Rails first_or_create! creating null values in database table - mysql

Question

I'm using first_or_create to populate a table with a list of email subscribers (called members). The code is as follows:
def community_members=(members)
self.members = members.split(",").map do |member|
Member.where(email: member.strip, community_id: self.id).first_or_create! unless member.strip == nil
end
end
Everything works fine, except that when I add additional emails to the same community, the table turns the "community_id" column for all previous rows to NULL.
Here's the server log:
Member Load (0.2ms) SELECT "members".* FROM "members" WHERE "members"."email" = $1 AND "members"."community_id" = $2 ORDER BY "members"."id" ASC LIMIT 1 [["email", "lisa#holy.com"], ["community_id", 1]]
SQL (0.3ms) INSERT INTO "members" ("email", "community_id", "created_at", "updated_at") VALUES ($1, $2, $3, $4) RETURNING "id" [["email", "lisa#holy.com"], ["community_id", 1], ["created_at", "2015-04-30 16:14:25.930012"], ["updated_at", "2015-04-30 16:14:25.930012"]]
Member Load (0.2ms) SELECT "members".* FROM "members" WHERE "members"."community_id" = $1 [["community_id", 1]]
SQL (0.4ms) UPDATE "members" SET "community_id" = NULL WHERE "members"."community_id" = $1 AND "members"."id" = 30 [["community_id", 1]]
(0.3ms) COMMIT
The first "Member" load does exactly what it's supposed to do. But for some reason it always ends with the second Member load that goes in and sets all "community_id" fields to NULL.
Right now I call :community_member from a form on a community page:
<%= form_for(#community) do |f| %>
<%= f.text_area :community_members, class:"form-control input-lg", placeholder:"Please add your list of comma separated member email addresses here" %>
<%= f.submit "Save", class: "btn btn-lg btn-green btn-block pad-top" %>
<% end %>
Seems like I'm missing something obvious here. Any ideas? Thank you.

Answer 1

You're going to want to find by the unique attribute, email, and create by community name, I think.
If that's the case, you'll have to do something like:
Member.where(email: member.strip).first_or_create(community: self) unless...
If you have records with non-unique emails, you'll have to redesign your associations.
class Subscriber
#this should have the email attribute
has_many :community_subscribers
has_many :communities, through: :community_subscribers
end
class CommunitySubscriber
#this is a 'bridge' table
belongs_to :subscriber
belongs_to :community
end
class Community
has_many :community_subscribers
has_may :subscribers, through: :community_subscribers
#I suggest new method and arg names
#Using self will keep the query within the scope of the community you are working on
#This also allows for creation of Subscriber records if you insist placing that here
#are you sure you want to map instead of just iterating the split list of emails?
def new_subscribers(emails)
emails.split(",").map do |email|
clean_email = email.strip
subscriber = Subscriber.where(email: clean_email).find_or_create unless clean_email.blank?
self.community_subscribers.where(subscriber: subscriber).first_or_create unless subscriber.blank?
end
end
end
Docs:
http://apidock.com/rails/v3.2.1/ActiveRecord/Relation/first_or_create
http://guides.rubyonrails.org/v3.2.13/active_record_querying.html#first_or_create