Rails Remove child association from parent
How about this: @contract.accessories.delete(@accessory) See also: How do I remove a single HABTM associated item without deleting the item itself?
activerecord
Issue when retrieving records with empty array
In Rails 4 you can use User.where.not(id: []) which will give you the correct result. It produces: SELECT “users”.* FROM “users” WHERE (1 = 1) Unfortunately User.where(‘id NOT IN (?)’, []) should be equivalent but it is not. It still gives you the wrong result: SELECT “users”.* FROM “users” WHERE (id NOT IN (NULL)) References: … Read more
How do I set up a kind of “belongs_to :through” association without a direct belongs_to?
Use delegate in the model class. class Team < ActiveRecord::Base belongs_to :division has_many :players delegate :league, to: :division end Reference: http://api.rubyonrails.org/classes/Module.html#method-i-delegate
Merge two ActiveRecord arrays and order by created_at
You’re very close. Concatenating the arrays is done with the plus sign: materials = books + articles Sorting the combined array can be done by calling the sort_by method (mixed in from Enumerable) and passing in the attribute prefixed with &: materials.sort_by(&:created_at) This won’t be good performance-wise for large result sets. You might consider deriving … Read more
CodeIgniter: INSERT multiple records without cycle
Codeigniter active record has a function insert_batch i think that is what you need $data = array( array( ‘title’ => ‘My title’ , ‘name’ => ‘My Name’ , ‘date’ => ‘My date’ ), array( ‘title’ => ‘Another title’ , ‘name’ => ‘Another Name’ , ‘date’ => ‘Another date’ ) ); $this->db->insert_batch(‘mytable’, $data); // Produces: INSERT … Read more
How can I have ActiveRecord’s pluck also return the column name for rendering in json?
vee’s answer is good, but I have one caveat. select instantiates a User for every row in the result, but pluck does not. That doesn’t matter if you are only returning a few objects, but if you are returning large batches (50, 100, etc) you’ll pay a significant performance penalty. I ran into this problem, … Read more
Find ActiveRecord object by maximum field value of a child object?
@parent.children.order(“value DESC”).first
Correct setting of database connection pool database.yml for single-threaded Rails applications
Quite late to the party here, but I ran out of database connections today in production. Like a lot of people, I use Sidekiq to perform asynchronous jobs like sending emails for example. It is important to note that Sidekiq runs as a multithread process. So, I don’t just have a single-threaded Rails application, therefore … Read more
has_many :through : How do you access join table attributes?
The answer may be different regarding what you want to achieve. Do you want to retrieve those attributes or to use them for querying ? Loading results ActiveRecord is about mapping table rows to objects, so you can’t have attributes from one object into an other. Let use a more concrete example : There are … Read more
When to use “validates_associated” v “validate => true”
I had to dig into the Rails (3.0.7) code to find some differences. The core functionality looks the same to me — they both seem to call valid? on the associated record(s). The key differences that I did find only appear when using the :autosave feature or when either destroying the associated object or marking … Read more