :created_at)
tasks = Account.tasks.all(:limit => 30, :order => :created_at)
notes = Account.notes.all(:limit => 30, :order => :created_at)
thing_array = (emails + tasks + notes).map {|thing| [thing.created_at, thing] }
# sort by the first item of each array (== the date)
thing_array_sorted = thing_array.sort_by {|a,b| a[0] <=> b[0] }
# then just grab the top thirty
things_to_show = thing_array_sorted.slice(0,30)
Note: not tested, could be full of bugs... ;)
emails = account.emails
tasks = account.tasks
notes = account.notes
#records = [emails + tasks + notes].flatten.sort_by(&:updated_at).reverse
#records = WillPaginate::Collection.create(params[:page] || 1, 30, #records.size) do |pager|
pager.replace(#records)
end
Thats it... :)
Rails 2.3.5
I've looked at a number of other questions relating to building conditions dynamically for an ActiveRecord find.
I'm aware there are some great gems out there like search logic and that this is better in Rails3. However, I'm using geokit for geospacial search and I'm trying to build just a standard conditions set that will allow me to combine a slew of different filters.
I have 12 different filters that I'm trying to combine dynamically for an advanced search. I need to be able to mix equality, greater than, less than, in (?) and IS NULLs conditions.
Here's an example of what I'm trying to get working:
conditions = []
conditions << ["sites.site_type in (?)", params[:site_categories]] if params[:site_categories]
conditions << [<< ["sites.operational_status = ?", 'operational'] if params[:oponly] == 1
condition_set = [conditions.map{|c| c[0] }.join(" AND "), *conditions.map{|c| c[1..-1] }.flatten]
#sites = Site.find :all,
:origin => [lat,lng],
:units => distance_unit,
:limit => limit,
:within => range,
:include => [:chargers, :site_reports, :networks],
:conditions => condition_set,
:order => 'distance asc'
I seem to be able to get this working fine when there are only single variables for the conditions expression but when I have something that is a (?) and has an array of values I'm getting an error for the wrong number of bind conditions. The way I'm joining and flattening the conditions (based on the answer from Combine arrays of conditions in Rails) seems not to handle an array properly and I don't understand the flattening logic enough to track down the issue.
So let's say I have 3 values in params[:site_categories] I'll the above code leaves me with the following:
Conditions is
[["sites.operational_status = ?", "operational"], ["sites.site_type in (?)", ["shopping", "food", "lodging"]]]
The flattened attempt is:
["sites.operational_status = ? AND sites.site_type in (?)", ["operational"], [["shopping", "food", "lodging"]]]
Which gives me:
wrong number of bind variables (4 for 2)
I'm going to step back and work on converting all of this to named scopes but I'd really like to understand how to get this working this way.
Rails 4
users = User.all
users = User.where(id: params[id]) if params[id].present?
users = User.where(state: states) if states.present?
users.each do |u|
puts u.name
end
Old answer
Monkey patch the Array class. Create a file called monkey_patch.rb in config/initializers directory.
class Array
def where(*args)
sql = args.first
unless (sql.is_a?(String) and sql.present?)
return self
end
self[0] = self.first.present? ? " #{self.first} AND #{sql} " : sql
self.concat(args[1..-1])
end
end
Now you can do this:
cond = []
cond.where("id = ?", params[id]) if params[id].present?
cond.where("state IN (?)", states) unless states.empty?
User.all(:conditions => cond)
I have a form which is used to filter queries. Some of the form attributes are optional; I'm just wondering how to append them as activerecord conditions if (and only if) they have a set value?
There's a fair few of them, so I'd rather not make a separate query for each pattern of potential values. Any suggestions?
To give a specific example:
people = People.paginate(
:all,
:include => [:people_postcodes, :people_specialties, :people_states],
:conditions => ["people_specialties.people_type_id = %s AND (people_postcodes.postcode_id = %s OR people_states.state_id = %s)" % [self.people_type_id, postcodeid.id, stateid]],
:page => page,
:per_page => 16
)
How would I best go about creating an extra condition (say 'nationality') only if the optional 'nationality' attribute is populated?
First off, your conditions are a little insecure. You're doing basic ruby text substitution, which will let site users inject whatever malicious sql they want. Instead, format it like this:
people = People.paginate(
:all,
:include => [:people_postcodes, :people_specialties, :people_states],
:conditions => ["people_specialties.people_type_id = ? AND (people_postcodes.postcode_id = ? OR people_states.state_id = ?)", self.people_type_id, postcodeid.id, stateid],
:page => page,
:per_page => 16
)
To answer your question, there's no natural way to tack on another condition in Rails 2.x. I would do this:
conditions = ["people_specialties.people_type_id = ? AND (people_postcodes.postcode_id = ? OR people_states.state_id = ?)", self.people_type_id, postcodeid.id, stateid]
if params[:nationality]
conditions.first += " and nationality = ?"
conditions.push params[:nationality]
end
people = People.paginate(
:all,
:include => [:people_postcodes, :people_specialties, :people_states],
:conditions => conditions,
:page => page,
:per_page => 16
)
In the example above, I'm assuming nationality is passed in as a parameter, but adjust as needed. I create the original conditions array, then append the first element (the actual condition string) and add one more element to the end of the array: the nationality value.
I hope this helps!
How do I get a random record when using :group?
#paintings = Painting.all(:group => "user_id", :order => "created_at DESC")
This gives me the latest painting for each user. Now I would like to select a random painting from each user instead of the latest. The order of the paintings should still be the same, so that the user that have been the most active will get his/her random painting displayed first.
painting150 (user1)
painting200 (user2)
painting231 (user3)
Is this possible?
Best regards.
Asbjørn Morell.
This answer is specific to Rails, but since you are using ActiveRecord, I am assuming it should be fine.
unique_paintings = []
#paintings.group_by(&:user_id).each do |user_id, paintings|
unique_paintings << paintings[rand(paintings.size-1)]
end
unique_paintings.sort_by(&:created_at)
The group_by most certainly messes up the created_at sort you did in the query, so I did a sort_by as the last step. You might want to get rid of it in the query since you'll have to do it anyway here.
#painting = #paintings[rand(#paintings.size-1)]
(or paintings.count, dont know the right method yet)
Assuming you have MySQL, you can try:
#paintings = Painting.all(:group => "user_id", :order => "RAND()")
you could do something like this but it will suffer as your number of records grow
#paintings = Painting.find(:all, :order => 'RAND()').map{ |i| i.user_id }.uniq