Ruby on Rails

On 26 March 2012 11:19, bingo bob <lists@ruby-forum.com> wrote:
> Colin Law wrote in post #1052973:
>> On 23 March 2012 16:48, bingo bob <lists@ruby-forum.com> wrote:
>>>
>>>>> Freddy (2, male)
>>>>
>>>> What if one of the Freddys is female? Maybe not likely with this name
>>>> but there are names that can be both.
>>>
>>> True - in my system the user simply designates a name as either M or F,
>>> gender is an attribute of name...quite possible to have the same name as
>>> both M and F and rightly so, actually current schema attached in case it
>>> helps.
>>
>> I think you would be better to have a join table, user_names maybe.
>> Then have
>> User
>> has_many :user_names
>> has_many :names, :through => :user_names
>>
>> UserName
>> belongs_to :user
>> belongs_to :name
>>
>> Name
>> has_many :user_names
>> has_many :users, :through => :user_names
>>
>> Have given and gender in names and the position in user_names
>>
>> I think that might help a lot.  For example to find how many users
>> have a name you can then just use @name.users.count.
>>
>> Colin
>
> Thanks for taking the time Colin, that's thought provoking in several
> ways.
>
> 1) You're right the ability to do simply @name.users.count would be
> excellent.
>
> 2) I've got an existing schema in place and am wondering if I can
> migrate to this new schema (perhaps with some additional migrations and
> rake tasks) or maybe that's a very tricky task.

Never be afraid to refactor if you find a better way to do something.
You should always have good automated test coverage so you can be
reasonably confident that you have not broken anything. I hope you
are using a version control system (such as git) so that if you decide
it is all a disaster then you can easily go back to where you were.

>
> 3) Linked to two, think carefully about the data model before starting
> out.

Don't spend /too/ much time thinking about it beforehand, you can
always refactor it later.

>
> I don't think what I've got is wrong it's just that @name.users.count
> and the like seems like the most elegant way to handle the queries I
> need to be doing.

In that case what you have got is wrong in the sense that something
else would be better.

>
> The idea of a join table scares me a bit but I get where you're coming
> from.

If you are going to get anywhere with Rails then you will need to know
how to use join tables so take this opportunity to learn.

Colin

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