I am using SQLite3 and I would like the following to work:
class AddNameToGoal < ActiveRecord::Migration
def change
add_column :goals, :goal_name, :text, default: goal.exercise.name
end
end
Or maybe this makes more sense as what I'm trying to do:
add_column :goals, :gname, :text, default: Goal.find(row_id).exercise.name
How do I get the above to work.
I doubt it will work as it is but that's what I want.
Specifically, The user is associated with an Exercise through the exercise_id column.
belongs_to :user
belongs_to :exercise
has_many :workouts, dependent: :destroy
(This is the model for Goal)...
I would like the user to be able to choose their own name for the Goal but I can give them the hint to name the goal after the Exercise's name and if they choose to leave it blank it will default to the exercise's name. More importantly this must happen on the SQL side so that later when I have a collection drop down which requires a name of the goal they will need a name which corresponds to the exercise.
<%= f.collection_select(:goal_id, #goals, :id,
:goal_name, :include_blank => "Please Select") %>
The Exercise Model is made in Rails to have
id, Name, other columns.
Exercise Model:
class Exercise < ActiveRecord::Base
has_one :goal
Is there a strategy by which that is possible.
Another option would be to help me find a strategy for active record so that I can do:
<%= f.collection_select(:goal_id, #goals, :id,
:goal_name, :include_blank => "Please Select") %>
with (something else to replace goal_name with Exercise.name like goal.exercise.name and goal.id and show only the ID.
Doing this when you define the column on the table is problematic. I definitely think doing it upon creation, in the model, is how you'd want to go.
You might also check out the default_value_for gem and see if it helps.
Hi so in case any body ever wants to do this:
I figured out a strategy...
This is perfect for anything that has an instance of name in terms of the user.
For example, you have something that tracks your Car and you want to give that Car by default the name which comes from that Car's Make_and_Model (model) in Rails.
Naturally when someone says they have a new "Honda Accord" then they get to have that name, but if they ever want to change it to "Lucy" because her name is Lucy and you better treat her with the respect she deserves!, then this gives you the option to do that.
You do not want to change the name for that whole Make&Model you only want to change the name for that specific car.make_and_model which belongs_to User.
If you are wanting something to have a name that defaults to another name but allows the user to change that. Do that on the model level... by setting a before_save method inside the model... like so:
before_save :default_values
def default_values
self.goal_name = self.exercise.name if self.goal_name.nil?
end
Related
I am pretty new to Rails and I am lost right now.
I was following the blog tutorial, utilizing the information to create a different application which is kinda similar.
Well, what I want (in SQL language) is:
select planned from hourplans where area_id = 2 and time = '9:00:00'
There are 4 Models in my Application (it is basically the application from the blog tutorial put twice on the same website):
Productions (which can have multiple downtimes) [Production] --1-------N-- [Downtime]
class Production < ActiveRecord::Base
has_many :downtimes, dependent: :destroy
validates :items, presence: true
end
Production has the Attributes: Date(date), Time(time), Area(text) and Items(integer)
class Downtime < ActiveRecord::Base
belongs_to :production
end
Downtime has the Attributes Username(text), Category(text), Machine(text), Station(text), Minutes(integer) and Details(text)
Areas (which can have multiple hourplans) [Area] --1-------N-- [Hourplan]
class Area < ActiveRecord::Base
has_many :hourplans, dependent: :destroy
validates :title, presence: true
end
Area has the Attributes Title(text), Text(text)
class Hourplan < ActiveRecord::Base
belongs_to :area
end
Hourplan has the Attributes Time(time), Cycle(decimal), Minutes(integer) and Planned(integer)
So for example there is an object for the production from 9:00 to 10:00, production has a field called "area" which has the value 'area2'.
And there is also a object of Area which has the title 'Area2' which is related to an object Hourplan that has a field called 'planned' with the value of items that are planned(like 600) from 9:00 to 10:00.
How can I fetch that data into the show-page of the production from 9:00 to 10:00?
I can't get it to transfer.
I tried something like:
<% area2.hourplans.where("time = 09:00").select(:planned) %>
but that didnt work.
Then I thought I had to set the object of the model to a variable first, so I tried:
<% area = Area.find_by title: #production.area %>
But I just dont get it. I dont know whether this worked or not. But how can I get to the hourplans now? Those are related to the Areas
I also tried:
<%= Hourplan.select("planned").where("time = 9:00 AND area_id = 2") %>
and that just gave me:
#<Hourplan::ActiveRecord_Relation:0x50c23e0> and I dont know what that means, I thought I would have gotten a value out of the SQL Table, like '600'
I hope I made myself clear and understandable. If you have any questions please let me know. I would really appreciate your help, I was looking through the official guides but I can't really find what I am looking for.
You may try to replace
<%= Hourplan.select("planned").where("time = 9:00 AND area_id = 2") %>
by
<%= Hourplan.where("time = '9:00' AND area_id = 2").first.planned %>
Indeed, the where method returns a relation, which represents (roughly) the result of a SQL query. But you know that an SQL query may or may not return a single line. Generally, there are several rows returned. That's why you'll want to add first, to get only the first Hourplan object.
Note: I was overthinking things when I originally asked this question. The accepted answer is correct for the examples I gave - i.e. you can just pass :value to text_field, however I'd actually been having problems with date_select, which doesn't have a facility to override the value set.
As a result this has now been updated in Rails, so you can set :selected => a_date, and it will work as expected. This will be in Rails 4.
I have a model that can inherit its value from a parent model. It works something like this:
class User < ActiveRecord::Base
attr_accessible :field_name
belongs_to :company
def field_name
if self['field_name'].nil?
company['field_name']
else
self['field_name']
end
end
end
class Company < ActiveRecord::Base
attr_accessible :field_name
end
I then have a form to edit the User, but of course, if the User value is nil, then it populates the form with the value from Company, which is not what I want.
I would like to be able to override the value of the form field, so that if the User value is nil, then the value is empty.
Attempt 1
Ideally I'd be able to do:
<%= form_for #user do |f| %>
<%= f.text_field :field_name, #user['field_name'] %>
<% end %>
But that doesn't work, there doesn't seem to be a mechanism for providing an override value.
Attempt 2
So I thought about creating a second getter/setter:
def field_name_uninherited
self['field_name']
end
def field_name_uninherited=(value)
self['field_name']=value
end
Now I can use <%= f.text_field :field_name_uninherited %> and it works as expected - great! Except: when field_name is a date, or other type using multiparameter attributes, it results in this error:
1 error(s) on assignment of multiparameter attributes
I believe this is because it doesn't know that this is a date field, as it infers this from the database, and this field (with _uninherited suffix) is not in the database.
So I need some way to mark my additional method as the same type as the original database field.
A further note, the above examples (using field_name) are a simplified version. I'm actually using https://github.com/colinbm/inherits_values_from to handle the inheritance, but I don't think this is important to the question.
Obviously if there's a better way to accomplish the same goal, then I'm all ears.
So when it comes to displaying the value you for a user you want it to behave a bit differently?
What I'd do is use the :value option with your form field. That way you get to set the value like normal but choose what you want displayed in the form field.
<%= f.text_field :company, :value => user.field_name_uninherited %>
For what I understand, you want the user to put the field data and only if it's nil, populate that value with the parent (company) model. It seems to me before_save works perfectly, because it is called (as it name proposes) just before the save method is called on an ActiveRecord object.
Thus you can write this kind of callback:
class User < ActiveRecord::Base
attr_accessible :field_name
before_save :override_field
private
def override_field
if self.field_name.nil?
self.field_name = company.field_name
end
end
This way, you'll be only overriding the value if it's nil at the moment of saving, leaving that form field empty at the moment of creating a new element. Hope this works!
I have problem how to create form for assigning child to one of parents. My child-nodes are defined in system, i go to child (alias) and want to assign it to one of parents contacts) (or create new). How do I create such form?
class Alias < ActiveRecord::Base
belongs_to :user
belongs_to :contact
end
class Contact < ActiveRecord::Base
has_many :aliases
belongs_to :user
end
So i have couple objects of Alias and couple of Contact, but I don't want to go to Contact and there assign Alias, but go to Alias, and pickup one of Contacts from (example) select box.
There are many ways to select the association id. A select box is probably the most space efficient on a page, but sometimes radio buttons work nice if there are few possible associations.
I think something like this might suit you. This assumes you assign #contacts to something like Contact.all inside your controller.
= form_for #alias do |f|
= f.label :contact_id, "Contact"
= f.collection_select :contact_id, #contacts, :id, :full_names
This assumes you have a field called "full_names" in your contact. Put whatever field you want to show in the select box.
Creating the Contact from the Alias is more tricky, and personally I wouldn't recommend it. Here are a couple questions which explain how to do it though:
Does accepts_nested_attributes_for work with belongs_to?
Getting fields_for and accepts_nested_attributes_for to work with a belongs_to relationship
I hope that helps.
I'm trying to model this inheritance for a simple blog system
Blog has many Entries, but they may be different in their nature. I don't want to model the Blog table, my concern is about the entries:
simplest entry is an Article that has title and text
Quote, however, does not have a title and has short text
Media has a url and a comment...
etc...
What is a proper way to model this with Ruby on Rails? That is
Should I use ActiverRecord for this or switch to DataMapper?
I would like to avoid the "one big table" approach with lots of empty cells
When I split the data into Entry + PostData, QuoteData etc can I have belongs_to :entry in these Datas without having has_one ??? in the Entry class? That would be standard way to do it in sql and entry.post_data may be resolved by the entry_id in the postdata table.
EDIT: I don't want to model the Blog table, I can do that, my concern is about the entries and how would the inheritance be mapped to the table(s).
I've come across this data problem several times and have tried a few different strategies. I think the one I'm a biggest fan of, is the STI approach as mentioned by cicloon. Make sure you have a type column on your entry table.
class Blog < ActiveRecord::Base
# this is your generic association that would return all types of entries
has_many :entries
# you can also add other associations specific to each type.
# through STI, rails is aware that a media_entry is in fact an Entry
# and will do most of the work for you. These will automatically do what cicloon.
# did manually via his methods.
has_many :articles
has_many :quotes
has_many :media
end
class Entry < ActiveRecord::Base
end
class Article < Entry
has_one :article_data
end
class Quote < Entry
has_one :quote_data
end
class Media < Entry
has_one :media_data
end
class ArticleData < ActiveRecord::Base
belongs_to :article # smart enough to know this is actually an entry
end
class QuoteData < ActiveRecord::Base
belongs_to :quote
end
class MediaData < ActiveRecord::Base
belongs_to :media
end
The thing I like about this approach, is you can keep the generic Entry data in the entry model. Abstract out any of the sub-entry type data into their own data tables, and have a has_one association to them, resulting in no extra columns on your entries table. It also works very well for when you're doing your views:
app/views/articles/_article.html.erb
app/views/quotes/_quote.html.erb
app/views/media/_media.html.erb # may be medium here....
and from your views you can do either:
<%= render #blog.entries %> <!-- this will automatically render the appropriate view partial -->
or have more control:
<%= render #blog.quotes %>
<%= render #blog.articles %>
You can find a pretty generic way of generating forms as well, I usually render the generic entry fields in an entries/_form.html.erb partial. Inside that partial, I also have a
<%= form_for #entry do |f| %>
<%= render :partial => "#{f.object.class.name.tableize}/#{f.object.class.name.underscore}_form", :object => f %>
<% end %>
type render for the sub form data. The sub forms in turn can use accepts_nested_attributes_for + fields_for to get the data passed through properly.
The only pain I have with this approach, is how to handle the controllers and route helpers. Since each entry is of its own type, you'll either have to create custom controllers / routes for each type (you may want this...) or make a generic one. If you take the generic approach, two things to remember.
1) You can't set a :type field through update attributes, your controller will have to instantiate the appropriate Article.new to save it (you may use a factory here).
2) You'll have to use the becomes() method (#article.becomes(Entry)) to work with the entry as an Entry and not a subclass.
Hope this helps.
Warning, I've actually used Media as a model name in the past. In my case it resulted in a table called medias in rails 2.3.x however in rails 3, it wanted my model to be named Medium and my table media. You may have to add a custom Inflection on this naming, though I'm not sure.
You can handle this easily using ActiveRecord STI. It requires you to have a type field in your Entries table. This way you can define your models like this:
def Blog > ActiveRecord::Base
has_many :entries
def articles
entries.where('Type =', 'Article')
end
def quotes
entries.where('Type =', 'Quote')
end
def medias
entries.where('Type =', 'Media')
end
end
def Entry > ActiveRecord::Base
belongs_to :blog
end
def Article > Entry
end
def Quote > Entry
end
def Media > Entry
end
I'm still a bit of a n00b when it comes to rails, however, I do have a question as to how to go about a multi-model form.
Basically, I have an event, and the user needs to be able to register for the event and provide a credit card for charging the event to. The credit card (I won't be holding the actual data for the CC, authorize.net will, but I need to keep a token representing the card) will live with the user so they can sign up for other events in the future. So, I want the user to be able to edit this in the future, and the card isn't specific to a single event. This doesn't seem like something I'd use nested routes with, does it?
I have a feeling this is fairly simple, but I guess I'm just not entirely sure how to do it. Can I used nested models (not routes) and still update each portion independently?
If I understand your question, then yes you can. I think you mean something like this:
class User < ActiveRecord::Base
has_one :credit_card
end
If that's correct, then the first step is to add this to the User class:
class User < ActiveRecord::Base
has_one :credit_card
accepts_nested_attributes_for :credit_card
end
At this point you could just set up a "users" resource in the routes file and you could edit the credit card through a fields_for method in your edit view:
form_for #user do |f|
f.fields_for :credit_card do |ff|
ff.label :number
ff.text_field :number
end
f.submit
end
Does that help?
Since Formatting is not allowed in comments, I am making a answer for it.
Thanks #twmills for your answer,
I am also new to rails. I have a question, will it work in case where I have following relationship:
class User < ActiveRecord::Base
has_many :credit_cards, :dependent => :destroy
accepts_nested_attributes_for :credit_card
end
class CreditCards < ActiveRecord::Base
belongs_to :user
end
In above case, you can't create a CreditCard object unless you have parent user. Will f.fields_for :credit_card do |ff| also create an object of CraeditCard #user to f?
As per my understanding, this is not possible as how will be tell the view, which credit card to edit.
Secondly, On edit, this is fine but can I do something similar at the time of user creation. i.e. getting his credit card information at the time of user creation.