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Multiple associations query - DB Modelling


Multiple associations query - DB Modelling

By : Jon
Date : November 18 2020, 01:01 AM
Hope this helps I am planning a rails apps that allows a User to list one/many Vaults, at either their personal address or any other additional address (location) specified against a vault. Before I go ahead and generate the Models I want to make sure I understand what associations need to be set up between the three Models. Here the code representation that I have typed manually to depict what associations are required. , Your database looks okay, few consideration are below :
code :
class User < ActiveRecord::Base
  has_many :vaults
  has_many :addresses #(optional)if you want to fetch addresses directly
end

class Vault < ActiveRecord::Base
  belongs_to :user
  has_one :address
end

class Address < ActiveRecord::Base
  belongs_to :user #(optional) if you want to fetch user directly
  belongs_to :vault
end


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Model Associations and Data Modelling

Model Associations and Data Modelling


By : justinMnewhouse
Date : March 29 2020, 07:55 AM
should help you out It's possible to use CakePHP's bindModel & unbindModel to build up relations that don't rely on Cake's automagic goodness.
Since you were interested in doing the find on the Product model, I'll set out an example that can be called from the Products controller:
code :
// unbind Artist
$this->Product->unbindModel(array(
  'belongsTo' => array('Artist')
));

// bind Artist & Person using explicit conditions
$this->Product->bindModel(array(
  'hasOne' => array(
    'Artist' => array(
      'foreignKey' => false,
      'conditions' => array('Artist.id = Product.artist_id')
    ),
    'Person' => array(
      'foreignKey' => false,
      'conditions' => array('Person.id = Artist.person_id')
    ),
  )
));

// return the person
$person = $this->Product->find('first', array(
  'conditions' => array(
    'Product.id' => 1 // or any other condition
  ),
  'fields' => array(
    'Person.first_name',
    'Person.last_name'
  )
));
Modelling polymorphic associations database-first vs code-first

Modelling polymorphic associations database-first vs code-first


By : GIFTFY
Date : March 29 2020, 07:55 AM
I hope this helps you . I personally stick with Database first when using EF on any schema that is this level of complexity. I have had issues with complex schemas in regards to code first. Maybe the newer versions are a little better, but worrying how to try and code complex relationships seems less straight forward then allowing the engine to generate it for you. Also when a relationship gets this complex I tend to avoid trying to generate it with EF and try and use stored procedures for easier troubleshooting of performance bottlenecks that can arise.
Modelling Many Rails Associations

Modelling Many Rails Associations


By : jeremygio
Date : March 29 2020, 07:55 AM
hope this fix your issue I'm trying to wrap my head around how I should model my database for a parent model with many has_one associations (20+). I have one model called House which is the parent model of all the other models:
code :
class House
  has_many :rooms
  Room::TYPES.each do |room_type|
    has_one room_type, -> { where(room_type: room_type) }, class_name: "Room"
  end

class Room
  belongs_to :house
  TYPES = %i/kitchen basement garage common_room etc/.freeze
end
Modelling associations to Java Enums in UML Class diagrams

Modelling associations to Java Enums in UML Class diagrams


By : pafmaf
Date : March 29 2020, 07:55 AM
around this issue You're doing it almost right. A directed association is the correct relationship for this situation.
To clarify that the association refers to a specific attribute in the class, use a target role. This is displayed as a text label with the name of the attribute (fuelKind) at the enumeration end (not the class end) of the connector.
Modelling an application in Rails - mixing STI and polymorphic associations

Modelling an application in Rails - mixing STI and polymorphic associations


By : Julien Roussel
Date : March 29 2020, 07:55 AM
To fix this issue It's probably too late but you could also use has_and_belongs_to_many on User and Company and thus avoid STI altogether by using gems cancan and rolify. It allows you to define finely grained access rights (abilities).
I know that it seems more elegant having different classes instead of roles, but it is not viable long-term strategy, it can become messy when logic becomes complex.
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