Rails schema not updating
For example, if your application includes authors and books, and each book can be assigned to exactly one author, you'd declare the book model this way: model, you would be told that there was an "uninitialized constant Book:: Authors".This is because Rails automatically infers the class name from the association name.
This object will be instantiated from the passed attributes, and the link through this object's foreign key will be set, but the associated object will method returns a new object of the associated type.
For example, if a document has many sections, and a section has many paragraphs, you may sometimes want to get a simple collection of all paragraphs in the document.
You could set that up this way: association creates a direct many-to-many connection with another model, with no intervening model.
In this case, the column definition might look like this: association.
This association indicates that each instance of the model has zero or more instances of another model.