I'm working with a large image array, so i've packed it. To access the pixels in the array i've implemented two methods.
def get_p(a)
data=a.unpack('S9s')
end
def put_p(array,index_a,value)
index=index_a[0]
k=array.unpack('S9s')
k[index]=value
k.pack('S9s')
end
It works, but i wondered if there was a more elegant way to do this. Makes my code look different than my standard array functions.
If get_p(image_data[i][j+1])[BLOB]==0
vs
if image_data[i][j+1][BLOB]==0
Also, don't know if anyone cares, but unpack doesn't seem to be documented anywhere, i was lucky to find a reference here, but it took some time.
You could craete a class like:
class PackedArray
def initialize(array)
#packed_array = array.pack('S9s')
end
def [](key)
data = #packed_array.unpack('S9s')
data[key]
end
def []=(key, val)
k = #packed_array.unpack('S9s')
k[key]=val
#packed_array = k.pack('S9s')
end
end
Then, fill your image_data[i][j] with an instance of this class. E.g.
for i in [0..image_data.size]
for j in [0..image_data[i].size]
image_data[i][j] = new PackedArray(image_data[i][j])
end
end
And finally you can simply use:
if image_data[i][j+1][BLOB] == 0
Without needing of packing/unpacking manually.
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'm using Rails 4 and have an Article model that has answer, side_effects, and benefits as attributes.
I am trying to create a before_save method that automatically looks at the side effects and benefits and creates links corresponding to another article on the site.
Instead of writing two virtually identical methods, one for side effects and one for benefits, I would like to use the same method and check to assure the attribute does not equal answer.
So far I have something like this:
before_save :link_to_article
private
def link_to_article
self.attributes.each do |key, value|
unless key == "answer"
linked_attrs = []
self.key.split(';').each do |i|
a = Article.where('lower(specific) = ?', i.downcase.strip).first
if a && a.approved?
linked_attrs.push("<a href='/questions/#{a.slug}' target=_blank>#{i.strip}</a>")
else
linked_attrs.push(i.strip)
end
end
self.key = linked_attrs.join('; ')
end
end
end
but chaining on the key like that gives me an undefined method 'key'.
How can I go about interpolating in the attribute?
in this bit: self.key you are asking for it to literally call a method called key, but what you want, is to call the method-name that is stored in the variable key.
you can use: self.send(key) instead, but it can be a little dangerous.
If somebody hacks up a new form on their browser to send you the attribute called delete! you don't want it accidentally called using send, so it might be better to use read_attribute and write_attribute.
Example below:
def link_to_article
self.attributes.each do |key, value|
unless key == "answer"
linked_attrs = []
self.read_attribute(key).split(';').each do |i|
a = Article.where('lower(specific) = ?', i.downcase.strip).first
if a && a.approved?
linked_attrs.push("<a href='/questions/#{a.slug}' target=_blank>#{i.strip}</a>")
else
linked_attrs.push(i.strip)
end
end
self.write_attribute(key, linked_attrs.join('; '))
end
end
end
I'd also recommend using strong attributes in the controller to make sure you're only permitting the allowed set of attributes.
OLD (before I knew this was to be used on all attributes)
That said... why do you go through every single attribute and only do something if the attribute is called answer? why not just not bother with going through the attributes and look directly at answer?
eg:
def link_to_article
linked_attrs = []
self.answer.split(';').each do |i|
a = Article.where('lower(specific) = ?', i.downcase.strip).first
if a && a.approved?
linked_attrs.push("<a href='/questions/#{a.slug}' target=_blank>#{i.strip}</a>")
else
linked_attrs.push(i.strip)
end
end
self.answer = linked_attrs.join('; ')
end
Need a little help over here :-)
I'm trying to extend the Order class using a decorator, but I get an error back, even when I use the exactly same code from source. For example:
order_decorator.rb (the method is exactly like the source, I'm just using a decorator)
Spree::Order.class_eval do
def update_from_params(params, permitted_params, request_env = {})
success = false
#updating_params = params
run_callbacks :updating_from_params do
attributes = #updating_params[:order] ? #updating_params[:order].permit(permitted_params).delete_if { |k,v| v.nil? } : {}
# Set existing card after setting permitted parameters because
# rails would slice parameters containg ruby objects, apparently
existing_card_id = #updating_params[:order] ? #updating_params[:order][:existing_card] : nil
if existing_card_id.present?
credit_card = CreditCard.find existing_card_id
if credit_card.user_id != self.user_id || credit_card.user_id.blank?
raise Core::GatewayError.new Spree.t(:invalid_credit_card)
end
credit_card.verification_value = params[:cvc_confirm] if params[:cvc_confirm].present?
attributes[:payments_attributes].first[:source] = credit_card
attributes[:payments_attributes].first[:payment_method_id] = credit_card.payment_method_id
attributes[:payments_attributes].first.delete :source_attributes
end
if attributes[:payments_attributes]
attributes[:payments_attributes].first[:request_env] = request_env
end
success = self.update_attributes(attributes)
set_shipments_cost if self.shipments.any?
end
#updating_params = nil
success
end
end
When I run this code, spree never finds #updating_params[:order][:existing_card], even when I select an existing card. Because of that, I can never complete the transaction using a pre-existent card and bogus gateway(gives me empty blanks errors instead).
I tried to bind the method in order_decorator.rb using pry and noticed that the [:existing_card] is actuality at #updating_params' level and not at #updating_params[:order]'s level.
When I delete the decorator, the original code just works fine.
Could somebody explain to me what is wrong with my code?
Thanks,
The method you want to redefine is not really the method of the Order class. It is the method that are mixed by Checkout module within the Order class.
You can see it here: https://github.com/spree/spree/blob/master/core/app/models/spree/order/checkout.rb
Try to do what you want this way:
Create file app/models/spree/order/checkout.rb with code
Spree::Order::Checkout.class_eval do
def self.included(klass)
super
klass.class_eval do
def update_from_params(params, permitted_params, request_env = {})
...
...
...
end
end
end
end
I'm kind of a newbie in some areas of ruby and rails. So I I'm writing a class to read excel depending on the extension and return the row in a each routine. Something like this:
class ExcelRead
(dependencies)
def initialize(path, sheet_n = 0)
type = File.extname(path)
if type == JitExcelRead::XLS
Spreadsheet.client_encoding = 'UTF-8'
book = Spreadsheet.open path
book_sheet = book.worksheet sheet_n
elsif type == JitExcelRead::XLSX
book = Creek::Book.new path
book_sheet = book.sheets[sheet_n]
end
#book = book
#book_sheet = book_sheet
#book_rows = book_sheet.rows
#path = path
#type = type
end
end
So this means that I call on my application
xls = ExcelRead.new(uploaded_file.filename_path)
and everything runs smooth. I have the objects I need at my disposal. My problem now is how to iterate through them. I thought that adding a method to may class like this
def each
binding.pry
end
and calling it normally on my app like so
xls.book_rows.each do |row|
end
would make me enter that code, but not really...
help?
If you added a each method to your ExcelRead class, and you create an instance of this class called xls, then you have to access it using xls.each, not xls.book_rows.each.
Using the former, you are calling the each method from the Enumerator, as book_rows is a collection.
I can only guess that you want a custom way to iterate your book_row, so i think something like this should be what you are trying to achieve:
def iterate
self.book_rows.each do |br|
# do stuff
end
end
And you call it like:
xls.iterate
But this is only a wild guess.
I have a number of these in my controller:
def ups
#ups ||= Shipper::Ups.new(
ENV['UPS_ACCESS_KEY'],
ENV['UPS_PASSWORD'],
ENV['UPS_USERNAME'],
ENV['UPS_ACCOUNT']
)
end
And then I have this block that gets called:
def type(number, carrier)
case carrier.slug
when 'ups'
number_details = ups.track(number)
when 'fedex'
number_details = fedex.track(number)
when 'usps'
number_details = usps.track(number)
end
return number_details
end
But seems I could refactor that quite a bit if I could take the carrier.slug and prepend it to the lines like ups.track(number).
Is there a way to do that?
you can use send to do this but before that we need to make sure that you have the right carrier slug
if %w[ups fedex usps].include?(carrier.slug)
send(carrier.slug).track(number)
end