associations

问题 I'm using sequelize-cli for migrations and have researched different scenarios but there doesn't seem to be a definite solid answer as to how to self join. I want to have a join table called friendships which joins users and friends (which are essentially just users). More specifically trying to gain an understanding about the difference between "through" and "as" in this situation. 1) This is my friendship table. Getting tripped up on the second association. I have created two columns, one

问题 I'm using sequelize-cli for migrations and have researched different scenarios but there doesn't seem to be a definite solid answer as to how to self join. I want to have a join table called friendships which joins users and friends (which are essentially just users). More specifically trying to gain an understanding about the difference between "through" and "as" in this situation. 1) This is my friendship table. Getting tripped up on the second association. I have created two columns, one

问题 I have a has_many association between two models using a date as both the foreign and primary key for each model. It works perfectly one way but not the other. Works has_one :quiz_log, :primary_key => :start_at, :foreign_key => :start_at Doesn't work has_many :event_logs, :primary_key => :start_at, :foreign_key => :start_at The reason being (i think) because the start_at on QuizLog is a date and the start_at on EventLog is a datetime . So it returns nil trying to match the exact datetime on a

问题 I have a has_many association between two models using a date as both the foreign and primary key for each model. It works perfectly one way but not the other. Works has_one :quiz_log, :primary_key => :start_at, :foreign_key => :start_at Doesn't work has_many :event_logs, :primary_key => :start_at, :foreign_key => :start_at The reason being (i think) because the start_at on QuizLog is a date and the start_at on EventLog is a datetime . So it returns nil trying to match the exact datetime on a

问题 In Rails 2.2.2 (ruby 1.8.7-p72), I'd like to evaluate the impact of destroying an object before actually doing it. I.e. I would like to be able to generate a list of all objects that will be affected by :dependent => :destroy (via an object's associations). The real problem I'm trying to solve is to give a user a list of everything that will be deleted and having them confirm the action. Can anyone recommend a good way to go about this? I've just started looking into ActiveRecord:

问题 In Rails 2.2.2 (ruby 1.8.7-p72), I'd like to evaluate the impact of destroying an object before actually doing it. I.e. I would like to be able to generate a list of all objects that will be affected by :dependent => :destroy (via an object's associations). The real problem I'm trying to solve is to give a user a list of everything that will be deleted and having them confirm the action. Can anyone recommend a good way to go about this? I've just started looking into ActiveRecord:

问题 hoping a grandmaster can shed some light. Very high overview is that I am no beginner to coding, but still new to OOP. This set of message classes is at the heart of a large simulation application we're writing, and I don't want to do it stupidly--this interface cuts the application in half, from sequencer to executer and vice-versa. My question is whether or not it's a bad idea to have an inheritance hierarchy this deep (image is not yet fleshed out, might go 5 or 6 deep in the end). This is

问题 I followed the steps from here to setup a favorites relationship between a user model and a company model. Specifically, a user can have many favorite companies. There is also a functionality of a user being tied to a company on creation. So here are my current models/routes/db schema Models class FavoriteCompany < ActiveRecord::Base belongs_to :company belongs_to :user ... class User < ActiveRecord::Base has_many :companies has_many :favorite_companies has_many :favorites, through: :favorite

问题 I'm trying to implement a global search mechenism in my CakePHP 3.3.15 app - this involves searching the Parent table for a value plus searching all the associated tables for the same value. I'm using matching() , but I can't find a way to combine multiple matching() into one query object using OR . It looks like matching() will narrow down the result set and calling matching() consecutively will use the object modified by the previous matching() call. This is what I have: $query = $this->

问题 I'd like to be sure if vestal_versions does support versioned associations (it seems like it doesn't) before switching out to another versioning gem that can support versioned associations e.g => has_versioning. I haven't looked at the code yet but I couldn't find anything related with versioned associations from the readme file or the issue section on github. Help would be appreciated! 回答1: (At the moment of writing this) There is an associations branch in the official vestal_versions