Existing ones will never be altered or removed.
Ruby on rails generate model with foreign key.
There is a name option to specify a different name if needed.
Here a foreign key of 1 in the category id column will relate to food expenses a foreign key of 2 will relate to accommodation expenses and so forth.
The association foreign key option lets you set the name of the foreign key directly.
I m learning the basics of ruby on rails and i want to make some simple queries but i have a doubt.
If the column names cannot be derived from the table names you can use the column and primary key options.
Belongs to has many etc only missing keys will be added.
I will have these models.
To start off i created a new rails application and established the primary database expenses.
Adds a new foreign key.
The foreign key will be named after the following pattern.
By convention rails guesses that the column in the join table used to hold the foreign key pointing to this model is the name of this model with the suffix id added.
By convention rails assumes that the column in the join table used to hold the foreign key pointing to the other model is the name of that model with the suffix id added.
From table is the table with the key column to table contains the referenced primary key.
Immigrant infers missing ones by evaluating the associations in your models e g.
Rails will generate a name for every foreign key starting with fk rails followed by 10 characters which are deterministically generated from the from table and column.
Fk rails identifier identifier is a 10 character long string which is deterministically generated from the from table and column a custom name can be specified with the name option.
It would make sense to use this property instead of id and rails allows custom primary keys but there are some gotchas.
Railsで modelにforeign keyを指定した場合に orderメソッドを使ってソートしたいです 下記のようにユーザーと部署テーブルがあり ユーザーは部署に2つ所属する場合 class user activerecord base belongs to unit first foreign key.
The foreign key option lets you set the name of the foreign key directly.