Rails Thinks Field is Nil When it Shouldn't - ruby-on-rails

I have an Event model which has a start_date and end_date. I have a simple validation to make sure that the end_date is after the start_date, however, the validation keeps failing when a date field is not changed, but another field is updated. In such cases, it interprets the fields are nil, even though in the trace, the record shows the proper field values.
# error
undefined method `<' for nil:NilClass
app/models/event.rb:32:in `end_after_start'
# validation in event.rb
attr_accessible :end_date, :start_date
validate :end_after_start
def end_after_start
if end_date < start_date
errors.add(:end_date, "must be after the start date")
end
end
# request parameters in trace
{"utf8"=>"✓",
"_method"=>"put",
"authenticity_token"=>"DD6rVimJxAJclO4IKfv69Txn8XkJZ4IpHZhh+cHOpg4=",
"event"=>{"name"=>"Birthday",
"start_date"=>"05/16/2013",
"end_date"=>"05/31/2013",
"commit"=>"Submit",
"id"=>"5"}
# _form
<%= f.text_field :start_date, :value => (#event.start_date.strftime("%m/%d/%Y") if #event.start_date.present?) %>
<%= f.text_field :end_date, :value => (#event.end_date.strftime("%m/%d/%Y") if #event.end_date.present?) %>
Even though I see the end_date and start_date populated in the trace parameters, if I add put start_date (or end_date) in the end_after_start validation, it prints as nil to the console.

The problem is your form is formatting your dates as "mm/dd/yyyy" and the fields are being submitted to your application in that format as strings.
There is no implicit conversion of a string in that format to a DateTime so your start_date and end_date are ending up nil.

Try to set:
attr_accessor :end_date, :start_date
If you do not have the columns in your database, you will need that.
attr_accessible allows parameters in a mass association.
attr_accessor sets a getter and a setter.
If you have those columns you could try prepending self..

I got this to work by installing the american_date gem. It allows for my date field to be displayed as MM/DD/YYYY and validates and saves my date correctly.

Related

Rails: Mapping a Date from form parameters into ActiveModel object

I have a filter-class which includes ActiveModel and consists of two dates:
class MealFilter
include ActiveModel::Model
attribute :day_from, Date
attribute :day_to, Date
end
That model is rendered into a form as following:
<%= form_for(#filter) do |f| %>
<div class="form-group form-group--date">
<%= f.label :day_from %>
<%= f.date_select :day_from %>
</div>
<div class="form-group form-group--date">
<%= f.label :day_to %>
<%= f.date_select :day_to %>
</div>
<% end %>
The problem is now, when the form gets submitted, it sends this parameters to the controller:
{"utf8"=>"✓", "meal_filter"=>{"day_from(1i)"=>"2016", "day_from(2i)"=>"1", "day_from(3i)"=>"29", "day_to(1i)"=>"2016", "day_to(2i)"=>"1", "day_to(3i)"=>"30"}, "commit"=>"Filter"}
I extract the values via Controller parameters:
def meal_filter_params
if params.has_key? :meal_filter
params.require(:meal_filter).permit(:day_from, :day_to)
end
end
if I now assign the params[:meal_filter] to my MealFilter class with #filter = MealFilter.new(meal_filter_params), my date fields are not updated correctly. It seams that the 1i, 2i, 3i parts are not correctly assigned to the dates.
However, this works fine if used an ActiveRecord class.
Do I miss some include? Does anyone know, where this magic mapping is implemented if not in ActiveModel::Model?
I came across this issue while upgrading an app from Rails 3.2 to 5.0
How I sorted it out is as follows:
For Rails 5
class MealFilter
include ActiveRecord::AttributeAssignment
attr_reader :day_from
def initialize(attributes = {})
self.attributes = attributes || {}
end
def day_from=(value)
#day_from = ActiveRecord::Type::Date.new.cast(value)
end
end
For Rails 4.2
class MealFilter
include ActiveRecord::AttributeAssignment
attr_accessor :day_from
def initialize(attributes = {})
self.attributes = attributes || {}
end
def type_for_attribute(name)
case name
when "day_from" then ActiveRecord::Type::Date.new
end
end
end
Then you can do:
attributes = { "day_from(3i)" => "1", "day_from(2i)" => "9", "day_from(1i)" => "2020" }
meal_filter = MealFilter.new(attributes)
meal_filter.day_from
# => Tue, 01 Sep 2020
Ok, found a solution.
What I needed was the MultiparameterAssignment which is actually implemented in ActiveRecord but not in ActiveModel.
As far as I can see, there is an open pull request (https://github.com/rails/rails/pull/8189) that should resolve this issue.
But in the meantime, some clever guy wrote a module that can be included into the model: https://gist.github.com/mhuggins/6c3d343fd800cf88f28e
All you need to do is to include the concern and define a class_for_attribute method that returns the class where your attribute should be mapped to - in my case Date.
You can simply access the 1i, 2i and 3i parameters from the date_select helper and combine them to make new Date in a before_validation callback:
class DateOfBirth
include ActiveModel::Model
include ActiveModel::Attributes
include ActiveModel::Validations::Callbacks
attribute :date_of_birth, :date
attribute "date_of_birth(3i)", :string
attribute "date_of_birth(2i)", :string
attribute "date_of_birth(1i)", :string
before_validation :make_a_date
validates :date_of_birth, presence: { message: "You need to enter a valid date of birth" }
def make_a_date
year = self.send("date_of_birth(1i)").to_i
month = self.send("date_of_birth(2i)").to_i
day = self.send("date_of_birth(3i)").to_i
begin # catch invalid dates, e.g. 31 Feb
self.date_of_birth = Date.new(year, month, day)
rescue ArgumentError
return
end
end
end

Understanding Rails date in form_for

I am trying to get a date from a user and send it inside an email as plain text in the following format: "07/30/2015".
In order to do that, if the output I am getting is a string, I could just do:
Date.parse("2015-07-30").strftime("%m/%d/%Y")
The problem is, I am getting a FixNum.
The issues are many:
If I try to convert to a string to parse it with Date.parse, it becomes "2001".
If I apply the code I just wrote, Date.parse... it will throw 'invalid date'.
For instance:
(2016-02-13).to_s #=> "2001"
(2016-02-13).to_date #=> NoMethodError: undefined method `to_date' for 2001:Fixnum
Date.parse("2001").strftime("%m/%d/%Y") #=> invalid date
So if I can convert 2015-07-30 into "2015-07-30", it would work:
Date.parse("2015-07-30").strftime("%m/%d/%Y") #=> "07/30/2015"
Then I tried using date_select instead of date_field, but now the message arrives with those fields empty.
Any suggestions?
Here is my form:
= form_for #contact do |f|
= f.text_field :product_name
= f.date_field :purchase_date
= f.submit
Here is my code:
<%= message.subject %>
<% #resource.mail_form_attributes.each do |attribute, value|
if attribute == "mail_subject"
next
end
%>
<%= "#{#resource.class.human_attribute_name(attribute)}: #{Date.parse(value).class == Date ? Date.parse(value).strftime("%m/%d/%Y") : value}" %>
<% end %>
My controller:
class ContactsController < ApplicationController
before_action :send_email, except: [:create]
def create
#contact = Contact.new(params[:contact])
#contact.request = request
if #contact.deliver
#thank = "Thank you for your message!"
#message = "We have received your inquiry and we'll be in touch shortly."
else
#error = "Cannot send message. Please, try again."
end
end
def contact_page
end
def product_complaint
#the_subject = "Product Complaint Form"
end
private
def send_email
#contact = Contact.new
end
end
My model:
class Contact < MailForm::Base
# all forms
attribute :mail_subject
attribute :first_name, validate: true
attribute :last_name, validate: true
# product-complaint
attribute :best_by, validate: true, allow_blank: true # date
attribute :bag_code, validate: true, allow_blank: true
attribute :purchase_date, validate: true, allow_blank: true # date
attribute :bag_opened, validate: true, allow_blank: true # date
attribute :problem_noticed, validate: true, allow_blank: true # date
# all forms
attribute :message, validate: true
attribute :nickname, captcha: true
def headers
{
content_type: "text/plain",
subject: %(#{mail_subject}),
to: "xxxxx#xxxxxxx.com",
# from: %("#{first_name.capitalize} #{last_name.capitalize}" <#{email.downcase}>)
from: "xxx#xxxxx.com"
}
end
end
(2016-02-13).to_date #=> NoMethodError: undefined method `to_date' for 2001:Fixnum
youre getting this error because you dont have quotes around the value. i.e. its not a string, its a number that is having subtraction applied to it. this is being interpreted as
2016 - 2
2014 - 13
2001.to_date
it needs to be ('2016-02-13').to_date
if youre unable to get it as a string, can you post how you're getting it from the user to begin with? (a date field ought to be sending you a string to your controller, not a series of numbers)
You're not understanding something about receiving values from forms: You can NOT receive an integer, a fixnum or anything else other than strings. So, you can't have received 2016-02-13. Instead you got "2016-02-13" or "2016", "02" or "2" and "13" depending on the form. If you're running under Rails, then it got the strings, and through its meta-data understands you want an integer (which really should probably be defined as a string), and it converts it to an integer for you.
Either way, when you write:
(2016-02-13).to_s
(2016-02-13).to_date
you're propagating that misunderstanding into your testing. This is how it MUST be written because you need to be working with strings:
require 'active_support/core_ext/string/conversions'
("2016-02-13").to_s # => "2016-02-13"
("2016-02-13").to_date # => #<Date: 2016-02-13 ((2457432j,0s,0n),+0s,2299161j)>
You can create dates without them being strings though: Ruby's Date initializer allows us to pass the year, month and day value and receive a new Date object:
year, month, day = 2001, 1, 2
date = Date.new(year, month, day) # => #<Date: 2001-01-02 ((2451912j,0s,0n),+0s,2299161j)>
date.year # => 2001
date.month # => 1
date.day # => 2
Moving on...
Parsing dates in Ruby quickly demonstrates it's not a U.S.-centric language. Americans suppose all dates of 01/01/2001 are in "MM/DD/YYYY" but that's a poor assumption because much of the rest of the world uses "DD/MM/YYYY". Not knowing that means that code written under that assumption is doing the wrong thing. Consider this:
require 'date'
date = Date.parse('01/02/2001')
date.month # => 2
date.day # => 1
Obviously something "wrong" is happening, at least for 'mericans. This is very apparent with:
date = Date.parse('01/31/2001')
# ~> -:3:in `parse': invalid date (ArgumentError)
This occurs because there is no month "31". In the previous example of '01/02/2001', that misunderstanding means the programmer thinks it should be "January 2" but the code thinks it's "February 1", and work with that. That can cause major havoc in an enterprise system, or anything dealing with financial calculations, product scheduling, shipping or anything else that works with dates.
Because the code is assuming DD/MM/YYYY format for that sort of string, the sensible things to do are:
KNOW what format your users are going to send dates in. Don't assume, ever. ASK them and make your code capable of dealing with alternates, or tell them what they MUST use and vet out their data prior to actually committing it to your system. Or, provide a GUI that forces them to pick their dates from popups and never allows them to enter it by hand.
Force the date parser to use explicit formats of dates so it can always do the right thing:
Date.strptime('01/31/2001', '%m/%d/%Y') # => #<Date: 2001-01-31 ((2451941j,0s,0n),+0s,2299161j)>
Date.strptime('31/01/2001', '%d/%m/%Y') # => #<Date: 2001-01-31 ((2451941j,0s,0n),+0s,2299161j)>
The last point is the crux of writing code: We're telling the language what to do, not subjecting ourselves, and our employers, to code that's guessing. Give code half a chance and it'll do the wrong thing, so you control it. That's why programming is hard.

How to validate start date on update?

How to validate start date on update that it should not be previous date than previously saved date.
eg:- like I have created record with start date as 07/11/2013, on update it should not before the 07/11/2013.
in view:
f.input :start_date, as: :datepicker
f.input :end_date, as: :datepicker
model:
validates :start_date, allow_nil: true, date: { after: Date.today - 1, message: 'must be today or after today' }, on: :create
validates :end_date, allow_nil: true, date: { after: :start_date, message: 'must be after start date' }
Thanks.
I can't test it right now but I think it might work:
validate :previous_start_date
def previous_start_date
old_start_date = Model.find(self.id).start_date
if(old_start_date > self.start_date)
self.errors.add(:start_date, "Can't be previous than the initial date")
end
end
At the moment of the validation, the object hasn't been saved yet, so, I believe that retrieving the object from the database will give you the previous value. With the value in hand you can compare with the current start_date and then add your custom error.
I hope it helps.
You can add attr_accessor :previous_start_date(dont forget also about attr_accessible) plus add hidden field on form. This field must have value equal to start_date from DB.
Then you can use after :previous_start_date.
Note: value previous_start_date must be set from DB, maybe better to do it in model in getter method or set in before_validation callback.

"error(s) on assignment of multiparameter attributes" date/time fields

My application has a model "Appointments" which have a start and end attribute both which are datetimes. I am trying to set the date and time parts separately from my form so I can use a separate date and time picker. I thought I should be able to do it like this. From what I ahve read rails should combine the two parts and then parse the combined field as a datetime like it usually would
The error I am getting:
2 error(s) on assignment of multiparameter attributes [error on assignment ["2013-09-16", "15:30"] to start (Missing Parameter - start(3)),error on assignment ["2013-09-16", "16:30"] to end (Missing Parameter - end(3))]
These are the request parameters:
{"utf8"=>"✓", "authenticity_token"=>"OtFaIqpHQFnnphmBmDAcannq5Q9GizwqvvwyJffG6Nk=", "appointment"=>{"patient_id"=>"1", "provider_id"=>"1", "start(1s)"=>"2013-09-16", "start(2s)"=>"15:30", "end(1s)"=>"2013-09-16", "end(2s)"=>"16:30", "status"=>"Confirmed"}, "commit"=>"Create Appointment", "action"=>"create", "controller"=>"appointments"}
My Model
class Appointment < ActiveRecord::Base
belongs_to :patient
belongs_to :practice
belongs_to :provider
validates_associated :patient, :practice, :provider
end
And the relevant part of the view: (its a simple form)
<%= f.input :"start(1s)", :as => :string, :input_html => { :class => 'date_time_picker' , :value => Date.parse(params[:start]) }%>
<%= f.input :"start(2s)", :as => :string, :input_html => { :class => 'date_time_picker' , :value => Time.parse(params[:start]).strftime('%R') }%>
<%= f.input :"end(1s)", :as => :string, :input_html => { :class => 'date_time_picker' , :value => Date.parse(params[:end]) }%>
<%= f.input :"end(2s)", :as => :string, :input_html => { :class => 'date_time_picker' , :value => Time.parse(params[:end]).strftime('%R') }%>
UPDATE:
THis is now how my model looks like, Ive been trying to do getter/setter methods but I am stuck because start-dat, start_time etc are nil in the model and the parameters aren't sent through
class Appointment < ActiveRecord::Base
belongs_to :patient
belongs_to :practice
belongs_to :provider
validates_associated :patient, :practice, :provider
before_validation :make_start, :make_end
############ Getter Methods for start/end date/time
def start_time
return start.strftime("%X") if start
end
def end_time
return self.end.strftime("%X") if self.end
end
def start_date
return start.strftime("%x") if start
end
def end_date
return self.end.strftime("%x") if self.end
end
def start_time=(time)
end
def end_time=(time)
end
def start_date=(date)
end
def end_date=(date)
end
def make_start
if defined?(start_date)
self.start = DateTime.parse( self.start_date + " " + self.start_time)
end
end
def make_end
if defined?(end_date)
self.start = DateTime.parse( end_date + " " + end_time)
end
end
end
Are you trying to emulate #date_select ? If yes, see second part of answer.
Date database typecast
If you want to assign a DateTime to database, it has to be a DateTime object. Here you use an array of strings, ["2013-09-16", "15:30"].
You can easily compute a datetime from those strings using regexps :
/(?<year>\d+)-(?<month>\d+)-(?<day>\d+)/ =~ params[ 'start(1s)' ]
/(?<hours>\d+):(?<minutes>\d+)/ =~ params[ 'start(2s)' ]
datetime = DateTime.new( year.to_i, month.to_i, day.to_i, hours.to_i, minutes.to_i )
This will store year, month, day, hours and minutes in local variables and create a new datatime based on it, which you can then assign to your model.
Yet, databases can't store ruby DateTime instances as is, so behind the hood, a conversion is made by rails when saving a date or datetime field to convert it as string. The method used is #to_s(:db), which gives, for example :
DateTime.now.to_s(:db) # => "2013-09-17 09:41:04"
Time.now.to_date.to_s(:db) # => "2013-09-17"
So you could theoretically simply join your strings to have proper date representation, but that wouldn't be a good idea, because :
that's implementation details, nothing say this date format won't change in next rails version
if you try to use the datetime after assigning it and before saving (like, in a before_save), it will be a string and not a datetime
Using active_record datetime helpers
As this would be a pain to do that all the time, rails has helpers to create and use datetime form inputs.
FormBuilder#datetime_select will take only the attribute you want and build all needed inputs :
<%= f.datetime_select :start %>
This will actually create 5 inputs, named respectively "start(1i)" (year), "start(2i)" (month), "start(3i)" (day), "start(4i)" (hours) and "start(5i)" (minutes).
If it feels familiar, it's because it's the exact data we retrieved for building a datetime in first part of this answer. When you assign a hash to a datatime field with those exact keys, it will build a datetime object using their values, like we did in first part.
The problem in your own code is that you've just provided "start(1i)" and "start(2i)". Rails doesn't understand, since you only passed it the year and month, a lot less than what is required to compute a datetime.
See How do ruby on rails multi parameter attributes *really* work (datetime_select)
According to this question, the multiparameter attribute method works for Date but not DateTime objects. In the case of a Date, you would pass year, month and day as separate values, hence the Missing Parameter - start(3), as the expected third parameter is not there.
DateTime, however, requires at least five params for instantiation DateTime.new(2013, 09, 16, 15, 30), so you cannot rely on the automated parsing in your case. You would have to split your params first and in that case, you could easily parse it yourself before saving the object using a before_filter or similar methods.
See the constructor:
http://www.ruby-doc.org/stdlib-1.9.3/libdoc/date/rdoc/DateTime.html#method-c-new
and the multiparam description:
http://apidock.com/rails/ActiveRecord/AttributeAssignment/assign_multiparameter_attributes

Rails 3 validations problem

In my form I would like users to type a date in DD/MM/YYYY format. I have validation that checks that.
The problem is that in the database it is stored in YYYY-MM-DD format, so if try just to update the is_money_paid field:
job = Job.find(params[:id])
job.update_attributes(:is_money_paid => ...)
the validation fails saying that job's date is in wrong format (YYYY-MM-DD rather than DD/MM/YYYY).
What would be an appropriate way to solve this ?
Here is the relevant code:
class Job < ActiveRecord::Base
validate :job_date_validator
end
DATE_REGEX = /\A\d{2}\/\d{2}\/\d{4}\z/
def job_date_validator
if job_date_before_type_cast.blank?
errors.add(:job_date, "^Date must be selected")
elsif job_date_before_type_cast !~ DATE_REGEX
errors.add(:job_date, "^Date must be in DD/MM/YYYY format")
end
end
is_money_paid is a boolean field.
I would change the validator to say:
validate_presence_of :job_date, :message => "must be selected"
validate :job_date_validator, :if => :job_date_changed?
Or something along those lines.
You can take out the .blank? check too.
Format it in before_validation
http://guides.rubyonrails.org/active_record_validations_callbacks.html#updating-an-object
I would suggest you to see gem validates_timeliness which is rails 3 compatible.

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