I have controller with action new, and I want it to create ActiveRecord::Base descendant object, and write it into database (without showing it to user).
def new
active_order = current_user.orders.find {|o| o.status > 0 }
active_order = Order.new if active_order.nil?
(...)
end
Order.new creates local object, but my question is -- how to make Rails to fill it with default values and write to database?
You can write an unsaved ActiveRecord object instance to the database with the save method:
active_order = Order.new if active_order.nil?
active_order.save
It won't fill in the columns automatically, however. If you want to populate it with default values you can do this before calling save:
active_order = Order.new if active_order.nil?
active_order.field_name = "foo"
active_order.save
Or you can pass it in when you call new:
active_order = Order.new(:field_name => "foo") if active_order.nil?
active_order.save
If you want to do something fancier, you can have Rails automatically populate fields when you save by adding something like this to the model:
before_validation_on_create :set_default_values
def set_default_values
field_name = "foo" if field_name.blank?
end
you can use Order.Create(...) which will create a new object and persist it in the database (assuming Order is a child of ActiveBase of course)
Related
I created a class method that is called when a new object is created and copied from an old existing object. However, I only want to copy some of the values. Is there some sort of Ruby shorthand I can use to clean this up? It's not entirely necessary, just curious to know if something like this exists?
Here is the method I want to DRY up:
def set_message_settings_from_existing existing
self.can_message = existing.can_message
self.current_format = existing.current_format
self.send_initial_message = existing.send_initial_message
self.send_alert = existing.send_alert
self.location = existing.location
end
Obviously this works perfectly fine, but to me looks a little ugly. Is there any way to clean this up? If I wanted to copy over every value that would be easy enough, but because I only want to copy these 5 (out of 20 something) values, I decided to do it this way.
def set_message_settings_from_existing(existing)
[:can_message, :current_format, :send_initial_message, :send_alert, :location].each do |attribute|
self.send("#{attribute}=", existing.send(attribute))
end
end
Or
def set_message_settings_from_existing(existing)
self.attributes = existing.attributes.slice('can_message', 'current_format', 'send_initial_message', 'send_alert', 'location')
end
a hash might be cleaner:
def set_message_settings_from_existing existing
fields = {
can_message: existing.can_message,
current_format: existing.current_format,
send_initial_message: existing.send_initial_message,
send_alert: existing.send_alert,
location: existing.location
}
self.attributes = fields
end
you can take this further by only selecting the attributes you want:
def set_message_settings_from_existing existing
fields = existing.attributes.slice(
:can_message,
:current_format,
:send_initial_message,
:send_alert,
:location
)
self.attributes = fields
end
at this point you could also have these fields defined somewhere, eg:
SUB_SET_OF_FIELDS = [:can_message, :current_format, :send_initial_message, :send_alert, :location]
and use that for your filter instance.attributes.slice(SUB_SET_OF_FIELDS)
I have a form with checkboxes that get passed as an array "list_person_ids" on form submit. My models are "Occurance" which has an n:m relationship with "ListPerson" through the Model "Person". "list_person_ids" are saved in Person with the Occurance id and the ListPerson id.
I want to append one or more values to the array before this gets saved. The reason I need to do this is because the user can also add a new value in ListPerson using a textbox with the name "person_name".
def create
#occurance = Occurance.new(occurance_params)
add_person_id(#occurance)
...
# save
end
def add_person_id(object)
if params[:person_check] == '1'
object.list_person_ids.push( ListPerson.find_or_create_by(person: params[:person_name]).id )
end
end
def occurance_params
params.require(:occurance).permit(:person_check, :person_name, dim_person_ids: [])
end
find_or_create_by is successful, but nothing gets pushed to the array "list_person_ids". There is also no error message. Do I have to give permission somewhere to append this array? Please let me know if some information is missing.
on your model you can do something like below:
....
before_create :create_lists
private
def create_lists
ListPerson.find_or_create_by(list_person_ids: person_name.id)
end
I would like to store each value from an array.
For example the form sends me this data:
"attendance"=>{"event_id"=>"6", "member_id"=>["16", "28", "26"]}
I'd like the database to store the data as:
INSERT INTO "attendances" ("event_id", "member_id") VALUES ("6", "16")
INSERT INTO "attendances" ("event_id", "member_id") VALUES ("6", "28")
INSERT INTO "attendances" ("event_id", "member_id") VALUES ("6", "26")
I've tried to use the usual way of inserting data in Rails, but it failed because the member_ids didn't get passed (I've tried to print the member_ids after the Attendance.new(attendance_params)):
def create
#attendance = Attendance.new(attendance_params)
# puts #attendance[:event_id]
# puts #attendance[:member_id] -> Nothing showed up here.
if #attendance.save
flash[:success] = "Successfully created"
redirect_to new_attendance_path
else
#error_msg = #attendance.errors.full_messages
flash[:error] = #error_msg # Prints ["Member must exist"]
redirect_to new_attendance_path
end
end
I've also tried creating a new function in the model to change the Attendance.new but it'll return
NoMethodError - undefined method `new_each' for #<Class:0x000000000d1e7280>: app/controllers/attendances_controller.rb:17:in `create'
This is my current model:
class Attendance < ApplicationRecord
belongs_to :event
belongs_to :member
# def new_each(attendance)
# attendance_event = attenance[:event_id]
# attendance_members = attendance[:member_id]
# I tried to iterate and save each data here.
# end
end
So, how do I save each value from an array input (from the form) and save it to database?
Any answers and comment will be very appreciated.
You are trying to add attendance in bulk, For that you can do 2 things,
use gem bulk_insert, it's very easy to use here is the link https://github.com/jamis/bulk_insert
you need to iterate through all the members and events from params and create a record for each. though it's a very dirty way.
sample code would be like this. you can modify it as per your need.
errors = {}
attendance_params[:member_id].each do |member_id|
attendence = Attendence.new(event_id:attendance_params[:event_id], member_id: member_id)
errors[member_id] = "Could not save attendance, error =
attendance.errors.full_messages" unless
attendence.save
end
Goal: dynamically update another Model's properties (Tracker) from Controller (cards_controller.rb), when cards_controller is running the def update action.
Error I receive : NameError in CardsController#update, and it calls out the 2nd last line in the
def update_tracker(card_attribute) :
updated_array = #tracker.instance_variable_get("#{string_tracker_column}")[Time.zone.now, #card.(eval(card_attribute.to_s))]
Perceived problem: I have everything working except that I don't know the appropriate way to 'call' the attribute of Tracker correctly, when using dynamic attributes.
The attribute of the Tracker is an array (using PG as db works fine), I want to
figure out what property has been changed (works)
read the corresponding property array from Tracker's model, and make a local var from it. (works I think, )
push() a new array to the local var. This new array contains the datetime (of now) and, a string (with the value of the updated string of the Card) (works)
updated the Tracker with the correct attribute.
With the following code from the cards_controller.rb
it's the if #card.deck.tracked in the update method that makes the process start
cards_controller.rb
...
def update
#card = Card.find(params[:id])
if #card.deck.tracked
detect_changes
end
if #card.update_attributes(card_params)
if #card.deck.tracked
prop_changed?
end
flash[:success] = "Card info updated."
respond_to do |format|
format.html { render 'show' }
end
else
render 'edit'
end
end
...
private
def detect_changes
#changed = []
#changed << :front if #card.front != params[:card][:front]
#changed << :hint if #card.hint != params[:card][:hint]
#changed << :back if #card.back != params[:card][:back]
end
def prop_changed?
#changed.each do |check|
#changed.include? check
puts "Following property has been changed : #{check}"
update_tracker(check)
end
end
def update_tracker(card_attribute)
tracker_attribute = case card_attribute
when :front; :front_changed
when :back; :back_changed
when :hint; :hint_changed
end
string_tracker_column = tracker_attribute.to_s
#tracker ||= Tracker.find_by(card_id: #card.id)
updated_array = #tracker.instance_variable_get("#{string_tracker_column}")[Time.zone.now, #card.(eval(card_attribute.to_s))]
#tracker.update_attribute(tracker_attribute, updated_array)
end
Edit: For clarity here's the app/models/tracker.rb:
class Tracker < ActiveRecord::Base
belongs_to :card
end
Your use of instance_variable_get has been corrected, however this approach is destined to fail because ActiveRecord column values aren't stored as individual instance variables.
You can use
#tracker[string_column_changed]
#card[card_attribute]
To retrieve attribute values by name. If you want to get an association, use public_send. The latter is also useful if there is some accessor wrapping the column value (eg carrierwave)
From your error it seem your issue is this:
#tracker.instance_variable_get("#{string_tracker_column}")
evaluates to this after string interpolation:
#tracker.instance_variable_get("front_changed")
which is incorrect use of instance_variable_get. It needs an # prepended:
#tracker.instance_variable_get("#front_changed")
Seems like using instance_variable_get is unnecessary, though, if you set attr_reader :front_changed on the Tracker model.
I'm trying to initialize an object, but I don't want to create the object to the database until the user has click saved. I've gotten this to work with the parent object only, but I can't seem to get my child objects to associate to the parent because I don't have an id yet for the parent object. What am I doing wrong in the code below? Thanks.
def new
# Build a new report object with the default type of "draft" and assign it to the player
report_options = { player_id: #player.id,
author_id: current_user.id,
position: #player.position,
type: "draft",
submitted: false }
#report = Report.new(report_options)
#skills.where('disabled = (?)',FALSE).each do |skill|
# On the line below I get an evaluation record with a proper skill id,
# but report_id is `nil` because I'm guessing the report hasn't been
# created yet. Is there a way to reserve an id for it without actually
# committing the record to the database until the user saves the record?
#report.evaluations.build(skill_id: skill.id)
end
end
The model of evaluations is not quite clear to me, but basically if you do something like
#report.evaluations.build
#skills.where('disabled = (?)', FALSE).each do |skill|
#report.evaluations << Evaluation.new(skill_id: skill.id)
end
it will add objects to evaluations without saving and won't require the report.id to exist at the moment of adding.