class User
has_one :settings
class Settings
belongs_to :user
I want to do something like
#user_with_no_settings = User.where(:settings => nil)
But this returns an empty relation.
How do I find all users which don't have a settings related to them? (So I will find them and create them)
Most importantly, your association is incorrect;
Change it to:
class User
has_one :setting
class Settings
belongs_to :user
The Class name is plural but the association has_one is always singular. So you can't use :settings for has_one as oppose to has_many which is always plural.
Use this:
User.where("id not in (select user_id from settings)")
The above query will give all the users which don't have a settings associated to them.
Okay. In your situation you may need some TRY this code.
User.where('id NOT IN (?)', User.joins(:settings).pluck('settings.user_id'))
But, you need to follow Rails Convention.
Change settings to setting.
Related
I'm working on a Rails 3.0.x application (actually it's Hobo 1.3.x but that's not material to this question). Among the models, there are GraphPanes, GraphLabels, and LabelSets. A GraphPane can have GraphLabels and LabelSets. GraphLabels can belong to GraphPanes or LabelSets, but not both. So if a GraphLabel belongs to a LabelSet, I'd like to keep it from being associated to a GraphPane.
I am trying to enforce that with this code in the GraphPane model:
has_many :graph_labels, :conditions => 'label_set_id = NULL'
However, I'm still able to associate GraphLabels with not-null label_set_id with GraphPanes. Why? How can I stop this?
This question is superficially similar, but my relationship isn't polymorphic, so the nominal solution there doesn't help me.
The functionality of :conditions on has_many is to filter the results that are passed back via the graph_labels, not to protect objects from being added to the association.
If you add a graph_label with no label_set_id, the association will build, but if you then ask for graph_pane.graph_labels, it will not return that non-condition-matching graph_label.
The has_many/belongs_to relationship is saved on the belongs_to model, graph_label, and so the parent/has_many/graph_pane does not stop the graph_label from writing whatever it wants to its graph_pane_id attribute. This delegation of responsibility is correct, although frustrating, I agree.
Now, as for how to stop this, I'm not sure. It sounds like you need some sort of validation on the graph_label object, something along the lines of not allowing a graph_pane_id to be set on a graph_label if that graph_label's label_set_id is nil. Since the has_many/belongs_to relationship is saved on the graph_label, you should write the validation on the graph_label. That way, the graph_label will not be able to be saved with a new graph_panel_id unless it fulfills the condition.
Thoughts? Questions?
Reference:
has_many
Alternate Solution
I've reread your question and I think want you want here is a polymorphic association.
def GraphPane < ActiveRecord::Base
has_many :label_sets
has_many :graph_labels, as: :parent
end
def LabelSet < ActiveRecord::Base
belongs_to :graph_pane
has_many :graph_labels, as: :parent
end
def GraphLabel < ActiveRecord::Base
belongs_to :parent, polymorphic: true
end
That way, a GraphLabel can only have a single parent, which is what your “spec” above requires. Is there any reason not to implement the relations in this way?
i've been searching through similar questions but i still don't get how implement this relationship. I have of course three models :
class Recetum < ActiveRecord::Base
attr_accessible :name, :desc, :duration, :prep, :photo, :topic_id
has_many :manifests
has_many :ingredients, :through => :manifests
end
class Ingredient < ActiveRecord::Base
attr_accessible :kcal, :name, :use, :unity
has_many :manifests
has_many :recetum, :through => :manifests
end
class Manifest < ActiveRecord::Base
attr_accessible :ingredient_id, :quantity, :receta_id
belongs_to :recetum
accepts_nested_attributes_for :ingredient
belongs_to :ingredient
end
Recetum would be a recipe (typo when scaffolding), this recipe may have one or more ingredients (already on the db). So when i create a new Recetum, i need the new recetum to be created and one record inserted in manifest for each ingredient entered by the user.
I would need some help now with views and controllers, how do i create the form for recetum with fields for the ingredients and more important what do i have to modify recetum controller.
Any suggestions or help would be very much appreciated as this part is crucial for my project, thanks in advance.
You have a couple options, and mainly they depend on what you want to do in your view. Do you want to display a set number of max_ingredients or do you want it to be completely dynamic? The dynamic case looks better for the user for sure, but it does make for some more complicated code.
Here is a good RailsCast which explains how to do it dynamically via JavaScript:
http://railscasts.com/episodes/74-complex-forms-part-2
Unfortunately, not everyone runs with JavaScript enabled so you may want to consider doing it the static way.
Firstly, I don't think you need accepts_nested_attributes_for in your Manifest model. However, I do think you need it in your Recetum model. If you're going the static route, you'll probably want to set a reject_if option too.
accepts_nested_attributes_for :manifests, reject_if: :all_blank
Once you do this, you'll need to add manifests_attributes to your attr_accessible.
With the static route, you'll need to prebuild some of the manifests. In your new controller you'll want something like this:
max_ingredients.times do
#recetum.manifests.build
end
In your edit and the error paths of your create and update, you may want:
(max_ingredients - #recetum.manifests.count).times do
#recetum.manifests.build
end
Finally, your view will need some way to set the ingredient. I'll assume a select box for now.
f.fields_for :manifests do |mf|
mf.label :ingredient_id, "Ingredient"
mf.collection_select :ingredient_id, Ingredient.all, :id, :name
You'll want to add some sort of formatting through a list or table probably.
Hopefully, that's enough to get you started.
I am working with a Rails polymorphic inheritance configuration - I have the following setup:
User < ActiveRecord::Base
belongs_to :rolable, :polymorphic => true
Student < ActiveRecord::Base
has_one :user, :as => :rolable
accepts_nested_attributes_for :user
Teacher < ActiveRecord::Base
has_one :user, :as => :rolable
accepts_nested_attributes_for :user
I want to be able to capture email address for teachers and a username for students (who won't typically have an email address). I defined those as attributes of the User model, but now I'm stuck when I try to do validations for Student and Teacher. I didn't define them in their respective models because I'm using Devise and there will be other user types. Abstracting what is currently type to a Role pattern isn't a good fit for my particular scenario either.
Since username and email are properties of User what I basically want to do is check if the rolable_type field from the polymorphic relationship is type student and if so, make username required and email not, but in the new method that property isn't set. However Rails 'knows' this is a Student, so it feels like there's some way to check the instance type. The closest link I've found to what I'm shooting for is the third comment to the accepted answer in this question: How to apply different validation rule according to polymorphic association type (Rails)?, but I'm having trouble getting the method_missing syntax correct as I'm not experienced with metaprogramming. Am I on the right track with this? Or is there a simpler way? Or should I move the properties to the polymorphic models instead?
I have a simple question, but can't seem to find any solution, though I have found things that are similar, but just not exactly what I am looking for.
I have an application where a User has many Assets through the class UserAsset. I want to be able to do current_user.user_assets , but I only want to return records that have an Asset with a specified field value of "active".
This post is similar but I need to use the main model not the join model as a filter.
class UserAsset < ActiveRecord::Base
belongs_to :asset
belongs_to :user
end
class Asset < ActiveRecord::Base
has_many :user_assets
has_many :users, :through => :user_assets
end
class User < ActiveRecord::Base
has_many :user_assets
has_many :assets, :through => :user_assets
end
I tried setting the default scope on Asset, and also some conditions on the has many (user_assets) relationship, but rails is failing to consider the join on the Assets table. ie Unknown column 'asset.live' in 'where clause'. Trying to achieve the following:
#active_user_assets = current_user.user_assets #only where assets.active = true
So how do I use conditions or scopes to achieve this? I need the user_asset object because it contains info about the relationship that is relevant.
Thanks in advance!
You want current_user.assets, then your scopes should work.
Oh, but you want the user_assets. Hmm. I think you need the :include clause to find() but where to put it, I can't be arsed to think of right now.
Perhaps
current_user.user_assets.find(:all, :include => :assets).where('asset.live=?', true)
(I'm not on Rails 3 yet, so that's going to be mangled)
Are you using :through when you really want a HABTM?
Given I have an Artifact model and a User model: I would like to define two Artifact fields, opened_by and assigned_to, who values are User ids and inherit all of the proper association methods.
What is the proper belongs_to or has_one or has_many options I should set?
The goal is to be able to reference the user's name through the statement hld.assiged_to.name where hld is an artifact.
Thanks for the help. I've gotten myself confused with terminology with all of the reading i've done on the problem.
The following is what I determined was correct.
class Artifact < ActiveRecord::Base
belongs_to :project
belongs_to :opened_by, :class_name => 'User'
belongs_to :assigned_to, :class_name
=> 'User'
The first argument in the belongs_to specifies the field to reference. The second indicates the model/class to use as the reference.