I want do query on model, and next depend on resaults do someting else
The problem:
exists = false
App.User.where(email: "example#domain.com").exists (error, exists) =>
console.log exists #=> true
console.log exists #=> false
Example why I want this:
class App.User extends Tower.Model
newUser: ->
exists = false
App.User.where(email: "some#email.com").exists (error, exists) =>
unless exists # here is always: exists = false
#.create
email: "some#email.com" # so user is created
I also tried something like this:
class App.User extends Tower.Model
newUser: ->
#.where(email: "some#email.com").exists (error, exists) =>
unless exists # statement works
#.create # but I can't create an user
email: "some#email.com"
App.User.create # also doesn't work
email: "some#email.com"
user = new App.User # this also fails
user.set "email", "some#email.com"
user.save()
Queries to the database are asynchronous, which means any code you need to run after the data comes back have to be inside the callback. So in your first example, that unless exists is actually going to run before the database query completes. I think if you indent it and the code that comes after it by two spaces, that will place it inside the callback and it will run as intended.
Try:
class App.User extends Tower.Model
newUser: ->
exists = false
App.User.where(email: "some#email.com").exists (error, exists) =>
unless exists
#.create
email: "some#email.com"
If the uniqueness validation was working correctly, you could get the same result more easily by just placing a uniqueness validation on your model. So in your model you would have something like:
class App.User extends Tower.Model
#field "email", type: "String"
#field "firstName", type: "String"
#field "lastName", type: "String"
#hasMany "posts"
#validates 'email', uniqueness: true
#timestamps()
Unfortunately, based on some recent experiments, there's a small bug in uniqueness causing it to fail. I posted the bug on tower's issues list and I'm also looking into it myself, so hopefully it will be working properly soon.
Hope this helps.
Edit: Thought I would mention, I'm not entirely sure why the second example fails, since it looks a lot like my suggestion, unless either I'm wrong or the context (the value of #) is changing because of using # in the database query instead of App.User.
Related
I'm stuck with a classic greatest-n-per-group problem, where a cat can have many kittens, but I'm usually just interested in the youngest.
I already do know how to build a scope and a has_one relation for the Cat.
My question: Is there a way to...
list all cats' names together with their youngest kittens' names...
while at the same time ordering them by their respective youngest kitten's name...
...using just a single SELECT under the hood?
What I got so far:
class Cat < ApplicationRecord
has_many :kittens
has_one :youngest_kitten, -> { merge(Kitten.youngest) }, foreign_key: :cat_id, class_name: :Kitten
scope :with_youngest_kittens, lambda {
joins(:kittens)
.joins(Kitten.younger_kittens_sql("cats.id"))
.where(younger_kittens: { id: nil })
}
end
class Kitten
belongs_to :cat
scope :youngest, lambda {
joins(Kitten.younger_kittens_sql("kittens.cat_id"))
.where(younger_kittens: { id: nil })
}
def self.younger_kittens_sql(cat_field_name)
%{
LEFT OUTER JOIN kittens AS younger_kittens
ON younger_kittens.cat_id = #{cat_field_name}
AND younger_kittens.created_at > kittens.created_at
}
end
end
When I run Cat.with_latest_kittens.order('kittens.name').map(&:name) everything looks fine: I get all the cats' names with just a single SELECT.
But when I run Cat.with_latest_kittens.order('kittens.name').map {|cat| cat.youngest_kitten.name}, I get the right result too, but a superfluous additional SELECT per cat is executed. Which is just logical, because the with_youngest_kittens doesn't know it should populate youngest_kitten. Is there a way to tell it or am I going about this all wrong?
I think adding an includes to your :with_youngest_kittens scope will fix the problem. Try changing the scope to
scope :with_youngest_kittens, lambda {
includes(:youngest_kitten)
.joins(:kittens)
.joins(Kitten.younger_kittens_sql("cats.id"))
.where(younger_kittens: { id: nil })
}
This should prevent Rails from making a separate database query for every kitten.
I found a solution that produces no extra SELECT, however it is quite ugly, so I'll actually go for localarrow's solution as it's more readable!
I thought I'd still post it for the sake of completeness (If someone needs the few ms extra performance):
First I add custom tailored select fields for each kitten column to the Cat.with_youngest_kitten scope:
scope :with_youngest_kittens, lambda {
kitten_columns = Kitten
.column_names
.map { |column_name| "kittens.#{column_name} AS `youngest_kittens.#{column_name}`" }
.join(', ')
joins(:kittens)
.joins(Kitten.latest_outer_join_sql("cats.id"))
.where(later_kittens: { id: nil })
.select("cats.*, #{kitten_columns}")
}
Then I override the has_one youngest_kitten relation with a method, that retrieves those custom selects and calls super if no data has been retrieved:
def youngest_kitten
return super if self[:'youngest_kittens.id'].nil?
kitten_hash = Hash[Kitten.column_names.collect { |column_name| [column_name, self[:"youngest_kittens.#{column_name}"]] }]
kitten_hash[:cat] = self
Kitten.new(kitten_hash)
end
I have a model, Message that belongs to the model User and the User model has an attribute name.
Message:
user_id
message_body
1
"hello world"
User:
user_id
name.
1
"johndoe"
The result I want is a complete list of all the messages and the respective user name that created each of those messages.
the api controller endpoint looks something like:
def index
#messages = Message.all
render json: { messages: #messages }
end
The issue is that when I return #messages it only contains the user_id that each message belongs to. What I really want is the user name
I could loop through every message and construct an entirely new object that looks something like:
#object = [
{
name: #messages[0].user.name,
message_body: #messages[0].body
},
{
name: #messages[1].user.name,
message_body: #messages[1].body
},
etc.
]
and then call render json: { messages: #object }
This would probably work fine, but it seems inefficient. Is there a better method for joining these tables for this result?
name
message body
"johndoe"
"hello world"
I was hoping the above example would be enough to get the answer I'm looking for. This is a simplified version of my architecture. In reality it's a bit more complicated:
LeagueChatMessage belongs_to LeagueChat
LeagueChatMessage belongs_to User
LeagueChat belongs_to League
League has_one LeagueChat
so this is really what the controller looks like
def index
#league = League.find_by(id: 1)
render json: { messages: #league.league_chat.league_chat_messages }
end
it works fine. It returns all the league chat messages for the league with the id: 1 but it returns the user_id for each message instead of the user name
Use following logic
#data = Message.includes(:user)
Now you can use like below
#data.each do |msg|
puts "Message #{msg.body}"
puts "User #{msg.user.name}"
end
I used puts for understanding but you can use this object in views as you want. And your approach leads to an n+1 query problem, so I used the includes, which helps remove the n+1 query. Try this and let me know if you have any queries.
For the sake of this question, let's say I have a very simple model:
class DystopianFuture::Human < ActiveRecord::Base
has_many :hobbies
validates :hobbies, :presence => {message: 'Please pick at least 1 Hobby!!'}
end
The problem is that when a human is updating their hobbies on a form and they don't pick any hobbies, there's no way for me to reflect this in the code without actually deleting all the associations.
So, say the action looks like this:
def update
hobbies = params[:hobbies]
human = Human.find(params[:id])
#ideally here I'd like to go
human.hobbies.clear
#but this updates the db immediately
if hobbies && hobbies.any?
human.hobbies.build(hobbies)
end
if human.save
#great
else
#crap
end
end
Notice the human.hobbies.clear line. I'd like to call this to make sure I'm only saving the new hobbies. It means I can also check to see if the user hasn't checked any hobbies on the form.
But I can't do that as it clears the db. I don't want to write anything to the database unless I know the model is valid.
What am I doing wrong here?
Initialy I also did this same way. Then found out one solution for this issue.
You need to do something like this
params[:heman][:hobby_ids]=[] if params[:human][:hobby_ids].nil?
Then check
if human.update_attributes(params[:human])
Hope you will get some idea...
EDIT:
Make hobbies params like this
hobbies = { hobbies_attributes: [
{ title: 'h1' },
{ title: 'h2' },
{ title: 'h3', _destroy: '1' } # existing hobby
]}
if Human.update_atttributes(hobbies) # use this condition
For this you need to declare accepts_nested_attributes_for :hobbies, allow_destroy: true in your Human model.
See more about this here http://api.rubyonrails.org/classes/ActiveRecord/NestedAttributes/ClassMethods.html
You can try https://github.com/ryanb/nested_form for this purpose..
I have an issue related to filtering data in Netzke Grid.
column :user_id do |c|
c.editor = {xtype: :combobox, editable: false, min_chars: 2}
end
It is mentioned in the doc that,
A hash that will override the automatic editor configuration. For example, for one-to-many association column you may set it to {min_chars: 1}, which will be passed to the combobox and make it query its remote data after entering 1 character (instead of default 4).
Seems {min_chars: 1} is not working as expected.
Please see example below for simple Customers grid and let me know if it works for you. Netzke way is to use __ (double underscore) to define one-to-many associations. This gives you combobox and all necessary data bindings. I tried different ways to make min_chars property work, but it all failed. Could be a bug. In the end, the only thing that worked is to do it from init_component method.
class Customers < Netzke::Basepack::Grid
def configure(c)
super
c.model = 'Customer'
c.columns = [
{ name: :name, header: 'Customer Name' },
{ id: :country__name, name: :country__name, header: 'Country' }
]
end
js_configure do |c|
c.init_component = <<-JS
function() {
this.callParent();
Ext.ComponentManager.get('country__name').editor.minChars = 2;
}
JS
end
end
I want to use FactoryGirl.attributes_for in controller testing, as in:
it "raise error creating a new PremiseGroup for this user" do
expect {
post :create, {:premise_group => FactoryGirl.attributes_for(:premise_group)}
}.to raise_error(CanCan::AccessDenied)
end
... but this doesn't work because #attributes_for omits the :user_id attribute. Here is the difference between #create and #attributes_for:
>> FactoryGirl.create(:premise_group)
=> #<PremiseGroup id: 3, name: "PremiseGroup_4", user_id: 6, is_visible: false, is_open: false)
>> FactoryGirl.attributes_for(:premise_group)
=> {:name=>"PremiseGroup_5", :is_visible=>false, :is_open=>false}
Note that the :user_id is absent from #attributes_for. Is this the expected behavior?
FWIW, my factories file includes definitions for :premise_group and for :user:
FactoryGirl.define do
...
factory :premise_group do
sequence(:name) {|n| "PremiseGroup_#{n}"}
user
is_visible false
is_open false
end
factory :user do
...
end
end
Short Answer:
By design, FactoryGirl's attribues_for intentionally omits things that would trigger a database transaction so tests will run fast. But you can can write a build_attributes method (below) to model all the attributes, if you're willing to take the time hit.
Original answer
Digging deep into the FactoryGirl documentation, e.g. this wiki page, you will find mentions that attributes_for ignores associations -- see update below. As a workaround, I've wrapped a helper method around FactoryGirl.build(...).attributes that strips id, created_at, and updated_at:
def build_attributes(*args)
FactoryGirl.build(*args).attributes.delete_if do |k, v|
["id", "created_at", "updated_at"].member?(k)
end
end
So now:
>> build_attributes(:premise_group)
=> {"name"=>"PremiseGroup_21", "user_id"=>29, "is_visible"=>false, "is_open"=>false}
... which is exactly what's expected.
update
Having absorbed the comments from the creators of FactoryGirl, I understand why attributes_for ignores associations: referencing an association generates a call to the db which can greatly slow down tests in some cases. But if you need associations, the build_attributes approach shown above should work.
I think this is a slight improvement over fearless_fool's answer, although it depends on your desired result.
Easiest to explain with an example. Say you have lat and long attributes in your model. On your form, you don't have lat and long fields, but rather lat degree, lat minute, lat second, etc. These later can converted to the decimal lat long form.
Say your factory is like so:
factory :something
lat_d 12
lat_m 32
..
long_d 23
long_m 23.2
end
fearless's build_attributes would return { lat: nil, long: nil}. While the build_attributes below will return { lat_d: 12, lat_m: 32..., lat: nil...}
def build_attributes
ba = FactoryGirl.build(*args).attributes.delete_if do |k, v|
["id", "created_at", "updated_at"].member?(k)
end
af = FactoryGirl.attributes_for(*args)
ba.symbolize_keys.merge(af)
end
To further elaborate on the given build_attributes solution, I modified it to only add the accessible associations:
def build_attributes(*args)
obj = FactoryGirl.build(*args)
associations = obj.class.reflect_on_all_associations(:belongs_to).map { |a| "#{a.name}_id" }
accessible = obj.class.accessible_attributes
accessible_associations = obj.attributes.delete_if do |k, v|
!associations.member?(k) or !accessible.include?(k)
end
FactoryGirl.attributes_for(*args).merge(accessible_associations.symbolize_keys)
end
Here is another way:
FactoryGirl.build(:car).attributes.except('id', 'created_at', 'updated_at').symbolize_keys
Limitations:
It does not generate attributes for HMT and HABTM associations (as these associations are stored in a join table, not an actual attribute).
Association strategy in the factory must be create, as in association :user, strategy: :create. This strategy can make your factory very slow if you don't use it wisely.
The accepted answer seems outdated as it did not work for me, after digging through the web & especially this Github issue, I present you:
A clean version for the most basic functionality for Rails 5+
This creates :belongs_to associations and adds their id (and type if :polymorphic) to the attributes. It also includes the code through FactoryBot::Syntax::Methods instead of an own module limited to controllers.
spec/support/factory_bot_macros.rb
module FactoryBot::Syntax::Methods
def nested_attributes_for(*args)
attributes = attributes_for(*args)
klass = args.first.to_s.camelize.constantize
klass.reflect_on_all_associations(:belongs_to).each do |r|
association = FactoryBot.create(r.class_name.underscore)
attributes["#{r.name}_id"] = association.id
attributes["#{r.name}_type"] = association.class.name if r.options[:polymorphic]
end
attributes
end
end
this is an adapted version of jamesst20 on the github issue - kudos to him 👏