Support belongs_to custom method name

[c910335]

Example:

class Article < Granite::ORM::Base
  # ...
  # `#author` and `#author=` with `field author_id : Int64`
  belongs_to author : User
end

Or both this feature and custom id in #142

class Article < Granite::ORM::Base
  # ...
  # `#author` and `#author=` with `field author_id : String`
  belongs_to author : User,  author_id : String
end

This is very useful because article.author is much more readable than article.user, and an article may need to belong to more than one kind of user, for example, author and approver.

[robacarp]

It looks like decl is a pattern that is already used in this file, but what does it stand for? It seems like it means foreign_key? Can we call it something more descriptive?

[robacarp]

One minor comment, but I like this improvement and could make use of it immediately. Thanks!

[c910335]

@robacarp
I've renamed decl to foreign_key.
Thus the more readable syntax has shown.

  belongs_to author : User, foreign_key: author_id : String

And I think this syntax should be recommended.

[conradwt]

@robacarp Is it possible to use belongs_to author : User and have the foreign key inferred to be id within the users table? At this time, I'm getting the following error message:

$ amber db seed
Error in db/seeds.cr:1: while requiring "../config/application.cr"

require "../config/application.cr"
^

in config/application.cr:4: while requiring "../src/models/**"

require "../src/models/**"
^

in src/models/friendship.cr:6: macro didn't expand to a valid program, it expanded to:

================================================================================
--------------------------------------------------------------------------------
   1.     belongs_to friend : Person, friend : Person_id : Int64
   2.   
--------------------------------------------------------------------------------
Syntax error in expanded macro: belongs_to:1: unexpected token: :

    belongs_to friend : Person, friend : Person_id : Int64
                                                   ^

================================================================================

  belongs_to friend : Person
  ^~~~~~~~~~

02:10:49 Database   | (INFO) Seeded database

Can someone direct me to the actual documentation for its usage? Also, I guess part of the confusion is that there exists granite and granite_orm packages. Should one be using granite here?

[Blacksmoke16]

@conradwt You should be using granite. granite_orm is the legacy version.