I would like to make a string to become an attribute:
Model:
Author
attr_accessible :book1, book2, book3 etc...
I would like to retrieve 20 books in a lesser command
def do_something
self.book1
self.book2
self.book3
....
end
This is a solution I came up with but how can I make the string become an attribute so I could retrieve the data.
def do_something
count = 0
10.times do
self."book#{count += 1}"
end
end
This will work:
def do_something
count = 0
10.times do
self.send("book#{count += 1}")
end
end
Also try this, it's simpler and it should work as well: self[:book1] or self['book1']
BTW this is weird design. Consider using array of books instead:
attr_accessible :books
...
self.books.each { |book| puts book }
self.books[0] # etc.
You can use eval.
10.times do
eval("self.book#{count} = count}")
end
Related
I have a model/table with a json column in it as follows
t.json :options, default: {}
The column can contain many keys within it, something like this
options = {"details" : {key1: "Value1", key2: "Value2"}}
I want to set and get these values easily. So i have made getters and setters for the same.
def key1
options['details']&.[]('key1')
end
def key1=(value)
options['details'] ||= {}
options['details']['key1'] ||=0
options['details']['key1'] += value
end
But this just adds lines to my code, and it does not scale when more details are added. Can you please suggest a clean and neat way of doing this?
Use dynamic method creation:
options['details'].default_proc = ->(_,_) {{}}
ALLOWED_KEYS = %i[key1 key2 key3]
ALLOWED_KEYS.each do |key|
define_method key do
options['details'][key] if options['details'].key?(key)
end
define_method "#{key}=" do |value|
(options['details'][key] ||= 0) += value
end
end
You can just pass the key as a parameter as well right?
def get_key key=:key1
options['details']&.[](key)
end
def set_key= value, key=:key1
options['details'] ||= {}
options['details'][key] ||=0
options['details'][key] += value
end
Simple & Short
Depending on re-usability you can choose different options. The short option is to simply define the methods using a loop in combination with #define_method.
class SomeModel < ApplicationRecord
option_accessors = ['key1', 'key2']
option_accessors.map(&:to_s).each do |accessor_name|
# ^ in case you provide symbols in option_accessors
# this can be left out if know this is not the case
define_method accessor_name do
options.dig('details', accessor_name)
end
define_method "#{accessor_name}=" do |value|
details = options['details'] ||= {}
details[accessor_name] ||= 0
details[accessor_name] += value
end
end
end
Writing a Module
Alternatively you could write a module that provide the above as helpers. A simple module could look something like this:
# app/model_helpers/option_details_attribute_accessors.rb
module OptionDetailsAttributeAccessors
def option_details_attr_reader(*accessors)
accessors.map(&:to_s).each do |accessor|
define_method accessor do
options.dig('details', accessor)
end
end
end
def option_details_attr_writer(*accessors)
accessors.map(&:to_s).each do |accessor|
define_method "#{accessor}=" do |value|
details = options['details'] ||= {}
details[accessor] ||= 0
details[accessor] += value
end
end
end
def option_details_attr_accessor(*accessors)
option_details_attr_reader(*accessors)
option_details_attr_writer(*accessors)
end
end
Now you can simply extend your class with these helpers and easily add readers/writers.
class SomeModel < ApplicationRecord
extend OptionDetailsAttributeAccessors
option_details_attr_accessor :key1, :key2
end
If anything is unclear simply ask away in the comments.
for one of my views I want to include a search field with jqueries typeahead function.
The array should contain all the attribute values of a client.
The array for the query is generated the following way:
#clients = []
Client.each do |client|
#clients << client.attributes.values.join(' ')
end
Is this approach performant enough for a dataset of about 3000 entries?
Or is there a better and faster solution?
Thanks in advance.
Cheers,
Patrick
Update
One user mentioned to implement it like this:
#clients = Client.map do |client|
client.attributes.values.join(' ')
end
This is another way to do it. But a benchmark reveals that this is no improvement in performance.
This leaves me with the question: Maybe there is a more performant way, but speaking about a maxium of 3000 records - does it really matter?
You could use .map:
#clients = Client.map do |client|
client.attributes.values.join(' ')
end
Even if ActiveRecord models would implement the map method (which they don't i believe), the two solutions suggested by the OP and #xdazz are time- and memory-complexity-wise equivalent. This can be observed with this simple benchmark:
require 'fruity'
# Dummy client class
class Client < Struct.new(:first_name, :last_name, :position, :company)
class << self
include Enumerable
def each(&block)
5000.times do
yield Client.new('Firstname', 'Lastname', 'CEO', 'Company Inc.')
end
end
end
alias_method :attributes, :to_h
end
compare do
schnika do
clients = []
Client.each do |client|
clients << client.attributes.values.join(' ')
end
nil
end
xdazz do
clients = Client.map do |client|
client.attributes.values.join(' ')
end
nil
end
end
Which will output
schnika is similar to xdazz
Also, when you look at the implementation of map (synonymous to collect), it becomes clear that really nothing else happens than in the OP's method:
static VALUE
rb_ary_collect(VALUE ary)
{
long i;
VALUE collect;
RETURN_ENUMERATOR(ary, 0, 0);
collect = rb_ary_new2(RARRAY_LEN(ary));
for (i = 0; i < RARRAY_LEN(ary); i++) {
rb_ary_push(collect, rb_yield(RARRAY_PTR(ary)[i]));
}
return collect;
}
This translates to:
class Array
def collect
collect = []
self.each do |el|
collect << yield(el)
end
collect
end
end
You probably don't need to retrieve all the attributes (for example 'updated_at'), so the following may be faster:
#clients = Client.select([:name, :email, :id]).map do |client|
client.attributes.values.join(' ')
end
Added the id in case you need to link to the client.
I wrote a small benchmarking Class for testing my code doing development. At the moment I have to add the Class to the beginning and end of every method. Is it posible to prepend, append on the fly, so that I don't have to clutter my code?
class ApplicationController
before_filter :init_perf
after_filter :write_perf_results_to_log!
def init_perf
#perf ||= Perf.new
end
def write_perf_results_to_log!
#perf.results
end
end
class Products < ApplicationsController
def foo
#perf.log(__methond__.to_s)
caculation = 5 *4
#perf.write!
end
def bar
#perf.log(__methond__.to_s)
caculation = 1 / 5
#perf.write!
end
end
This is the Perf class. It is located in the services folder.
class Perf
def initialize
#results = []
end
def log(note)
#start = Time.now
#note = note
end
def write!
if #results.find {|h| h[:note] == #note } # Update :sec method exists in results
#results.select { |h| h["note"] == #note; h[":sec"] = (Time.now - #start).round(3) }
else # Add new Hash to results
#results << { :note => #note, :sec => (Time.now - #start).round(3) }
end
end
def results
content = "
PERFORMANCE STATISTICS!
"
#results.each do |r|
content += r[:note] + " " + r[:sec].to_s + "
"
end
content += "
"
Rails.logger.info content
end
end
In general computing terms what you want to do is called code instrumentation. There are several ways to accomplish this, however here's one (crude) example using some metaprogramming:
First define a new method that we will use for injecting our instrumentation code:
class ApplicationController
def self.instrument_methods(*methods)
methods.each { |m|
# Rename original method
self.send(:alias_method, "#{m}_orig", m)
# Redefine old method with instrumentation code added
define_method m do
puts "Perf log #{m}"
self.send "#{m}_orig"
puts "Perf write"
end
}
end
end
How to use it:
class Product < ApplicationController
def foo
puts "Foo"
end
def bar
puts "Bar"
end
# This has to be called last, once the original methods are defined
instrument_methods :foo, :bar
end
Then:
p = Product.new
p.foo
p.bar
Will output:
Perf log foo
Foo
Perf write
Perf log bar
Bar
Perf write
Here are some other ways to instrument ruby code and measure performance:
http://ruby-prof.rubyforge.org/
http://www.igvita.com/2009/06/13/profiling-ruby-with-googles-perftools/
There is better solution.
class ApplicationController
def self.inherited(klass)
def klass.method_added(name)
return if #_not_new
#_not_new = true
original = "original #{name}"
alias_method original, name
define_method(name) do |*args, &block|
puts "==> called #{name} with args: #{args.inspect}"
result = send original, *args, &block
puts "<== result is #{result}"
result
end
#_not_new = false
end
end
end
class Product < ApplicationController
def meth(a1, a2)
a1 + a2
end
end
product = Product.new
puts product.meth(2,3)
And the result:
==> called meth with args: [2, 3]
<== result is 5
5
The source & explanation are here: http://pragprog.com/screencasts/v-dtrubyom/the-ruby-object-model-and-metaprogramming. I recommend to spend not a big money to get this course.
I'm the author of aspector gem. Thanks to dimuch for mentioning it.
I've come up with a solution using aspector. Here are the high level steps:
Create an aspect as a subclass of Aspector::Base
Inside the aspect, define advices (before/after/around are the primary types of advices)
Apply the aspect on target class (or module/object)
The full code can be found in this gist. Please feel free to let me know if you have questions or the solution doesn't do what you intend to.
class PerfAspect < Aspector::Base
around options[:action_methods] do |proxy|
#perf ||= Perf.new
proxy.call
#perf.results
end
around options[:other_methods], :method_arg => true do |method, proxy, *args, &block|
#perf.log(method)
result = proxy.call *args, &block
#perf.write!
result
end
end
action_methods = [:action]
other_methods = Products.instance_methods(false) - action_methods
PerfAspect.apply(Products, :action_methods => action_methods, :other_methods => other_methods)
Guess aspector gem can help. It's not well documented but has useful examples.
I have a User model with Profit field. Profit field is a DECIMAL (11,0) type. I have a masked input on the form which allows user to input something like $1,000. I want to format that value and remove everything except numbers from it so i will have 1000 saved. Here is what i have so far:
class User < ActiveRecord::Base
before_save :format_values
private
def format_values
self.profit.to_s.delete!('^0-9') unless self.profit.nil?
end
end
But it keeps saving 0 in database. Looks like it is converting it to decimal before my formatting function.
Try this:
def profit=(new_profit)
self[:profit] = new_profit.gsub(/[^0-9]/, '')
end
First of all, this:
def format_values
self.profit.to_s.delete!('^0-9') unless self.profit.nil?
end
is pretty much the same as this:
def format_values
return if(self.profit.nil?)
p = self.profit
s = p.to_s
s.delete!('^0-9')
end
So there's no reason to expect your format_values method to have any effect whatsoever on self.profit.
You could of course change format_values to assign the processed string to self.profit but that won't help because your cleansing logic is in the wrong place and it will be executed after '$1,000' has been turned into a zero.
When you assign a value to a property, ActiveRecord will apply some type conversions along the way. What happens when you try to convert '$1,000' to a number? You get zero of course. You can watch this happening if you play around in the console:
> a = M.find(id)
> puts a.some_number
11
> a.some_number = 'pancakes'
=> "pancakes"
> puts a.some_number
0
> a.some_number = '$1,000'
=> "1,000"
> puts a.some_number
0
> a.some_number = '1000'
=> "1000"
> puts a.some_number
1000
So, your data cleanup has to take place before the data goes into the model instance because as soon as AR gets its hands on the value, your '$1,000' will become 0 and all is lost. I'd put the logic in the controller, the controller's job is to mediate between the outside world and the models and data formatting and mangling certainly counts as mediation. So you could have something like this in your controller:
def some_controller
fix_numbers_in(:profit)
# assign from params as usual...
end
private
def fix_numbers_in(*which)
which.select { |p| params.has_key?(p) }.each do |p|
params[p] = params[p].gsub(/\D/, '') # Or whatever works for you
end
end
Then everything would be clean before ActiveRecord gets its grubby little hands on your data and makes a mess of things.
You could do similar things by overriding the profit= method in your model but that's really not the model's job.
class User < ActiveRecord::Base
before_save :format_values
private
def format_values
self.profit = profit.to_s.gsub(/\D/,'') if profit
end
end
def format_values
self.profit.to_d!
end
I recommend you to write custom setter for this particular instance variable #profit:
class User
attr_accessor :profit
def profit= value
#profit = value.gsub(/\D/,'')
end
end
u = User.new
u.profit = "$1,000"
p u.profit # => "1000"
I would suggest using the rails helper of number with precision. Below is some code.
Generic Example:
number_with_precision(111.2345, :precision => 1, :significant => true) # => 100
Rails code Example:
def profit=(new_profit)
number_with_precision(self[:profit], :precision => 1, :significant => true)
end
What's the best Ruby/Rails way to allow users to use decimals or commas when entering a number into a form? In other words, I would like the user be able to enter 2,000.99 and not get 2.00 in my database.
Is there a best practice for this?
Does gsub work with floats or bigintegers? Or does rails automatically cut the number off at the , when entering floats or ints into a form? I tried using self.price.gsub(",", "") but get "undefined method `gsub' for 8:Fixnum" where 8 is whatever number I entered in the form.
I had a similar problem trying to use localized content inside forms. Localizing output is relatively simple using ActionView::Helpers::NumberHelper built-in methods, but parsing localized input it is not supported by ActiveRecord.
This is my solution, please, tell me if I'm doing anything wrong. It seems to me too simple to be the right solution. Thanks! :)
First of all, let's add a method to String.
class String
def to_delocalized_decimal
delimiter = I18n::t('number.format.delimiter')
separator = I18n::t('number.format.separator')
self.gsub(/[#{delimiter}#{separator}]/, delimiter => '', separator => '.')
end
end
Then let's add a class method to ActiveRecord::Base
class ActiveRecord::Base
def self.attr_localized(*fields)
fields.each do |field|
define_method("#{field}=") do |value|
self[field] = value.is_a?(String) ? value.to_delocalized_decimal : value
end
end
end
end
Finally, let's declare what fields should have an input localized.
class Article < ActiveRecord::Base
attr_localized :price
end
Now, in your form you can enter "1.936,27" and ActiveRecord will not raise errors on invalid number, because it becomes 1936.27.
Here's some code I copied from Greg Brown (author of Ruby Best Practices) a few years back. In your model, you identify which items are "humanized".
class LineItem < ActiveRecord::Base
humanized_integer_accessor :quantity
humanized_money_accessor :price
end
In your view templates, you need to reference the humanized fields:
= form_for #line_item do |f|
Price:
= f.text_field :price_humanized
This is driven by the following:
class ActiveRecord::Base
def self.humanized_integer_accessor(*fields)
fields.each do |f|
define_method("#{f}_humanized") do
val = read_attribute(f)
val ? val.to_i.with_commas : nil
end
define_method("#{f}_humanized=") do |e|
write_attribute(f,e.to_s.delete(","))
end
end
end
def self.humanized_float_accessor(*fields)
fields.each do |f|
define_method("#{f}_humanized") do
val = read_attribute(f)
val ? val.to_f.with_commas : nil
end
define_method("#{f}_humanized=") do |e|
write_attribute(f,e.to_s.delete(","))
end
end
end
def self.humanized_money_accessor(*fields)
fields.each do |f|
define_method("#{f}_humanized") do
val = read_attribute(f)
val ? ("$" + val.to_f.with_commas) : nil
end
define_method("#{f}_humanized=") do |e|
write_attribute(f,e.to_s.delete(",$"))
end
end
end
end
You can try stripping out the commas before_validation or before_save
Oops, you want to do that on the text field before it gets converted. You can use a virtual attribute:
def price=(price)
price = price.gsub(",", "")
self[:price] = price # or perhaps price.to_f
end
Take a look at the i18n_alchemy gem for date & number parsing and localization.
I18nAlchemy aims to handle date, time and number parsing, based on current I18n locale format. The main idea is to have ORMs, such as ActiveRecord for now, to automatically accept dates/numbers given in the current locale format, and return these values localized as well.
I have written following code in my project. This solved all of my problems.
config/initializers/decimal_with_comma.rb
# frozen_string_literal: true
module ActiveRecord
module Type
class Decimal
private
alias_method :cast_value_without_comma_separator, :cast_value
def cast_value(value)
value = value.gsub(',', '') if value.is_a?(::String)
cast_value_without_comma_separator(value)
end
end
class Float
private
alias_method :cast_value_without_comma_separator, :cast_value
def cast_value(value)
value = value.gsub(',', '') if value.is_a?(::String)
cast_value_without_comma_separator(value)
end
end
class Integer
private
alias_method :cast_value_without_comma_separator, :cast_value
def cast_value(value)
value = value.gsub(',', '') if value.is_a?(::String)
cast_value_without_comma_separator(value)
end
end
end
end
module ActiveModel
module Validations
class NumericalityValidator
protected
def parse_raw_value_as_a_number(raw_value)
raw_value = raw_value.gsub(',', '') if raw_value.is_a?(::String)
Kernel.Float(raw_value) if raw_value !~ /\A0[xX]/
end
end
end
end
I was unable to implement the earlier def price=(price) virtual attribute suggestion because the method seems to call itself recursively.
I ended up removing the comma from the attributes hash, since as you suspect ActiveRecord seems to truncate input with commas that gets slotted into DECIMAL fields.
In my model:
before_validation :remove_comma
def remove_comma
#attributes["current_balance"].gsub!(',', '') # current_balance here corresponds to the text field input in the form view
logger.debug "WAS COMMA REMOVED? ==> #{self.current_balance}"
end
Here's something simple that makes sure that number input is read correctly. The output will still be with a point instead of a comma. That's not beautiful, but at least not critical in some cases.
It requires one method call in the controller where you want to enable the comma delimiter. Maybe not perfect in terms of MVC but pretty simple, e.g.:
class ProductsController < ApplicationController
def create
# correct the comma separation:
allow_comma(params[:product][:gross_price])
#product = Product.new(params[:product])
if #product.save
redirect_to #product, :notice => 'Product was successfully created.'
else
render :action => "new"
end
end
end
The idea is to modify the parameter string, e.g.:
class ApplicationController < ActionController::Base
def allow_comma(number_string)
number_string.sub!(".", "").sub!(",", ".")
end
end
You can try this:
def price=(val)
val = val.gsub(',', '')
super
end