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I know there some object has nil? method, I want to know is there some method with nil?
There is a similar answered post here: a-concise-explanation-of-nil-v-empty-v-blank-in-ruby-on-rails
Summarizing:
If you are using rails (not just ruby) there are three methods in your toolkit: .nil?, .empty? and .blank?
Follow the link to see the good description
w.nil?
inverse of
!w.nil?
You could use present?, which acts as a sort of !blank?
you could use defined? as well
No.
1.9.3p125 :002 > Object.methods.grep(/nil/)
=> [:nil?]
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Is it possible to have JSON.parse work 2 layers deep so that a hash within a hash will get parsed as well? Is there a method for or do I have to do something like JSON.parse(JSON.parse(...)['foo'])?
JSON.parse doesn't care about your hash structure:
> str = JSON.dump({foo: {bar: {baz: :qux}}})
=> "{\"foo\":{\"bar\":{\"baz\":\"qux\"}}}"
> p = JSON.parse(str).with_indifferent_access
=> {"foo"=>{"bar"=>{"baz"=>"qux"}}}
> p[:foo][:bar][:baz]
=> "qux"
(Well, it cares if you have a malformed string, but that's something else altogether.)
So, what are you asking?
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I want to check if param key exists with a variable name and if it exists I want to use value something like params[filenamestring[-1]].
filenamestring is any array generate with split
generally we use params like params[:key] but here i have array and want to use params value with array last element like params[filenamestring[-1]]
You are looking for this:
if params.key?(filenamestring[-1])
This will check if the key exists within the params.
Edit: Something like this would add the param to an array:
my_array << params[filenamestring[-1]] if params.key?(filenamestring[-1])
Or to add it to a string or integer:
my_variable + params[filenamestring[-1]] if params.key?(filenamestring[-1])
If you are doing something else, let me know and I'll update my answer again.
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If I have a form input where someone puts 'facebook.com' or 'google.com' it turns it into a valid URL adding http:// so that rails can use it. What I want is to have a form where you input a URL and it grabs the 3 most used words at that site and shows them in a list on the results page. This list should be accessible later, so I also need to store those words with that URL
def smart_add_url_protocol
url = Url.find_by(params[:url])
unless self.url[/\Ahttp:\/\//] || self.url[/\Ahttps:\/\//]
self.url = "http://#{self.url}"
end
end
something like this.
You can use URI::HTTP#build like so:
URI::HTTP.build(host: 'facebook.com').to_s
#=> "http://facebook.com"
I recommend the Addressable gem which is somewhat smart about guessing URLs from strings:
require "addressable/uri"
Addressable::URI.heuristic_parse(some_string_with_an_url).to_s
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Closed 9 years ago.
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So I'm passing a string with the name of an activerecord model class into my method and I want to be able to call some methods on that class.
This is wrong:
def perform(body_class, body_id)
body = body_class.constantize
request = body.find(body_id)
end
Update - that actually works fine.
What error are you getting? Make sure the string is in the correct ActiveRecord format.
For example:
"Person".constantize # works
"person".constantize # does not work
To get the second one to work you should also add camelize
"person".camelize.constantize # works
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My user has the attribute:
:step1_local
:step2_local
:step3_local
...
...
:local1
:local2
:local3
I would like to change an attribute value based on another set of attributes on the same model. I would like to do some processing mapping on user, say:
def magic (user)
user.local(1..3) = process(user.step(1..3)_local)
end
The code above of course does not work (example). I am not sure how to do it dynamically without going through each attributes individually. I want to map processing one to another. Any ideas?
You can use Object#public_send and method, like this:
def magic(user)
(1..3).each do |n|
user.public_send("local#{n}=", process(user.read_attribute("step#{n}_local")))
end
end