Ruby on rails distinct

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August undefined, 2024

Webb> User.joins(:donations).order('donations.created_at').uniq.count (3.2ms) SELECT DISTINCT COUNT(DISTINCT "users"."id") FROM "users" INNER JOIN "donations" ON … WebbI think the simplest way, without directly using the Arel API or iterating over arrays, would be to define .titles_for_comments scopes on both Book and Article that let you select distinct titles from each table when given a collection of comments.Then define a .distinct_titles scope for Comment that uses both [Book Article].titles_for_comments.For …

ruby-on-rails - 根據ID數組對活動記錄進行排序 - 堆棧內存溢出

Webb[英]How to validate uniqueness then suggest a unique alternative on fail ... 142 ruby-on-rails / ruby / rspec / ruby-on-rails-4.2. 在rails中，如何驗證不是唯一性的字段？ [英]in rails, how to validate a fields which is NOT uniqueness? 2010-05-27 06:32:37 1 217 ... Webb22 nov. 2010 · Instead of using an Array, consider using either a Hash or a Set. Sets behave similar to an Array, only they contain unique values only, and, under the covers, are built … tires chatham ontario

In Rails- how do you get the distinct rows from X column and from …

Webb6 apr. 2024 · Author. Adam Hess. April 6, 2024. Since the beginning, GitHub.com has been a Ruby on Rails monolith. Today, the application is nearly two million lines of code and more than 1,000 engineers collaborate on it daily. We deploy as often as 20 times a day, and nearly every week one of those deploys is a Rails upgrade. Webbadd_index :campaigns, [:appeal_id, :user_id], unique: true in my migration. Then run the command. rails db:create db:migrate which actually created my database again and resolved the issue of unique index. WebbRuby on Rails Tutorial => Add an unique column to a table eBooks Ruby on Rails ActiveRecord Migrations Add an unique column to a table Fastest Entity Framework Extensions Bulk Insert Bulk Delete Bulk Update Bulk Merge Example # To add a new unique column email to users, run the following command: tires chatham kent

Active Record Query Interface — Ruby on Rails Guides

ruby on rails - Pluck unique values from an ActiveRecord …

Webb29 sep. 2014 · uniq is a method of Array, so it returns the whole bunch of 120k users and iterates through them one by one using ruby to check the condition. This is definetely the wrong way to do filtering. On the other hand, DISTINCT(users.id) is SQL condition which is handled by your PostgreSQL server. This one should be executed pretty fast. In case it … Webb127. All the above answers are missing how to validate the uniqueness of multiple attributes in a model. The code below intends to tell how to use multiple attributes in a scope. validates :country, uniqueness: { scope: [:medium, :another_medium] } It validates uniqueness of country in all rows with values of medium and another_medium. tires chapman hwy knoxWebb7 aug. 2015 · In Rails 4, has_many :products, :through => :orders, :uniq => true is deprecated. Instead, you should now write has_many :products, -> { distinct }, through: … tires chatham

"Webb31 jan. 2016 · 3. I have the following association: Artist has_many Songs. Hence, I can get an artist's songs by doing: artist.songs. However, I would like to get only the songs' genre: artist.songs.pluck (:genre) But, this genre may appear multiple times in the results; I would only like to get unique genre values. Unfortunately, pluck isn't of any help here ... " - Ruby on rails distinct

Ruby on rails distinct

ruby on rails - PG::Error: SELECT DISTINCT, ORDER BY expressions …

Webb28 okt. 2024 · @GLaDOS yes, rails app is like a building: on the first floor we have sql, on the second and others we have business logic, on the last floor we have a view for users.1) In case if user doesn't need any data, we should not lift the data from the first floor to last. So it means we shouldn't fetch the data on sql layer, not to lift it on rails one (so use … Webbför 17 timmar sedan · Rails: ジョブの中で関連付けをループしないこと（翻訳）. SQLを直接使わずにRubyでデータベースとやりとりする方法は、ともすると、ほとんど同じようなクエリをうっかり大量に実行してパフォーマンス低下で頭を抱えがちですが、それでもActive Record（また ...

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WebbRuby-on-Rails: Selecting distinct values from the model Ask Question Asked 9 years, 8 months ago Modified 3 years, 9 months ago Viewed 77k times 29 The docs: http://guides.rubyonrails.org/active_record_querying.html#selecting-specific-fields … WebbAs written it's pretty confusing. If you're using postgres it supports "distinct on" which makes it relatively easy to do this directly in the database. That would look like: SELECT …

WebbRails is a web application development framework written in the Ruby programming language. It is designed to make programming web applications easier by making assumptions about what every developer needs to get started. It allows you to write less code while accomplishing more than many other languages and frameworks. Webb8 dec. 2014 · In Rails, how can I get all distinct values from a column, as an array? Matches ----- winner_id loser_id 1 2 1 3 1 4 1 5 I want to get all the distinct IDs in winner_id column, …

WebbRuby on Rails, disebut juga Rails, adalah sebuah kerangka kerja aplikasi web sumber terbuka yang berjalan via bahasa pemrograman Ruby. Ia merupakan kerangka kerja full-stack : memampukan pembuatan laman dan aplikasi yang mengumpulkan informasi dari server web, berkomunikasi dengan atau memanggil sebuah kueri dari server web, dan … WebbI recently worked on a clone of the website PetFinder, utilizing React, Redux, and Ruby on Rails. I've also recently built a unique social media …

Webb9 okt. 2024 · The Polymorphic association is a Ruby on Rails feature that gives us the freedom to structure model relationships based on real life. This means building cleaner more semantic databases. In a…

Webb15 mars 2024 · ActiveRecord Rails: Get records where a field is unique/distinct. I have a project Ruby 2.4.0 and Rails 5.0.1 and a model with the following: class Hospital < … tires change how oftenWebb31 dec. 2024 · You would have to look up the genre table to get the 'Action' string returned. If you have to make a link from the movie to genre table, that will go something like this: movies = Movie.includes (:genre) movies.first.genre.name # this will return the action string # or, pick a specific movie and look up its genre movies.where (:title => 'xyz ... tires centers near meWebbSo, first, we’ll set up a User class and we’ll be using it in our examples. ‘class User < ApplicationRecord. end’. A User model only represents a Users table, the model itself is not the table. In the database, a Users table has tables and rows while in … tires causeway metairieWebb15 juli 2024 · It’s quite easy to set database unique index (es) for any column or set of columns in rails. However, some database constraint in rails can be tricky. A quick look at setting a unique index for one or more column This is quite as simple as running a … tires chelsea alWebb5 apr. 2024 · The ORDER BY clause can only be applied after the DISTINCT has been applied. Since only the fields in the SELECT statement are taken into consideration for the DISTINCT operations, those are the only fields may be used in the ORDER BY. Logically, if you just want a distinct list of event_id values, what order they occur in should be … tires check near meWebbadd_index :campaigns, [:appeal_id, :user_id], unique: true in my migration. Then run the command. rails db:create db:migrate which actually created my database again and … tires cherokee ncWebb31 jan. 2016 · If using the artist's songs association, you can select distinct on genre, then map over the results to just return the strings: artist.songs.select('distinct … tires cheap new