Best Practice About Empty Belongs_To Association

Best practice about empty belongs_to association

I think it is absolutely normal approach.

You can just leave house_id with null value in database for the models which don't belong to other.

Custom searching a belongs_to assocation is empty

<%= search.input :cities, collection: City.all.order(name: :asc), as: :select, label: "City" %>

One of the reasons the above code didn't work is,

City.all.order(name: :asc) return a ActiveRecord::Relation object, but a collection searches for an array or range.

Collections can be arrays or ranges. from the collection documentation

Another point from that documentaion is,

when a :collection is given the :select input will be rendered by default, so we don't need to pass the as: :select

So, change the input to

<%= search.input :cities, collection: City.uniq.pluck(:name).sort,label: "City" %>

Association belongs_to :through

There is has_many :through in Rails. You can check out the Rails guide to see how to use it.

Delete a belongsTo Association

why not using Foreign Keys in the database and select on DELETE CASCADE and let the database do the work...

[Based on the comment] if you the Address is attached to other models that you dont want to delete, you can set those FK to ON DELETE RESTRICT and the building wont be deleted.

And if you need something more complex you can add the beforeDelete() callback in your model, there's an example in the doc

Good Luck

How do I make my belongs_to field optional?

It used to be that you could just leave the value as nil and Rails was perfectly happy. However this was changed in Rails 5.

If you want the belongs_to to be optional, you simply have to pass optional: true:

belongs_to :grading_rubric, optional: true

You can find more info about it here

cakephp mapping $belongsTo association to a non primary key

hmm this might not be the correct way, but i already had some similar problems and i corrected it by doing something like:

'conditions' => array(' `RentalLineitem`.`i_num` = `Inventory`.`i_num`'),

hope this helps,

Good Luck

Correct way to build multiple belongs_to association

You can accomplish what you need any number of ways, all of which being valid.

# Option 1
Content.create(data_book: DataBook.create(whatever_params), client: Client.create(whatever_params))

# Option 2
data_book = DataBook.create(whatever_params)
client = Client.create(whatever_params)
content = Content.create(data_book: data_book, client: client)

# Option 3
content = Content.new
content.data_book = DataBook.find(id)
content.client = Client.find(id)
content.save

# Options 4
content = Content.new
data_book = content.build_data_book(whatever_params)
client = content.build_client(whatever_params)
content.save

# Etc. etc. etc.
...

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