Trying to get a count of Driver's cars when manual transmission = true. (Driver has_many cars; Car belongs_to driver, etc.)
My current code:
<% #driver = Driver.find(1) %>
<% driver.cars.where("Car.manual = true").count %>
Returns this error:
PG::UndefinedTable: ERROR: missing FROM-clause entry for table "car"
LINE 1: ...ars" WHERE "cars"."driver_id" = $1 AND (Car.m...
^
: SELECT COUNT(*) FROM "cars" WHERE "cars"."driver_id" = $1 AND (Car.manual= true)
When I remove the ".count", it does seem to find a relationship, because it prints:
#<Car::ActiveRecord_AssociationRelation:0x007fea6ddf4c88>
I also tried
<%= #driver.cars.where(manual = true).count %>
But that returns a count of all the driver's cars.
I suspect the problem is with my "manual = true" syntax, but I'm fairly new to writing queries so I'm probably missing something stunningly obvious. If anyone can help me figure out where I'm going wrong, I'd appreciate it. (Or, of course, if there's a better way to do this.)
The Driver class should declare the relationship:
class Driver
has_many :cars
# other things
end
And then, you have to pass a hash to the where conditions:
<%= #driver.cars.where(manual => true).count %>
or using the new ruby hash syntax:
<%= #driver.cars.where(manual: true).count %>
You can always debug the query being sent to the database with
<%= #driver.cars.where(manual: true).to_sql %>
Related
I've been trying for a while to find the best way of querying for the desired result, but I always end up failing at some poing in the query.
Simplified database structure:
User:
id (integer)
first_name (string)
last_name (string)
CourseType:
title (string)
slug (string)
Course:
belongs_to :user
belongs_to :course_type
week (integer)
sold (float)
My controller is calling a scope:
#users = User.sales_results(week)
And here's the scope in my model:
scope :sales_results, lambda { |week|
joins(:courses => [:course_type])
.select("
users.id, users.first_name, users.last_name,
SUM(courses.sold) as total_sold,
COUNT(courses) as num_classes
")
.where("courses.week = ?", week)
.group('users.id')
}
This works fine, and I can use it in my template to show the total amount sold. Although I also want to show a second column where the value sold for some specific types of courses are summed up in. Something like this:
<% #users.each do |user| %>
<%= user.total_sold %>
<%= user.total_sold.where("course_types.slug IN ('H', 'S')") # not possible, but similar to what I desire %>
<% end %>
Update
I ended up adding another scope
scope :sales_results_for_types, lambda { |week, types|
sales_results(week).except(:group).where("course_types.slug IN (?)", types)
.group('users.id')
}
Then calling both scopes in my controller
#users = User.sales_results(...)
#users_filtered = User.sales_results_for_types(...)
Lastly iterating both results at the same time
<% #users.zip(#users_filtered).each do |user, filtered| %>
<%= filtered.total_sold %>
<%= user.total_sold %>
Until I figure out something better. Thanks guys for leading me on the right track.
If you are ok with having another query, you can use this
user.joins(courses: :course_type).sum(:sold, group: 'course_types.slug')
which will give you a hash where the keys are the slugs, and the values are the sums.
This seems like it should be a common problem but I'm having trouble finding an answer. Basically I want to have a form with 10 or so checkboxes which I'm creating with check_box_tag. When the form is submitted I want to generate a query that return all records that match ANY of the checked selections. So, the number of checked selections will vary.
So, for example, if I have
class Book < ActiveRecord::Base
belongs_to :author
end
I want to generate something like
Book.where("author_id = ? or author_id = ?", params[authors[0]], params[authors[1]]) if there are two boxes checked, etc.
Thanks for any insight.
Will this work for you?
Book.where(author_id: [array_of_author_ids])
You need to collect author_ids from params first
I recently had to do something similar, this is how I achieved this. It's pretty clever (at least I think so. :))
I created a query model that serializes the query column (text field) in JSON. I use a form to get the query data from the user with selection fields.
class BookQuery < ActiveRecord::Base
has_many :books
# loop through each foreign key of the Book table and create a hash with empty selection
def self.empty_query
q = {}
Book.column_names.each do |column_name|
next unless column_name.ends_with?("_id")
q.merge column_name => []
end
end
end
I'm using Author as an example below:
<%= form_for #book_query do |f| %>
<% for author in Author.all %>
<%= check_box_tag "book_query[query][author_ids][]", author.id, false%>
<%= author.name %>
<% end %>
<%= f.submit "Save Query" %>
<% end %>
When this form is submitted you ended up with parameters like this:
When the form is submitted it generates this parameter:
Parameters: {"utf8"=>"✓", "authenticity_token"=>"XXXXXXXXXXX", "book_query"=>{"query"=>{"author_ids"=>["2", "3"]}}, "commit"=>"Save Query"}
Now in the BookQuery controller's create action you can just do what create function always does:
def create
#book_query = BookQuery.build(params[:book_query])
if #book_query.save
flash[:success] = "Book query successfully saved."
redirect_to ...
else
flash[:error] = "Failed to save book query."
render :new
end
end
But by default rails serializes the data in hash type:
1.9.3p194 :015 > pp BookQuery.find(9).query
BookQuery Load (0.7ms) SELECT "book_queries".* FROM "book_queries" WHERE "book_queries"."id" = $1 LIMIT 1 [["id", 9]]
"--- !ruby/hash:ActiveSupport::HashWithIndifferentAccess\nauthor_ids:\n- '2'\n- '3'\n"
=> "--- !ruby/hash:ActiveSupport::HashWithIndifferentAccess\nauthor_ids:\n- '2'\n- '3'\n"
In BookQuery model, add the following:
serialize :query, JSON
But rail would change the IDs to string:
1.9.3p194 :018 > query = JSON.parse(BookQuery.find(10).query)
BookQuery Load (0.5ms) SELECT "book_queries".* FROM "book_queries" WHERE "book_queries"."id" = $1 LIMIT 1 [["id", 10]]
=> {"author_ids"=>["2", "3"]}
1.9.3p194 :019 > query["author_ids"]
=> ["2", "3"]
What I did then is override the attribute accessors in BookQuery model:
The below has to be done because the hash returns strings, not ids in integer.
def query=(query)
query.each_pair do |k, v|
if query[k].first.present?
query[k].map!(&:to_i)
else
query.except!(k)
end
end
write_attribute(:query, query)
end
# just want to avoid getting nil query's
def query
read_attribute(:query) || {}
end
To find book with this query, you can simply add this function to your Book model:
def self.find_by_book_query(book_query, options = {})
options[:conditions] = book_query.query
find(:all, options)
end
Now you get a customizable query string based on the model definition Book and everything works like the Rails way. :)
I have in my controller this:
#itemsok = Search.where("first_item_id = ?", params["3"])
This is sopposed to be a query in the search table of the database asking for all the searches that have a first_item_id = 3 ...
Question 1 .- The syntax is I found it in http://guides.rubyonrails.org/active_record_querying.html but im not sure if im using it right?
Ok the question 2 is, I have this on the controller, is it ok to have querys in the controller?
In the view im printing the variable <%= #itemsok %> and all I get is a
ActiveRecord::Relation:0x007fd3d3e894d8
Any suggestions?
Thanks in advance.
ActiveRecord 3 lets you chain relations together so you can do something like this:
#itemsok = Search.where("first_item_id = ?", params["3"]).where("foo = ?", "bar")
The where() function returns an ActiveRecord::Relation. Generally this isn't a problem, since if you use the object it'll automatically run the query and return the results on the object so you'll get the database objects. AR doesn't run the query until it's actually needed.
Where will return a list of items (Array), so if you're just debugging, change your view to this:
<%= debug #itemsok.to_a %>
You seem to be constructing the query wrong way.
If you want to search for records with first_item_id = 3, you should do:
Search.where("first_item_id = ?", 3)
This will return an array of matching records, something you can't easily print with <%= #itemsok %>. You should iterate over the elements and print each one:
<% #itemsok.each do |item| %>
<%= item.name %>
<% end %>
I'd also suggest defining to_s method for the objects you want to print.
class Search
def to_s
name
end
end
Then you can simply print the object and to_s method will be automatically called for you:
<% #itemsok.each do |item| %>
<%= item %>
<% end %>
The right way to do is to define a namedscope in the model and then use it in the controller.
Something similar to this :
class Search < ActiveRecord::Base
named_scope:item_ok,lambda {|*args|{:conditions=>["item_id >= ?", args.first]}}
end
and then call the namedscope from the controller like this :
#itemsok = Search.item_ok(params[:value])
I am working the acts-as-taggable-on gem and have a question about how to filter down search results based on tags users select. Here's an abridged look at my controller:
class PhotosController < ApplicationController
def index
#photos = Photo.where(["created_at > ? AND is_approved = ?", 1.months.ago, true])
#tags = ["Animals", "Architecture", "Cars", "Flowers", "Food/Drink", "General", "Landscape", "Mountains", "Nature"]
end
def search_by_tag(tag)
#photos = Photo.where('tagged_with LIKE ?', tag)
end
end
Photos/index
<% #tags.each do |tag| %>
<%= link_to tag, {:search_by_tag => tag}, :class => "tag" %>
<% end %>
This lists out all of the tags from the hash #tags defined in index, but clicking them doesn't actually filter anything down. Here's a look at what clicking one of those links produces in the log:
Started GET "/photos?search_by_tag=Animals" for 127.0.0.1 at Sun Oct 09 17:11:09 -0400 2011
Processing by PhotosController#index as HTML
Parameters: {"search_by_tag"=>"Animals"}
SQL (0.5ms) SELECT name FROM sqlite_master WHERE type = 'table' AND NOT name = 'sqlite_sequence'
The result I want is for the page to display only Photos that are tagged_with whichever tag was clicked on. I can't quite figure out how to accomplish this.
(Side-question: I can't seem to find a way to list out all of the tags from the tags table that acts-as-taggable-on generated. Doing something like Photo.tagged_with or Photo.tags doesn't work. I am able to see the "tags" table the gem created, and the entries inside of it; I'm just not really clear how to handle that using this gem)
Any thoughts greatly appreciated.
UPDATE
I've updated my code and am a bit closer.
class PhotosController < ApplicationController
def search_by_tag
#photos = Photo.tagged_with(params[:tag_name])
end
photos/index
<% Photo.tag_counts_on(:tags).map(&:name).each do |tag| %>
<%= link_to tag, {:action => 'search_by_tag', :tag_name => tag}, :class => "tag" %>
<% end %>
I believe this is closer, but still working through this...
You have a number of errors in your code:
Your link_to call is actually calling the index action.
Your search_by_tag method is expecting an argument, where it should be using the params hash to access the parameters passed to it in the web request.
tagged_with is a class method added by acts_as_taggable_on, not a field in your table - therefore you can't use it in the where method like you have done.
Finally, to get all the tag names: Photo.tag_counts_on(:tags_or_whatever_you_tagged_on).map(&:name)
Take a look at the acts_as_taggable_on documentation and you'll see examples of how to use tag_counts_on and tagged_with.
As for the Rails things: http://guides.rubyonrails.org/ http://railsforzombies.org/ and/or http://railscasts.com/
I have a radio_button_tag in a form, which holds various values for a persons current availability:
Mike Donnall o Available o Out of office o Vacation
So originally you open the form, and select a value, this then sets the value in the Status table for that Person.
However, there's also functionality to re-open the form and update his present status, perhaps from Vacation to Available.
My question is, is there anyway at all that radio button :checked can be modified to accept a custom method, I have found something in a similar posting, but I want the value foe that radio button to be set to the value in the DB.
My code so far, a stab in the dark perhaps:
View:
<% #people.each do |p| %>
<% #statuses.each do |s| %>
<%= "#{p.name}" %>
<%= "#{s.status_name}" -%><%= radio_button_tag ['person', p.id], ['status',
s.id], checked?(p.id) %>
<% end %>
<% end %>
Helper:
def checked?(person)
#person = person
#status = Status.find_by_sql(['select status_id from statuses where person_id = ?, #person])
if #result
return true
end
As you can see Im a bit lost here, but I understand that the method should return the value of the checkbox that needs to be checked, but Im wondering because its a checked functionality, would it only be limited to being a true or false?
So for a persons.status.id check if its true or false.
It seems from your helper's SQL that you the following relationship setup between People and Statuses:
class Person < ActiveRecord::Base
has_one :status
end
class Status < ActiveRecord::Base
belongs_to :person
end
You can access one given person status like this:
person = Person.first
person_status = person.status
Using that knowledge, your desired view outcome becomes quite simple:
<% #people.each do |p| %>
<p><%= "#{p.name}" -%>
<% #statuses.each do |s| %>
<%= "#{s.status_name}" -%>
<%= radio_button_tag ['person', p.id],
['status', s.id],
(p.status == s) ? true : false %>
<% end %>
<% end %>
You can of course extract the logic to a helper, but that doesn't seem necessary.
On a personal note, this isn't the way I'd present the information to user, it' too heavy on information in one line. I suggest you put the person's name in a p tag, and use a ul tag for the statuses.