May 14, 2016 Here, a foreign key of 1 in the categoryid column will relate to food expenses, a foreign key of 2 will relate to accommodation expenses, and so forth. Let's dive in. Generate Models. To start off, I created a new rails application and established the primary database, expenses. Advanced Rails model generators rails. There are some people who give advice to not use rails generators and create models, controllers and etc. Things manually. I don’t agree with them and my advice here is to figure out deeply how they work and then make conclusion. Oct 07, 2016 Of course, thanks to Rails Generators I didn’t have to type all of that out by hand, I was able to use Rails’ Model Generator to generate the Models and the Migrations using the commands rails generate model Cat name:string and rails generate model Snack name:string catid:integer.
Immigrant gives Rails a foreign key migration generator so you caneffortlessly find and add missing keys. This is particularly helpfulwhen you decide to add keys to an established Rails app.
Installation
Add the following to your Gemfile:
Rails Create Model With Foreign Key
download mac os sierra full installer If you're using a version of Rails prior to 4.2, you'll also need theForeigner gem.
Usage
This will create a migration named AddKeys which will have add_foreign_keystatements for any missing foreign keys. Immigrant infers missing ones byevaluating the associations in your models (e.g. belongs_to, has_many, etc.).Only missing keys will be added; existing ones will never be altered orremoved.
Rake Task
To help you remember to add keys in the future, there's a handy raketask you can add to your CI setup. Just run rake immigrant:check_keys,and if anything is missing it will tell you about it and exit with anon-zero status.
Skipping associations
Immigrant.ignore_keys allows you to specify a list of keys that shouldbe ignored (both in the migration generator and the rake task). This isuseful if you have associations spanning databases.
Just create an config/initializers/immigrant.rb file with something likethe following:
Considerations
If the data in your tables is bad, then the migration will fail to run(obviously). IOW, ensure you don't have orphaned records before you try toadd foreign keys.
Known Issues
Immigrant currently only looks for foreign keys in ActiveRecord::Base'sdatabase. So if a model is using a different database connection and it hasforeign keys, Immigrant will incorrectly include them again in the generatedmigration. Immigrant.ignore_keys can be used to work around this.
License
Rails Migration Foreign Key
Copyright (c) 2012-2015 Jon Jensen, released under the MIT license /steam-wallet-key-generator-2014.html.
Coments are closed