I have the following in an initialize method on my model:
#home_phone = contact_hash.fetch('HomePhone')
However, sometimes I need this instead:
#home_phone = contact_hash.fetch('number')
Also, sometimes neither of those will be true and I will need the home_phone attribute to be empty.
How can I write this out without creating a big loop like so:
if contact_hash.has_key?('HomePhone')
#home_phone = contact_hash.fetch('HomePhone')
elsif contact_hash.has_key?('number')
#home_phone = contact_hash.fetch('number')
else
#home_phone = ""
end
You could try
#home_phone = contact_hash.fetch('HomePhone', contact_hash.fetch('number', ""))
or better
#home_phone = contact_hash['HomePhone'] || contact_hash['number'] || ""
contact_hash.values_at('HomePhone','number','home_phone').compact.first
Edit:
My first solution did not really give the answer asked for. Here is a modified version, although I think in the case of only 3 options the solution given by #knut is better.
contact_hash.values_at('HomePhone','number').push('').compact.first
def doit(h, *args)
args.each {|a| return h[a] if h[a]}
""
end
contact_hash = {'Almost HomePhone'=>1, 'number'=>7}
doit(contact_hash, 'HomePhone', 'number') # => 7
You could use values_at I suppose:
#home_phone = contact_hash.values_at('HomePhone', 'number').find(&:present?).to_s
That isn't exactly shorter but it wouldn't be convenient if you had the keys in an array:
try_these = %w[HomePhone number]
#home_phone = contact_hash.values_at(*try_these).find(&:present?).to_s
You could also wrap that up in a utility method somewhere or patch it into Hash.
Related
I recently solved this problem, but felt there is a simpler way to do it. I looked into inject, step, and map, but couldn't figure out how to implement them into this code. I want to use fewer lines of code than I am now. I'm new to ruby so if the answer is simple I'd love to add it to my toolbag. Thank you in advance.
goal: accept a sentence string as an arg, and return the sentence with words alternating between uppercase and lowercase
def alternating_case(str)
newstr = []
words = str.split
words.each.with_index do |word, i|
if i.even?
newstr << word.upcase
else
newstr << word.downcase
end
end
newstr.join(" ")
end
You could reduce the number of lines in the each_with_index block by using a ternary conditional (true/false ? value_if_true : value_if_false):
words.each.with_index do |word, i|
newstr << i.even? ? word.upcase : word.downcase
end
As for a different way altogether, you could iterate over the initial string, letter-by-letter, and then change the method when you hit a space:
def alternating_case(str)
#downcase = true
new_str = str.map { |letter| set_case(letter)}
end
def set_case(letter)
#downcase != #downcase if letter == ' '
return #downcase ? letter.downcase : letter.upcase
end
We can achieve this by using ruby's Array#cycle.
Array#cycle returns an Enumerator object which calls block for each element of enum repeatedly n times or forever if none or nil is given.
cycle_enum = [:upcase, :downcase].cycle
#=> #<Enumerator: [:upcase, :downcase]:cycle>
5.times.map { cycle_enum.next }
#=> [:upcase, :downcase, :upcase, :downcase, :upcase]
Now, using the above we can write it as following:
word = "dummyword"
cycle_enum = [:upcase, :downcase].cycle
word.chars.map { |c| c.public_send(cycle_enum.next) }.join("")
#=> "DuMmYwOrD"
Note: If you are new to ruby, you may not be familiar with public_send or Enumberable module. You can use the following references.
Enumberable#cycle
#send & #public_send
I have the following code:
some_array = [] # Sometimes is filled, in this case it isn't
new_array = some_array || ['default', 'array', 'values']
Now, the || is not triggered, because [] != nil
Of course it can be solved by doing:
new_array = some_array
new_array = ['default', 'array', 'values'] if new_array.blank?
But I remember there is a function that does this in a single line, like:
[].filled_arr_or_nil # nil
['something'].filled_arr_or_nil # ['something']
I wasn't able to find the answer using a search engine, but StackOverflow gave me the answer with a similar question, but then about strings:
Converting an empty string to nil in place?
The solution is to use presence
Only available within Rails.
You can use something like this
some_array = []
new_array = some_array.empty? ? ['default', 'array', 'values'] : some_array
This is just a conditional statement that uses empty? to check if some_array contains any elements and then returns the desired output
I have:
s = "like_so__case"
camelize gives this:
s.camelize # => "LikeSoCase"
I'm looking for conversion up to a double underscore __ to get:
"LikeSo__case"
How can I camelize only up to a certain part of a string?
The simplest option is to gsub part of your string.
'like_so__case'.gsub(/(.*?)(__.*)/) { "#{$1.camelize}#{$2}" }
#=> "LikeSo__case"
UPDATE
Cleaner and faster way arising from comments.
'like_so__case__h'.sub(/(.*?)(?=__)/, &:camelize)
#=> "LikeSo__case__h"
s = "like_so__case"
=> "like_so__case"
s.split('__', 2).tap { |s| s[0] = s[0].camelize }.join('__')
=> "LikeSo__case"
You of course could wrap it in string method
For getting this LikeSo__case, we can do like:
s="like_so__case"
s.split('__').tap { |s| s[0] = s[0].camelize }.join('__')
Your description on the demand is not so clear.
From your excepted result, I understand it as 'camelize a part of string until a pattern'. I should note one thing first that camelize is not part of Ruby's standard library of class String. ActiveSupport::Inflector provides it.
So if you want to just camelize each part divided by a pattern, use str.split('_').map(&:capitalize).join('_'). In your case, it returns 'Like_So__Case'.
Ruby's String has another instance method named partition, which splits the string into three parts (an array):
Part before the pattern
The pattern
Part after the pattern
So str.partition('__').tap { |a| a[0] = a[0].split('_').map(&:capitalize).join }.join should be your answer in plain Ruby.
No need of relying on camelize. Simply, this:
"like_so__case"
.gsub(/_?([a-z])([a-z]*)(?=.*__)/i){$1.upcase + $2.downcase}
# => "LikeSo__case"
def camelize(s)
for i in 0..s.size-2 do
if s[i] == "_" and s[i+1] == "_"
next
elsif s[i] == "_" and s[i+1] != "_" and s[i-1] != "_"
s[i+1] = s[i+1].upcase
s[i] = ""
else
next
end
end
return s
end
Use this method to solve your problem
s = "like_so__case"
i = s.index('__')
#=> 7
s.tap { |s| s[0,i] = s[0,i].camelize }
#=> LikeSo__case
The last line could be replaced by two lines:
s[0,i] = s[0,i].camelize
s
If the original string is not to be mutated write
s.dup.tap { |s| s[0,i] = s[0,i].camelize }
I need to form a hash dynamically after checking the existence of the values. I always run into this case and form the hash as follows, but I find this very ugly, and wondered if their is a tricky or a prettier way to do this:
Here is how I am forming it:
args = {}
args[:pagination_token] = params[:pagination_token] if params[:pagination_token]
args[:sort_by] = params[:sort_by] if params[:sort_by]
args[:sort_direction] = params[:sort_direction] if params[:sort_direction]
args[:pagination_direction] = params[:pagination_direction] if params[:pagination_direction]
args[:limit] = params[:limit] if params[:limit]
users_list, next_pagination_token, previous_pagination_token = current_application.paginated_users(args)
A better way?
You can use slice like so:
args = params.slice(:pagination_token, :sort_by, :sort_direction, :pagination_direction, :limit)
Edit:
Since the question's subject says "in Ruby", and the above method will work only if your have included ActiveSupport. Which in fact will work in this case as OP is using Rails. For those who wants to do it in Ruby can do:
valid_params = [:pagination_token, :sort_by, :sort_direction, :pagination_direction, :limit]
args = params.select{ |k| valid_params.include? k }
Use ActiveSupport's Hash#slice:
args = params.slice(:pagination_token, :sort_by, :sort_direction, :pagination_direction, :limit)
Here is one more way it can be done:
h = {
pagination_token: 100,
sort_by: 200,
# sort_direction: 300,
pagination_direction: 400,
limit: 500,
some_other_value: 500,
}
keys = [:pagination_token, :sort_by, :sort_direction]
p [keys, h.values_at(*keys)].transpose.to_h.reject {|_,v| v.nil?}
#=> {:pagination_token=>100, :sort_by=>200}
I am working on a script that is supposed to be writing a list of items to a hash, but for some reason its only placing the last item in the loop in the hash... I have been working on this script all day, so I am pretty sure its something I am just missing.
Here is the script
#mr = MediaRating.where("user_id = ?", session['user_credentials_id'])
#mr.each do |rating|
#m = Media.where("id = ?", rating.media_id)
#m.each do |m|
s = Profile.find_by_subscriber_id(m.subscriber_id)
#h_lang = Language.find_by_code(s.language)
#history = {m.title => #h_lang.english}
end
end
There are multiple records in the MediaRating table so I know it has to do something with how my loop is. Thanks in advance for the help!
Working code:
#mr = MediaRating.where("user_id = ?", session['user_credentials_id'])
#mr.each do |rating|
#m = Media.find(rating.media_id)
s = Profile.find_by_subscriber_id(#m.subscriber_id)
#h_lang = Language.find_by_code(s.language)
#history[#m.title] = #h_lang.english
end
In the last line, you are over-writing the entire #history hash instead of adding a new key/value pair to it. I'm guessing that isn't what you intended. Change this line:
#history = {m.title => #h_lang.english}
to this:
#history[m.title] = #h_lang.english