I have a Lesson model that contains about 50 fields that all reference a Grade model. The grades model has a simple list 0-8 that is used as a lessons graded value.
Is there a way to avoid filling up my model with 50 lines of:
belongs_to :walking, :class => 'Grade'
belongs_to :running, :class => 'Grade'
belongs_to :crawling, :class => 'Grade'
...
postgres database
You could do this:
fields = %w[walking running crawling] # list all 50 of them here
fields.each { |field| belongs_to field.to_sym, :class => 'Grade' }
That will at least save you from having to write all the lines out, but you still need to list the names of the associations (walking, running, crawling, etc.) for it to work (as I've indicated above).
Related
I am building an eCommerce website using rails 5 and activeadmin gem to manage my dashboard. I have a product and a category model in a many to one relationship.
class Product < ApplicationRecord
before_destroy :not_referenced_by_any_line_item
belongs_to :category
has_many :line_items, dependent: :destroy
has_many :reviews, dependent: :destroy
def self.search(search)
all.where("lower(title) LIKE :search", search: "%#{search}%")
end
private
def not_referenced_by_any_line_item
unless line_items.empty?
errors.add(:base, "line items present")
throw :abort
end
end
end
class Category < ApplicationRecord
has_many :products, dependent: :destroy
def self.search(search)
all.where("lower(category_name) LIKE :search", search: "%#{search}%")
end
end
I then registered the models to the activeadmin dashboard as below
ActiveAdmin.register Product do
permit_params :title, :description, :availability,
:price, :photo_link, :category_id, :advert, :pictureOne,
:pictureTwo, :pictureThree
end
ActiveAdmin.register Category do
permit_params :category_name, :photos
end
I can now select a product category on the project form when creating a product but the problem is, instead of a category name or any other field to display on the project category form input field so that you know exactly which category you are selecting,an abject is being displayed making it difficult to know which category you are selecting. display of dropdown of product category input form field:
ActiveAdmin's default functionality is to look for a name field on a given model when deciding what to render as the record's identifier. If the model doesn't have a name field, ActiveAdmin doesn't how else to let you which record you're dealing with besides being able to show you a stringified mess of the location where that record is in memory (It's the same string you'd get if you did Category.first.to_s in the console).
To get the ActiveAdmin to recognize the name, you have to override the default edit form it creates for you so you can customize the select label.
You'll add all the fields you want to be editable to the form. When you get adding the input for the category, you specify that you want that field to be a select and you can customize the select's label, like so:
# app/admin/product.rb
ActiveAdmin.register Product do
permit_params :title, :description, :availability,
:price, :photo_link, :category_id, :advert, :pictureOne,
:pictureTwo, :pictureThree
form do |f|
f.inputs do
# Add a form input for the category
#
# This approach also allows you to specify which categories you
# allow to be selected, in the "collection" attribute.
#
# Inside the "map" call, you have the proc return an array with the first item
# in the array being the name of the category (the label for the select)
# and the second item being the category's ID (the select's value)
f.input :category_id, label: 'Category', as: :select, collection: Category.all.map{ |c| [c.category_name, c.id]}
# Then add other inputs
f.input :title
f.input :description
f.input :availability
# ...
# (Add f.input for the rest of your fields)
end
f.actions
end
end
You'll follow similar methods when you need to render the name a category in other places in ActiveAdmin.
If it's not too much trouble, you'll probably be better off renaming category_name on your Category model to just name. That way, you'll be fighting with ActiveAdmin a lot less and won't need to make customizations like this as much.
Summary:
I have a model with a few "belongs_to" associations and when I call Model.all (or another custom method if need be) I want to not only return all columns of Model, but also one column from each of the associated Models. Basically instead of just returning the ID's of the associated Models I want to get a more friendly attribute like "name".
Using Rails 3.2.x
Model Details:
I have five models, basically for data normalization.
class ActionItem < ActiveRecord::Base
belongs_to :action_item_status
belongs_to :prod_ops_acceptance
belongs_to :action_item_priority
belongs_to :incident_ticket
<truncated the rest>
end
class IncidentTicket < ActiveRecord::Base
attr_accessible :number
has_many :action_items
validates_presence_of :number
end
class ActionItemPriority < ActiveRecord::Base
attr_accessible :name
has_many :action_items
validates_presence_of :name
end
class ActionItemStatus < ActiveRecord::Base
attr_accessible :name
has_many :action_items
validates_presence_of :name
end
class ProdOpsAcceptance < ActiveRecord::Base
attr_accessible :name
has_many :action_items
validates_presence_of :name
end
Attempted Solutions:
I've tried many combinations of things including using ActionItem.includes and ActionItem.joins to no avail. The latest thing I tried is (trying only for the 'number' attribute of the IncidentTicket model to start with...)
ActionItem.all(
select: 'action_items.title, incident_tickets.number',
joins: 'INNER JOIN incident_tickets
ON action_items.incident_ticket_id = incident_tickets.id')
The above only returns the 'title' attribute from the ActionItem model and not the 'number' attribute from the IncidentTicket model despite the SQL looking correct. It seems like the SELECT on the joined table is completely ignored no matter what I try.
Obviously I am seriously missing something here or doing this completely wrong. I feel like there is some ActiveRecord magic that I'm missing out on that makes this trivial. Any help would be much appreciated! Please let me know if you need more details, I feel like this is kind of difficult to explain...
This ought to work for you:
action_items =
ActionItem.joins(:incident_ticket, :action_item_priority, ...)
.select(%[ action_items.title,
incident_tickets.number AS incident_ticket_number,
action_item_priorities.name AS action_item_priority_name,
... ]
)
.all
logger.info(action_items.first.incident_ticket_number)
What I ended up doing for now is creating a method that returns an array containing the results of ActionItem.all with the additional attributes I want injected in. This can probably be optimized, but I haven't spent any more time focusing on that just yet:
def self.all_with_extras
action_items_with_extras = []
action_items = ActionItem.all.to_json
JSON.parse(action_items).each do |ai|
extras = {
'incident_ticket_number' => IncidentTicket.find(ai['incident_ticket_id']).number,
'status' => ActionItemStatus.find(ai['action_item_status_id']).name,
'priority' => ActionItemPriority.find(ai['action_item_priority_id']).name,
'acceptance' => ProdOpsAcceptance.find(ai['prod_ops_acceptance_id']).name
}
with_extras = ai.merge(extras)
action_items_with_extras.append(with_extras)
end # each
action_items_with_extras
end # def
I have a collection of related models: A structure has_many residues and a residue has_many atoms. I've setup my ActiveAdmin using the belongs_to keyword, e.g.
ActiveAdmin.register Residue do
belongs_to :structure
end
I want to use ActiveAdmin as a way to filter down the entities in my database. For instance, on the Structures index page, I can filter my results on any of the column fields, let say I filter based on structure_name. I want to take this list of structures, and view all the related residues. Then, filter this list of residues, and view all the related atoms, etc.
From reading the ActiveAdmin documentation, it looks like I might be able to do something like this using the batch actions functionality (http://www.activeadmin.info/docs/9-batch-actions.html), but I can't seem to figure it out. Any pointers would be greatly appreciated.
What are the relations between all your models?
Did you try to add more filters like this in your Index page?
# Examples:
filter :structure_residue_name, :as => :string, :label => "Residue Name"
filter :structure_residue_atom_name, :as => :string, :label => "Atom Name"
I want to create an activity feed from recent article and comments in my rails app. They are two different types of activerecord (their table structures are different).
Ideally I would be able to create a mixed array of articles and comments and then show them in reverse chronological order.
So, I can figure out how to get an array of both articles and comments and then merge them together and sort by created_at, but I'm pretty sure that won't work as soon as I start using pagination as well.
Is there any way to create a scope like thing that will create a mixed array?
One of the other problems for me, is that it could be all articles and it could be all comments or some combination in between. So I can't just say I'll take the 15 last articles and the 15 last comments.
Any ideas on how to solve this?
When I've done this before I've managed it by having a denormalised UserActivity model or similar with a belongs_to polymorphic association to an ActivitySource - which can be any of the types of content that you want to display (posts, comments, up votes, likes, whatever...).
Then when any of the entities to be displayed are created, you have an Observer that fires and creates a row in the UserActivity table with a link to the record.
Then to display the list, you just query on UserActivity ordering by created_at descending, and then navigate through the polymorphic activity_source association to get the content data. You'll then need some smarts in your view templates to render comments and posts and whatever else differently though.
E.g. something like...
user_activity.rb:
class UserActivity < ActiveRecord::Base
belongs_to :activity_source, :polymorphic => true
# awesomeness continues here...
end
comment.rb (post/whatever)
class Comment < ActiveRecord::Base
# comment awesomeness here...
end
activity_source_observer.rb
class ActivitySourceObserver < ActiveRecord::Observer
observe :comment, :post
def after_create(activity_source)
UserActivity.create!(
:user => activity_source.user,
:activity_source_id => activity_source.id,
:activity_source_type => activity_source.class.to_s,
:created_at => activity_source.created_at,
:updated_at => activity_source.updated_at)
end
def before_destroy(activity_source)
UserActivity.destroy_all(:activity_source_id => activity_source.id)
end
end
Take a look at this railscast.
Then you can paginate 15 articles and in app/views/articles/index you can do something like this:
- #articles.each do |article|
%tr
%td= article.body
%tr
%td= nested_comments article.comment.descendants.arrange(:order => :created_at, :limit => 15)
This assumes the following relations:
#app/models/article.rb
has_one :comment # dummy root comment
#app/models/comment.rb
belongs_to :article
has_ancestry
And you add comments to an article as follows:
root_comment = #article.build_comment
root_comment.save
new_comment = root_comment.children.new
# add reply to new_comment
new_reply = new_comment.children.new
And so forth.
Hi: I'm struggling with a rails query. Finally, I want to make a JSON response with the following contents: A listing of all countries which have at least one company, associated through "Address" and a count of how of how many companies reside in a country.
Here is my simple model structure:
class Country < ActiveRecord::Base
has_many :addresses
end
class Address < ActiveRecord::Base
belongs_to :country
belongs_to :company
end
class Company < ActiveRecord::Base
has_one :address
end
What's the most elegant way to solve this with Rails?
You need to overload the to_json method :
class Country < ActiveRecord::Base
has_many :addresses
def to_json
# format your country as json with all the elements you need
end
end
Then in your controller do something like that:
countries = Country.find(:all).select{|c| c.companies.size > 0 }
json = countries.collect{|c| c.to_json }
You'll have to use has_many throught to get the companies from a country. Documentation here: http://api.rubyonrails.org/classes/ActiveRecord/Associations/ClassMethods.html
Sorry I don't have time for a more precise solution, but hopefully these pointers will help you. If you have specific problems, feel free to either comment or open a new question.
You might want to add a counter cache to Address
belongs_to :country, :counter_cache => :companies_count
It stores the number of companies in the country model, which saves you from the N+1 query issue.
Alternatively you could avoid it also by issuing a single query like this:
Country.find(:all, :select => 'countries.*, count(addresses.id) as companies_count', :joins => 'LEFT JOIN addresses ON addresses.country_id = countries.id', :group => 'countries.id')
This way all of the returned countries will have field companies_count containing the number of companies for that country.