I have some trouble with mongoid:
test "Test candidate" do
User.create(:id => 1, :sex => User::Male, :country => 1, :city => 1)
User.create(:id => 2, :sex => User::Female, :country => 1, :city => 1)
User.create(:id => 3, :sex => User::Female, :country => 1, :city => 1)
user = User.not_in(:id => [2]).second
assert_not_equal(user.id, 2)
end
Test failed. I've tried to use where(:id => {'$nid' => [2]}), but it have same effect.
What is wrong? How to use "not in" condition with mongoid?
PS, "second" is ok, with "first" test passed, because id=1
Try this query:
user = User.not_in(:_id => [2]).second
In MongoDB primary key has name _id. Mongoid tries to be friendly and partially hides this fact from the developer by aliasing it to id in the object model. But when you do queries, it cannot tell if you want primary key _id or some completely ordinary field id.
user = User.where(:id.nin => [2,3,4,5])
This is as per mongoid official doc : http://mongoid.org/en/origin/docs/selection.html
Related
I'm successfully following some of the commands listed here and applying them to my own tables.
How do I turn the output into actual records/data ? Presently it's returning some output which I can assign to a variable, but I do not understand this output at all.. it doesn't look like an array or hash (but perhaps it is), and I do not understand how to access its contents (I want to use the output in a rails view, but at the least would like to access the table records in the console where I'm executing the Arel code)
For example, say I have two tables; User and Product as follows:
User = [{:id => 1, :name => "Joe", :email => "joe#gmail.com"}, {:id => 2, :name => "Jane", :email => "jane#gmail.com"}]
Product = [{:product_name => "Car Tire", :brand => "BMW", :last_edited_by => 1}, {:product_name => "Paint Brush", :brand => "Dulux", :last_edited_by => nil}, {:product_name => "Dog Biscuits", :brand => "Bowow Snacks", :last_edited_by => 2}, {:product_name => "Game", :brand => "Westwood", :last_edited_by => 1}]
Suppose I want to join the two tables User.id = Product.last_edited_by
In SQL it would be as simple as:
SELECT *
FROM User
JOIN Product
WHERE users.id = products.last_edited_by
Now if I plug this into scuttle.io to convert to Arel, it gives:
User.select(Arel.star).where(
User.arel_table[:id].eq(Product.arel_table[:last_edited_by])
).joins(
User.arel_table.join(Product.arel_table).on(null).join_sources
)
But trying this returns: ArgumentError: wrong number of arguments (given 1, expected 0)
Attempting to emulate advice given here, I come up with another approach:
users.project(Arel.star).join(User).on(Product[:last_edited_by].eq(User[:id]))
But this returns: NoMethodError: undefined method `project' for Array..
A final point, if I run
users = Arel::Table.new(User)
output = users.project(users[:id].as("id"), users[:id].count.as("count")).group("id")
I get some output which looks almost meaningful, but I don't know how to return that into something I can make sense of, and I wouldn't know how to use it if I provided it to a rails view
I'm using a rake task to populate my database with some initial data. I want to create a bunch of entries in a table, with the first few IDs, so they're always present, and always have those ids. I don't mind if in a dev environment, someone adds/deletes/modifies records, but I always want the first 5 ids to have values. Here's a simplified version of my lib/tasks/bootstrap.rb file:
namespace :bootstrap do
desc "Create the default problem types"
task :default_problem_types => :environment do
ProblemType.create( :id => 1, :name => 'Wrong location', :description => 'blah' )
ProblemType.create( :id => 2, :name => 'Wrong name', :description => 'blah' )
ProblemType.create( :id => 3, :name => 'Wrong details', :description => 'blah' )
ProblemType.create( :id => 4, :name => 'Duplicate', :description => 'blah' )
ProblemType.create( :id => 5, :name => 'No longer exists', :description => 'blah' )
end
desc "Run all bootstrapping tasks"
task :all => [:default_problem_types]
end
This works fine on an empty database. It creates 5 new entries in the problem_types table:
1 - Wrong Location
2 - Wrong name
3 - Wrong details
4 - Duplicate
5 - No longer exists
The problem is that if I run it a second time, it creates 5 new records, with IDs 6, 7, 8, 9, 10. That's despite the fact that I provided ids to the create() call that already exist. I'm expecting those calls to fail, because if I try to do the following SQL:
insert into problem_types (id, name, description) values (1, 'foo', 'bar');
... it fails:
ERROR 1062 (23000): Duplicate entry '1' for key 'PRIMARY'
How do I get the create() method to fail if the ID already exists?
Thanks.
Use a dynamic find_or_create_by or find_or_initialize_by method. You can read more about these in the Rails guides for the Active Record query interface. They allows you to write something like this for each ProblemType without creating duplicates by name:
problem_type = ProblemType.find_or_initialize_by_name('Wrong location')
problem_type.description = "blah"
problem_type.save
I agree with #benchwarmer; it's best to avoid managing the primary key yourself. If you must have a numerical identifier that some semantic value, try adding a separate column and set that value accordingly.
Rule of thumb: You dont assign ID on your own. Let database do its work. If you want your problem names to be unique then you can add validates_uniqueness_of :name into model file and the records won't be created if the same name exists
This is just a simple question. I was trying to create a new object in Rails by passing in parameters to the constructor. However, when I execute the code, I get
SQLite3::SQLException: no such column: awards.user_id: SELECT "awards".* FROM "awards" WHERE "awards"."user_id" = 1
which means the object isn't being constructed properly. Should I be using create instead of new? That isn't working either.
def refresh_awards(user)
new_awards = []
if (user.karma < 40 ) #test award
a = Award.new(:name => "Nobody Award", :description => "From Jonathan", :category => "Community", :value => 1337, :level => 0, :handle => "nobody_award")
user.awards.append(a)
new_awards.append(a)
end
new_awards.each do |a|
flash[:notice] = "You received the " + a.name + "!"
end
end
Have you add has_many :awards to the User model? Have you added belongs_to :user to the Award model? Have you added the column user_id to the Award model (using a migration)? You'll need to do these three things to be able to use the user.awards method you're using. Read the Rails Guide on Associations for more detail.
Also, append isn't a Ruby method - the closest method would be <<. You would use it like this:
a = Award.new(:name => "Nobody Award", :description => "From Jonathan", :category => "Community", :value => 1337, :level => 0, :handle => "nobody_award")
user.awards << a
But you could neaten this into one line of code using the create method:
a = user.awards.create(:name => "Nobody Award", :description => "From Jonathan", :category => "Community", :value => 1337, :level => 0, :handle => "nobody_award")
EDIT: To create the user_id column in the Award model, run the following code from terminal (while in your app's directory):
rails generate migration AddUserIdToAward user_id:integer
rake db:migrate
I have a join table, which have 3 parameters. I want to update it, using a where-clause, something like this: (which obviously is not correct)
Grid.update(:page_id => #page_id,:thing_id => #thing_id,:number => #number ).where(:page_id => #page_id, :number => #number ).first
I need to find the record with mathing page_id and number, and then update the thing_id.
Thanks!
Jakob
Grid.where(:page_id => #page_id, :number => #number).first.
update_attributes(:page_id => ...,: thing_id => ..., :number => ...)
I've got a Person model, who has_many roles, and roles, in turn, belong_to an application. I'd like to query all the roles a person has for a given application. So far I've got:
p = Person.includes(:roles => [:application]).where(:loginid => 'their_loginid', :roles => {:application_id => 1})
Which works, but it's querying based on Person.roles.application_id; instead, I'd like to query based on Person.roles.application.api_key (another property of an application).
I tried:
p = Person.includes(:roles => [:application]).where(:loginid => 'their_loginid', :roles => {:application => {:api_key => 'the_api_key'}})
but I receive the error that:
no such column: application.api_key
leading me to think my usage of ActiveRecord isn't joining the tables together correctly.
Any ideas?
Try this:
p = Person.includes(:roles => [:application]).where(:loginid => 'their_loginid', :role_id => Application.find_by_api_key('api_key').role_ids)
try this
p = Person.joins.includes(:roles => [:application]).where(:loginid => 'their_loginid', :roles => {:application => {:api_key => 'the_api_key'}})
In my case it woks.