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Questions tagged [active-relation]

A Ruby Relational Algebra Library

Active Relation also known as "Arel" is the Relational Algebra library used in Active Record and Ruby on Rails.

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Initialise model object from table name

Is there a way to instantiate a namespaced model object from its table name? eg: Given table school_students, model School::Student, id 30, I could do: student = get_from_table_name_and_id("school_students", 38)
zsquare
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What's the ActiveRelation (arel) equivalent to :from

I have this named_scope in one of my models: named_scope :latest_100, :from => '(select * from videos order by videos.created_at desc limit 0, 100) as videos' Its purpose is to create a pool of the last 100 videos (returning that…
Paul Gibler
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Active Relation: Retrieving records through an association?

I have the following models: class User < ActiveRecord::Base has_many :survey_takings end class SurveyTaking < ActiveRecord::Base belongs_to :survey def self.surveys_taken # must return surveys, not survey_takings where(:state =>…
Jay Levitt
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Link two models through middlemodel at Rails 3.x

I guess that I do not know the right terminology yet, thus find it difficult to find the right answer. So, I have created an engine with Exhibit and Category. I created a third model Categorization so as to assign an exhibit to more than one…
Cacofonix
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Rails :include doesn't include

My models: class Contact < ActiveRecord::Base has_many :addresses has_many :emails has_many :websites accepts_nested_attributes_for :addresses, :emails, :websites attr_accessible :prefix, :first_name, :middle_name, :last_name, :suffix, …
Micah Alcorn
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How to sort forum's users by "total_content_length" and then by most recent post?

I would like to sort forum's users by total_content_length. To get the top n writers in the forum I do: User.order("total_content_length DESC").limit(n) Now, the problem is when there are two (or more) users with the same total_content_length. In…
Misha Moroshko
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Standard sql subquery to ActiveRecord Relation, is it possible?

I've got a piece of code where I have to applies some subqueries. I'm trying to change this piece of pure sql to more rails way. Is it possible to implement ActiveRecord Relation here? Customer.joins("RIGHT JOIN customers_users ON…
mr_muscle
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why is message_id_equals method missing in Rails 3?

I seem to have this error, and I'm not doing anything special: NameError (undefined method `message_id_equals' for class `ActiveRecord::Relation') Why? Here is the context: @user_has_message =…
Satchel
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DRYing up Active Record Queries

I have 2 queries that are similar, how can I DRY them up? There is only 1 condition that is different between both queries. if self.gender_target == "Both" return Drop.limit(180).live.where( :drops => {:navigation_section_id => 1} …
jdee
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Using after_create

I have a model, Category. And I want to create an new default sub_category when ever the category is created. But I'm not sure how to do it. Here is what I have. class Category < ActiveRecord::Base attr_accessible :title, :position has_many…
Antarr Byrd
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NULL in (NULL) does not match properly

Using Rails 3 active relation, I have a scope: scope :duplicate_contact, lambda {|contact| where( :person_id => contact.person_id, :salutation => contact.salutation, …
DGM
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How do I model different types of users?

My app will be a database of players. That's the core data point of the database. Players (aka...the profiles of players) are what users will login to view/edit/update/delete. Think of it like a recruiting database, where I (as a recruiter) can…
marcamillion
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How to combine two ActiveRecord::Relation to form active relation under OR condition?

This link is great but it doesn't address the problem of getting an active_relation after combining two active relation under or condition. There are other links as well but none of them answer the above question. Although for anding method merge…
zeal
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sql: DISTINCT give me duplicate results

Hello I am using following query Message.select("DISTINCT(commentable_id, user_id) as owner_id").map(&:owner_id) It gives me the result like this: ["(8,9)", "(8,84)", "(9,8)", "(84,8)"] here "(8, 9)" and "(9, 8)" are returns as different, but I…
sunil
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Using ActiveRelation with :joins on polymorphic has_one to implicitly create relation

We can use ActiveRelation like this: MyModel.where(:field => "test").create => # But it doesnt work for joins with polymorphic has_one associations: class RelatedModel < AR::Base # has :some_field belongs_to :subject,…
Bombazook
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