Questions tagged [has-one]
385 questions
154
votes
3 answers
Rails: Using build with a has_one association in rails
In this example, I create a user with no profile, then later on create a profile for that user. I tried using build with a has_one association but that blew up. The only way I see this working is using has_many. The user is supposed to only have at…
espinet
- 1,703
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79
votes
3 answers
Difference between has_one and belongs_to in Rails?
I am trying to understand has_one relationship in RoR.
Let's say I have two models - Person and Cell:
class Person < ActiveRecord::Base
has_one :cell
end
class Cell < ActiveRecord::Base
belongs_to :person
end
Can I just use has_one :person…
Moon
- 22,195
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24
votes
4 answers
grails hasOne vs direct member variable
Let's say I have a grails domain class that looks like
class Person {
Address address
}
I could also declare it as
class Person {
static hasOne = [address:Address]
}
The second way would move the foreign key to the Address table rather than…
Jeff Storey
- 56,312
- 72
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- 406
23
votes
2 answers
Rails nested has_one: cannot delete existing record
I'm trying to update nested question_output attributes in a 'question' model. A question has_one question_output. If there are no existing question_outputs in the database, everything works fine. But if the record already has a question_output, I…
PlankTon
- 12,443
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- 153
19
votes
2 answers
Rails: Create association if none is found to avoid nil errors
I have an application where my users can have a set of preferences. Both are stored as ActiveRecord-models as follows:
class User < AR::Base
has_one :preference_set
end
class PreferenceSet < AR::Base
belongs_to :user
end
I can now access the…
Mattias
- 193
- 1
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- 4
14
votes
5 answers
where condition with HasOne laravel
In login model I have implement relation with picture table
function picture () {
return $this->hasOne('App\Picture');
}
Now I want data where Picture.picture_status = 1 and User.user_status = 1
Login::with('picture')->where('picture_status',…
Harman
- 1,703
- 5
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- 40
12
votes
2 answers
Can has_one association be used when the model has one or zero instances of another model?
RailsGuides says:
http://guides.rubyonrails.org/association_basics.html
A has_many "association indicates that each instance of the model has zero or more instances of another model."
"A has_one association also sets up a one-to-one connection with…
user2725109
- 2,286
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- 46
11
votes
2 answers
Rails 3 has_one routing
I have two classes:
class User < ActiveRecord::Base
:has_one :foo
end
class Foo < ActiveRecord::Base
:belongs_to :user
end
The Foo is optional.
I created the following routing:
resources :users do
resources :foo
end
Which results in the…
craig
- 25,664
- 27
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- 205
10
votes
4 answers
Rails: has_one and belongs_to with presence validation on both foreign keys
I have an application with a users table and a user_profiles table. A user has_one user profile and a user profile belongs_to a user.
I want to make sure that the association scenario is always true, so I've put a validation for the presence of both…
Robert Audi
- 8,019
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9
votes
2 answers
In Rails, what is the difference using "has_many with belongs_to" vs "has_many with has_one"?
For example, in
class Student < ActiveRecord::Base
has_many :awards
end
class Awards < ActiveRecord::Base
belongs_to :student
end
the above should be the correct usage, but what if we use
class Student < ActiveRecord::Base
has_many…
nonopolarity
- 146,324
- 131
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- 740
9
votes
1 answer
Rails determine if association is has_one or has_many
Wondering if there is an easy way to determine dynamically if a model's association is a "has_one" or "has_many" relationship (i.e. is this an association to one object or many).
I'm using MongoMapper, so I am able to check if a class klass has an…
pariser
- 275
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- 10
9
votes
1 answer
Zero or one association in ActiveRecord
I am writing a Ruby on Rails application that has two models - User and Farm. A User is considered a farmer if their farmer field is set to true. However, there is no seperate class for farmers.
A User may have either one farm, or none at all. (I…
Aaltan Ahmad
- 141
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8
votes
3 answers
ruby on rails has_one association with unique
Hey I have a model foo that has_one :bar. And bar belongs_to :foo. I was wondering if there is a way to augment the has_one such that no two bars can belong to the same foo. I looked at the documentation for has_one and it seems like there is no…
deruse
- 2,851
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8
votes
4 answers
Best way to specify a default record for a has_many relationship in rails
I have Accounts and AccountAddressess. An account can have many AccountAddressess and I would like to specify one as the "default_account_address", so in the Account table, I have a column named "default_account_address_id". Here is the current…
Shagymoe
- 1,296
- 1
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8
votes
2 answers
RoR: has_one "or the other"? (Or, polymorphism without the inheritance.)
Hey all, I have something of an interesting requirement for my project. I need a has_one relationship where it is either one class or the other, but without inheritance. I could get away with inheritance if it is the only way, but the two…
Robert K
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