On the relationships for both User and Target, tack on a ->withPivot(‘type’) which will instruct Laravel to include that column. Then once you have your result set, you can access the field with $user->pivot->type. If you’re not iterating over a collection, but have a user and one of their targets and want the type field, … Read more
tldr; Use sync with 2nd param false Many-to-many relationship is belongsToMany on both models: // Task model public function users() { return $this->belongsToMany(‘User’, ‘user_tasks’); // assuming user_id and task_id as fk } // User model public function tasks() { return $this->belongsToMany(‘Task’, ‘user_tasks’); } In order to add new relation use attach or sync. Difference between … Read more
No, you can’t do that, there’s no such thing as a polymorphic has_and_belongs_to_many association. What you can do is create a middle model. It would probably be something like this: class Subscription < ActiveRecord::Base belongs_to :attendee, :polymorphic => true belongs_to :event end class Event < ActiveRecord::Base has_many :subscriptions end class User < ActiveRecord::Base has_many :subscriptions, … Read more
The better way, programmatically speaking, is gathering data from INFORMATION_SCHEMA.KEY_COLUMN_USAGE table as follows: SELECT `TABLE_SCHEMA`, — Foreign key schema `TABLE_NAME`, — Foreign key table `COLUMN_NAME`, — Foreign key column `REFERENCED_TABLE_SCHEMA`, — Origin key schema `REFERENCED_TABLE_NAME`, — Origin key table `REFERENCED_COLUMN_NAME` — Origin key column FROM `INFORMATION_SCHEMA`.`KEY_COLUMN_USAGE` — Will fail if user don’t have privilege WHERE … Read more
Here’s a complete answer to this issue, in case people visiting this question are new to Ruby on Rails and having a hard time putting everything together (as I was when I first looked into this). Some parts of the solution take place in your Migrations and some in your Models: Migrations class CreatePrivateMessages < … Read more
attach(): Insert related models when working with many-to-many relations No array parameter is expected Example: $user = User::find(1); $user->roles()->attach(1); sync(): Similar to the attach() method, the sync() method is used to attach related models. However, the main differences are: sync() accepts an array of IDs to place on the pivot table Secondly, most important, the … Read more
There’s nothing inherently wrong with having a many-to-many relationship, you’ll just need to create a Junction Table (which is what it sounds like you’re referring to with articlesTags) to facilitate that relationship.
Chriss I hope this simple example helps. Guess you have a Java class public class A { private B b; … } In UML you would model this relationship as an association from A to B: A -> B with the following modeling elements: Class B Class A + Property b : B [0..1] (owned … Read more
m:n is used to denote a many-to-many relationship (m objects on the other side related to n on the other) while 1:n refers to a one-to-many relationship (1 object on the other side related to n on the other).
Composition final class Car { private final Engine engine; Car(EngineSpecs specs) { engine = new Engine(specs); } void move() { engine.work(); } } Aggregation final class Car { private Engine engine; void setEngine(Engine engine) { this.engine = engine; } void move() { if (engine != null) engine.work(); } } In the case of composition, the … Read more