I wanna iterate over all user's answers and order it by amount of likes which an answer has received, but I can't figure out how to do it, #user.answers.likes doesn't work, I found a way to find all user's answers which have likes, but that's not exactly what I want to do. Thank you for your help.
models/answer.rb
class Answer < ApplicationRecord
belongs_to :question
belongs_to :user
has_many :likes, dependent: :destroy
models/user.rb
class User < ApplicationRecord
has_many :answers
has_many :likes
models/like.rb
class Like < ApplicationRecord
belongs_to :user
belongs_to :answer
schema.rb
create_table "answers", force: :cascade do |t|
t.text "content"
t.datetime "created_at", null: false
t.datetime "updated_at", null: false
t.integer "question_id"
t.integer "user_id"
t.boolean "accepted", default: false
t.index ["question_id"], name: "index_answers_on_question_id"
end
create_table "likes", force: :cascade do |t|
t.integer "user_id"
t.integer "answer_id"
t.datetime "created_at", null: false
t.datetime "updated_at", null: false
end
Something like this should work in pure SQL.
sql = "SELECT * FROM answers INNER JOIN likes ON answers.id = likes.answer_id WHERE COUNT(likes.id) > 0 AND answers.user_id = #{#user.id} GROUP BY answers.id ORDER BY COUNT(likes.id)"
records_array = ActiveRecord::Base.connection.execute(sql)
#user.answers.joins(:likes)
.select('answers.*, COUNT(likes.id) as likes_count')
.group('answers.id')
.order('likes_count DESC')
If you want to select only answers with likes you can add having condition
#user.answers.joins(:likes)
.select('answers.*, COUNT(likes.id) as likes_count')
.group('answers.id')
.having('COUNT(likes.id) > 0')
.order('likes_count DESC')
Related
I am trying to make an association that is not working.
I have the following scope:
ActiveRecord::Schema.define(version: 2020_04_05_125812) do
create_table "accounts", force: :cascade do |t|
t.string "social_network"
t.string "name_account"
t.integer "person_id", null: false
t.datetime "created_at", precision: 6, null: false
t.datetime "updated_at", precision: 6, null: false
t.index ["person_id"], name: "index_accounts_on_person_id"
end
create_table "lists", force: :cascade do |t|
t.string "name"
t.datetime "created_at", precision: 6, null: false
t.datetime "updated_at", precision: 6, null: false
end
create_table "lists_people", id: false, force: :cascade do |t|
t.integer "list_id", null: false
t.integer "person_id", null: false
end
create_table "people", force: :cascade do |t|
t.string "name"
t.datetime "created_at", precision: 6, null: false
t.datetime "updated_at", precision: 6, null: false
end
create_table "posts", force: :cascade do |t|
t.string "post_text"
t.date "date"
t.string "link"
t.integer "account_id", null: false
t.datetime "created_at", precision: 6, null: false
t.datetime "updated_at", precision: 6, null: false
t.index ["account_id"], name: "index_posts_on_account_id"
end
add_foreign_key "accounts", "people"
add_foreign_key "posts", "accounts"
end
I wish I could consult, for example:
I want to consult the person named "Test_name"
That person belongs to lists, which is a collection of people. In addition, that person has accounts and those accounts have Posts.
class List < ApplicationRecord
has_and_belongs_to_many :people
end
class Person < ApplicationRecord
has_and_belongs_to_many :lists
end
class Account < ApplicationRecord
has_many :posts
belongs_to :person
end
class Post < ApplicationRecord
belongs_to :account
end
How could I have a return like the one below:
List | Name | social_network
1 | Test_name | facebook
2 | Test_name | twitter
All the queries I make, either return the wrong type, or return only the list.
Problems such as:
List | Name | social_network
1 | Test_name | facebook
2 | Test_name | twitter
1 | Second_name | twitter
And I don't want to see the data "second_name"
I try this:
#lists = List.from(
Person.left_outer_joins(:list).where('people.name LIKE ?', "Renata Rempel"),
:list
)
but, doesn't works =/
To start off with you want to setup a many to many association between Person and List. This can be done with has_and_belongs_to_many but there are many reasons why has_many through: may be a better choice. The primary one is that it will let you add features like keeping track of banned users or when a user joined a list.
# rails g model list_membership member:belongs_to user:belongs_to
class ListMembership < ApplicationRecord
belongs_to :member, class_name: 'Person'
belongs_to :list
end
We then have to fix the foreign key in the association:
class CreateListMemberships < ActiveRecord::Migration[6.0]
def change
create_table :list_memberships do |t|
t.belongs_to :list, null: false, foreign_key: true
t.belongs_to :member, null: false, foreign_key: { to_table: :people }
t.timestamps
end
# can be a good idea to add a compound index
# add_index [:list_id, :member_id], unique: true
end
end
class Person < ApplicationRecord
has_many :list_memberships, foreign_key: :member_id
has_many :lists, through: :list_memberships
has_many :accounts
has_many :posts, through: :accounts
end
class List
has_many :list_memberships
has_many :members,
through: :list_memberships
end
Your from query will not work as your actually selecting rows from people but you just alias the table lists. That won't magically select the right data! If you really wanted to use from you would do:
List.from(
List.joins(:members).where("people.name LIKE ?", "Renata Rempel"),
:lists
).eager_load(members: :posts)
If you want to create a bunch of lists with a random number of members in your seed file you can just do:
ids = 10.times.map do
Person.create!(name: Faker::Name.name).id
end
lists = 10.times.do
List.create!(member_ids: ids.sample(2))
end
I have 2 models (Books and Authors) and a third table joining them (has_many through association).
I am trying to implement search in my app and run a query on both tables. My query looks like this and I cannot figure out the problem:
Book.includes(:authors, :author_books).where("books.title LIKE ? OR authors.name = LIKE ?", "%#{book}%", "%#{book}%")
This is the error that I get running it:
PG::UndefinedTable: ERROR: missing FROM-clause entry for table "authors"
SELECT "books".* FROM "books" WHERE (books.title LIKE '%Harry%' OR authors.name = LIKE '%Harry%')
Here is my schema of the three tables:
create_table "author_books", force: :cascade do |t|
t.bigint "author_id"
t.bigint "book_id"
t.datetime "created_at", null: false
t.datetime "updated_at", null: false
t.index ["author_id"], name: "index_author_books_on_author_id"
t.index ["book_id"], name: "index_author_books_on_book_id"
end
create_table "authors", force: :cascade do |t|
t.string "name"
t.datetime "created_at", null: false
t.datetime "updated_at", null: false
end
create_table "books", force: :cascade do |t|
t.string "title"
t.text "description"
t.string "image"
t.datetime "created_at", null: false
t.datetime "updated_at", null: false
t.integer "rating"
t.string "critics"
t.float "price"
end
author_book.rb
class AuthorBook < ApplicationRecord
validates_presence_of :author, :book
belongs_to :author
belongs_to :book
end
author.rb
class Author < ApplicationRecord
validates :name, uniqueness: true
has_many :author_book
has_many :books, through: :author_book
end
book.rb
class Book < ApplicationRecord
validates :title, uniqueness: true, :case_sensitive => false
has_many :author_book
has_many :authors, through: :author_book
has_many :categories, through: :category_book
def self.search_book(book)
if book
Book.joins(:authors, :author_books).includes(:authors, :author_books).where("books.title LIKE ? OR authors.name = LIKE ?", "%#{book}%", "%#{book}%")
end
end
end
I call this search_book method in my book controller like so:
def search
#books = Book.search_book(params[:book])
end
Some help, please?
Thanks!
From the docs
If you want to add conditions to your included models you’ll have to
explicitly reference them.
That said, you need to add references(:authors) to your query like below to resolve the error
Book.includes(:authors, :author_books).where("books.title LIKE ? OR authors.name = LIKE ?", "%#{book}%", "%#{book}%").references(:authors)
Update:
Can't join 'Book' to association named 'author_books'; perhaps you
misspelled it?
You should replace has_many :author_book with has_many :author_books and through: :author_book with through: :author_books
You forgot to join authors and author_books to your relation. includes loads both :author and :author_books but in separate queries.
Try this:
Book.joins(:authors, :author_books).includes(:authors, :author_books).where("books.title LIKE ? OR authors.name = LIKE ?", "%#{book}%", "%#{book}%")
I don't know if anyone can help me as this is a little odd.
I have a moderately complicated set of relations in a database, which roughly has a structure something like this:
Delivery Director has Account Directors has Pods has Account Managers has Companies.
Therefore, Delivery Directors should have Companies.
This whole structure is working, all the way down to Companies, and then suddenly stops. The Delivery Director returns [] on companies.
class DeliveryDirector < User
has_many :account_directors
has_many :pods, through: :account_directors
has_many :account_managers, through: :pods
has_many :companies, through: :account_managers
end
And the company class looks like:
class Company < ApplicationRecord
belongs_to :account_manager
has_one :pod, through: :account_manager
has_one :account_director, through: :pod
has_one :delivery_director, through: :account_manager
end
Like I say, everything is working. The Company even has a Delivery Director! It's just the DeliveryDirector.all.first.companies returns [].
If anyone could even just point me in the right direction, that would be great. There is no error message, and nothing seems to be going wrong at all.
Oh, in case it helps, here is the SQL generated by the query:
Company Load (0.7ms) SELECT "companies".* FROM "companies" INNER JOIN "users" ON "companies"."account_manager_id" = "users"."id" INNER JOIN "pods" ON "users"."pod_id" = "pods"."id" INNER JOIN "users" "account_directors_companies" ON "pods"."account_director_id" = "account_directors_companies"."id" WHERE "users"."type" IN ('AccountDirector') AND "account_directors_companies"."delivery_director_id" = $1 [["delivery_director_id", 2]]
Thanks!
Edit: Request for other models, schema
Pod:
class Pod < ApplicationRecord
belongs_to :account_director
has_many :account_managers
has_many :companies, through: :account_managers
end
Account Manager:
class AccountManager < User
belongs_to :pod
has_one :account_director, through: :pod
has_one :delivery_director, through: :account_director
has_many :companies
end
Schema:
ActiveRecord::Schema.define(version: 2018_10_19_141416) do
enable_extension "plpgsql"
create_table "companies", force: :cascade do |t|
t.string "name"
t.string "officelocation"
t.datetime "created_at", null: false
t.datetime "updated_at", null: false
t.string "campaign_link"
t.string "company_logo"
t.string "website"
t.integer "account_manager_id"
end
create_table "images", force: :cascade do |t|
t.string "name"
t.string "location"
t.bigint "company_id"
t.datetime "created_at", null: false
t.datetime "updated_at", null: false
t.index ["company_id"], name: "index_images_on_company_id"
end
create_table "jwt_blacklist", id: :serial, force: :cascade do |t|
t.string "jti", null: false
t.index ["jti"], name: "index_jwt_blacklist_on_jti"
end
create_table "markets", force: :cascade do |t|
t.string "name"
t.datetime "created_at", null: false
t.datetime "updated_at", null: false
end
create_table "markets_users", id: false, force: :cascade do |t|
t.bigint "market_id", null: false
t.bigint "talent_manager_id", null: false
end
create_table "pods", force: :cascade do |t|
t.string "name"
t.integer "account_director_id"
t.integer "delivery_director_id"
t.datetime "created_at", null: false
t.datetime "updated_at", null: false
end
create_table "table_campaigns", force: :cascade do |t|
t.bigint "user_id"
t.bigint "company_id"
t.string "name"
t.integer "iterations"
t.integer "interviews"
t.index ["company_id"], name:
"index_table_campaigns_on_company_id"
t.index ["user_id"], name: "index_table_campaigns_on_user_id"
end
create_table "users", force: :cascade do |t|
t.string "name"
t.string "jobtitle"
t.string "linkedin"
t.string "office"
t.datetime "created_at", null: false
t.datetime "updated_at", null: false
t.string "type"
t.integer "team_lead_id"
t.integer "delivery_director_id"
t.string "email", default: "", null: false
t.string "encrypted_password", default: "", null: false
t.string "reset_password_token"
t.datetime "reset_password_sent_at"
t.datetime "remember_created_at"
t.integer "sign_in_count", default: 0, null: false
t.datetime "current_sign_in_at"
t.datetime "last_sign_in_at"
t.inet "current_sign_in_ip"
t.inet "last_sign_in_ip"
t.bigint "pod_id"
t.string "user_photo"
t.index ["email"], name: "index_users_on_email", unique: true
t.index ["pod_id"], name: "index_users_on_pod_id"
t.index ["reset_password_token"], name:
"index_users_on_reset_password_token", unique: true
end
add_foreign_key "table_campaigns", "companies"
add_foreign_key "table_campaigns", "users"
end
And now adding Account Director:
class AccountDirector < User
belongs_to :delivery_director
has_one :pod
has_many :account_managers, through: :pod
has_many :companies, through: :account_managers
end
You use Single Table Inheritance. 3 of your models: DeliveryDirector, AccountDirector and AccountManager are descendants of User model. When doing shallow request it works fine, but when you construct requests which involve all 3 models Rails cannot build the right query. If you try to project how to find all companies of a delivery director in terms of database, you will come to the chain of tables:
companies -> users (account managers) -> pods -> users (account directors) -> users (delivery directors)
The SQL query for your request may look like:
SELECT companies.* FROM companies
INNER JOIN users AS account_managers ON companies.account_manager_id = account_managers.id
INNER JOIN pods ON account_managers.pod_id = pods.id
INNER JOIN users AS account_directors ON pods.account_director_id = account_directors.id
INNER JOIN users AS delivery_directors ON account_directors.delivery_director_id = delivery_directors.id
WHERE delivery_directors.id = 2;
but obviously, Rails does not add AS clause to the query to distinguish user roles and uses users table name instead. To filter results it uses condition "users"."type" IN ('AccountDirector') which is not enough in your case, because in your query there should be also AccountManager (as a link between pods and companies).
Another sign that Rails is confused: despite correct association in your models Rails tries to use table account_directors_companies which you obviously do not have.
I would recommend to review your database schema and extract user roles and relationship between them into separate substances.
UPDATE:
For example, user authentication/registration data can be left in users table as it is now. All info about user roles and their relations can be moved to extra tables, backed up by models:
class DeliveryDirector < ApplicationRecord
belongs_to :user
has_many :account_directors
has_many :pods, through: :account_directors
has_many :account_managers, through: :pods
has_many :companies, through: :account_managers
end
class AccountDirector < ApplicationRecord
belongs_to :user
has_one :pod
has_many :account_managers, through: :pod
has_many :companies, through: :account_managers
end
class AccountManager < ApplicationRecord
belongs_to :user
has_many :companies
end
Each of these models has their own table in the database.
Thus, to fetch companies of delivery director you could call:
DeliveryDirector.find_by(user_id: user_id).companies
Having three models: Datum, Author, and Book .
class Datum < ApplicationRecord
has_many :authors
end
class Book < ApplicationRecord
belongs_to :author
end
class Author < ApplicationRecord
belongs_to :datum
has_many :books, dependent: :destroy
end
For exercise purpose, I wanted to model it that Datum(more general), can have many authors, which can have books.
After creating a datum object and an associated author for it, I could call nameofdatum.authors, but if I added a book to that author, it could not be recognized through nameofdatum.authors.books. Am I having wrong expectations ? (Should this be done with 'through'(an explanation of it would be much appreciated)
(Schema here if needed)
create_table "authors", force: :cascade do |t|
t.string "name"
t.integer "age"
t.datetime "created_at", null: false
t.datetime "updated_at", null: false
t.integer "book_id"
t.integer "datum_id"
t.index ["book_id"], name: "index_authors_on_book_id"
t.index ["datum_id"], name: "index_authors_on_datum_id"
end
create_table "books", force: :cascade do |t|
t.string "name"
t.string "book_type"
t.integer "pages"
t.datetime "created_at", null: false
t.datetime "updated_at", null: false
t.integer "author_id"
t.index ["author_id"], name: "index_books_on_author_id"
end
create_table "data", force: :cascade do |t|
t.string "region"
t.integer "budget"
t.date "aval"
t.datetime "created_at", null: false
t.datetime "updated_at", null: false
end
Should this be done with 'through'?
Yes, Datum has_many books through the authors assocition:
class Datum < ApplicationRecord
has_many :authors
has_many :books, through: :authors
end
And the books can be selected via:
Datum.last.books
It's actually selects books using the following query:
SELECT "books".* FROM "books" INNER JOIN "authors" ON "authors"."id" = "books"."author_id" WHERE "authors"."datum_id" = ?
If you want to add a new book through author, you have to assign an author. So you can try:
nameofdatum.author.books.build ....
your codenameofdatum.authors.books, you can't use a plural(author) to add a new book.
Hope to help you.
I have articles that are able to be tagged in categories. I am struggling to create a query which will extract the sum of view count (tracked using impressionist gem) of articles within each category.
Schema:
create_table "article_categories", force: :cascade do |t|
t.integer "article_id"
t.integer "category_id"
end
create_table "articles", force: :cascade do |t|
t.string "title"
t.text "description"
t.bigint "user_id"
t.datetime "created_at", null: false
t.datetime "updated_at", null: false
t.integer "impressions_count", default: 0
end
create_table "categories", force: :cascade do |t|
t.string "name"
t.datetime "created_at", null: false
t.datetime "updated_at", null: false
end
Article model
class Article < ApplicationRecord
is_impressionable :counter_cache => true, :unique => false
belongs_to :user
has_many :impressions, as: :impressionable
has_many :article_categories
has_many :categories, through: :article_categories
end
Category model
class Category < ApplicationRecord
has_many :article_categories
has_many :articles, through: :article_categories
end
ArticleCategory model
class ArticleCategory < ActiveRecord::Base
belongs_to :article
belongs_to :category
end
Here is what i have tried so far and the errors when i test in rails console:
cat_group = Article.joins(:article_categories).group_by(&:category_ids)
// this query results in an array of articles within each category
1) cat_group.sum("impressions_count")
//TypeError: no implicit conversion of Array into String
2) cat_group.select("sum(impressions_count) AS total_count")
//ArgumentError: wrong number of arguments (given 1, expected 0)
3) Article.joins(:article_categories).group(:category_id)
//ActiveRecord::StatementInvalid: PG::GroupingError: ERROR: column "articles.id" must appear in the GROUP BY clause or be used in an aggregate function
If I understand you correctly and view count is impressions_count, here is query that you can use:
Article.joins(:categories).group('categories.name').sum(:impressions_count)