I have in the html the location variable sometimes is used with a class called "result-hood" sometimes is used with another class called "nearby"
location = result.search('span.result-hood').text[2..-2]
location2 = result.search('span.nearby').text[2..-2]
so if one of the above classes is not used the result is nill, my question is how to get always the one that is not nill, I was thinking about the ternary operator "?" , but don't know how to use it.
Thanks,
You want the || ("or") operator:
location || location2
It returns the left side if that is not nil or false, and otherwise it returns the right side.
CSS supports logical or operations using a comma as the delimiter, so your selector can just be:
location = result.search('span.result-hood,span.nearby').text[2..-2]
XPath also supports logical or operator itself, the equivalent XPath would look like
location = result.search('//span[#class="result-hood"]|//span[#class="nearby"]').text[2..-2]
Ternary operator in ruby:
loc = location.nil? ? location2 : location
Hope this works.
Since you're looking for one or the other you can reduce this code to:
location = result.search('span.result-hood').text[2..-2]
|| result.search('span.nearby').text[2..-2]
Where that search operation could be fairly expensive, so why run it twice when you might need to run it only once. Now that you've minimized it like this you can take it a step further:
location = %w[ span.result-hood span.nearby ].map do |selector|
result.search(selector).text[2..-2]
end.compact.first
This looks a little complicated but what it does is convert each selector into the text extracted from result.search(...).text[2..-2] and then take the first non-nil value.
That technically computes all possible bits of text before extracting, so you can make it "lazy" and evaluate each one in sequence instead, stopping at the first match:
location = %w[ span.result-hood span.nearby ].lazy.map do |selector|
result.search(selector).text[2..-2]
end.select(&:itself).first
The nice thing about this approach is you can clean it up a little by declaring a constant in advance:
LOCATIONS = %w[ span.result-hood span.nearby ]
Then later you have more minimal code like this that will automatically accommodate any changes made to that array both in terms of precedence and addition of others:
location = LOCATIONS.lazy.map do |selector|
result.search(selector).text[2..-2]
end.select(&:itself).first
Related
I have to be honest that I don't quite understand Lua that well yet. I am trying to overwrite a local numeric value assigned to a set table address (is this the right term?).
The addresses are of the type:
project.models.stor1.inputs.T_in.default, project.models.stor2.inputs.T_in.default and so on with the stor number increasing.
I would like to do this in a for loop but cannot find the right expression to make the entire string be accepted by Lua as a table address (again, I hope this is the right term).
So far, I tried the following to concatenate the strings but without success in calling and then overwriting the value:
for k = 1,10,1 do
project.models.["stor"..k].inputs.T_in.default = 25
end
for k = 1,10,1 do
"project.models.stor"..j..".T_in.default" = 25
end
EDIT:
I think I found the solution as per https://www.lua.org/pil/2.5.html:
A common mistake for beginners is to confuse a.x with a[x]. The first form represents a["x"], that is, a table indexed by the string "x". The second form is a table indexed by the value of the variable x. See the difference:
for k = 1,10,1 do
project["models"]["stor"..k]["inputs"]["T_in"]["default"] = 25
end
You were almost close.
Lua supports this representation by providing a.name as syntactic sugar for a["name"].
Read more: https://www.lua.org/pil/2.5.html
You can use only one syntax in time.
Either tbl.key or tbl["key"].
The limitation of . is that you can only use constant strings in it (which are also valid variable names).
In square brackets [] you can evaluate runtime expressions.
Correct way to do it:
project.models["stor"..k].inputs.T_in.default = 25
The . in models.["stor"..k] is unnecessary and causes an error. The correct syntax is just models["stor"..k].
I'm trying to create a random number generator in Lua. I found out that I can just use math.random(1,100) to randomize a number between 1 and 100 and that should be sufficient.
But I don't really understand how to use the randomize number as variables in the script.
Tried this but of course it didn't work.
$randomCorr = math.random(1,100);
http.request_batch({
{"POST", "https://store.thestore.com/priceAndOrder/selectProduct", headers={["Content-Type"]="application/json;charset=UTF-8"}, data="{\"ChoosenPhoneModelId\":4,\"PricePlanId\":\"phone\",\"CorrelationId\":\"$randomCorr\",\"DeliveryTime\":\"1 vecka\",\"$$hashKey\":\"006\"},\"ChoosenAmortization\":{\"AmortizationLength\":0,\"ChoosenDataPackage\":{\"Description\":\"6 GB\",\"PricePerMountInKr\":245,\"DataAmountInGb\":6,\"$$hashKey\":\"00W\"},\"ChoosenPriceplan\":{\"IsPostpaid\":true,\"Title\":\"Fastpris\",\"Description\":\"Fasta kostnader till fast pris\",\"MonthlyAmount\":0,\"AvailiableDataPackages\":null,\"SubscriptionBinding\":0,\"$$hashKey\":\"00K\"}}", auto_decompress=true},
{"GET", "https://store.thestore.com/api/checkout/getproduct?correlationId=$randomCorr", auto_decompress=true},
})
In Lua, you can not start a variable name with $. This is where your main issue is at. Once the $ is removed from your code, we can easily see how to refer to variables in Lua.
randomCorr = math.random(100)
print("The random number:", randomCorr)
randomCorr = math.random(100)
print("New Random Number:", randomCorr)
Also, concatenation does not work the way you are implying it into your Http array. You have to concatenate the value in using .. in Lua
Take a look at the following example:
ran = math.random(100)
data = "{\""..ran.."\"}"
print(data)
--{"14"}
The same logic can be implied into your code:
data="{\"ChoosenPhoneModelId\":4,\"PricePlanId\":\"phone\",\"CorrelationId\":\""..randomCorr.."\",\"DeliveryTime\":\"1 vecka\",\"$$hashKey\":\"006\"},\"ChoosenAmortization\":{\"AmortizationLength\":0,\"ChoosenDataPackage\":{\"Description\":\"6 GB\",\"PricePerMountInKr\":245,\"DataAmountInGb\":6,\"$$hashKey\":\"00W\"},\"ChoosenPriceplan\":{\"IsPostpaid\":true,\"Title\":\"Fastpris\",\"Description\":\"Fasta kostnader till fast pris\",\"MonthlyAmount\":0,\"AvailiableDataPackages\":null,\"SubscriptionBinding\":0,\"$$hashKey\":\"00K\"}}"
Or you can format the value in using one of the methods provided by the string library
Take a look at the following example:
ran = math.random(100)
data = "{%q}"
print(string.format(data,ran))
--{"59"}
The %q specifier will take whatever you put as input, and safely surround it with quotations
The same logic can be applied to your Http Data.
Here is a corrected version of the code snippet:
local randomCorr = math.random(1,100)
http.request_batch({
{"POST", "https://store.thestore.com/priceAndOrder/selectProduct", headers={["Content-Type"]="application/json;charset=UTF-8"}, data="{\"ChoosenPhoneModelId\":4,\"PricePlanId\":\"phone\",\"CorrelationId\":\"" .. randomCorr .. "\",\"DeliveryTime\":\"1 vecka\",\"$$hashKey\":\"006\"},\"ChoosenAmortization\":{\"AmortizationLength\":0,\"ChoosenDataPackage\":{\"Description\":\"6 GB\",\"PricePerMountInKr\":245,\"DataAmountInGb\":6,\"$$hashKey\":\"00W\"},\"ChoosenPriceplan\":{\"IsPostpaid\":true,\"Title\":\"Fastpris\",\"Description\":\"Fasta kostnader till fast pris\",\"MonthlyAmount\":0,\"AvailiableDataPackages\":null,\"SubscriptionBinding\":0,\"$$hashKey\":\"00K\"}}", auto_decompress=true},
{"GET", "https://store.thestore.com/api/checkout/getproduct?correlationId=" .. randomCorr, auto_decompress=true},
})
There is something called $$hashKey also, in the quoted string. Not sure if that is supposed to be referencing a variable or not. If it is, it also needs to be concatenated into the resulting string, using the .. operator (just like with the randomCorr variable).
I know this code is not optimal, any ideas on how to improve it?
job_and_cost_code_found = false
timberline_db['SELECT Job, Cost_Code FROM [JCM_MASTER__COST_CODE] WHERE [Job] = ? AND [Cost_Code] = ?', job, clean_cost_code].each do |row|
job_and_cost_code_found = true
end
if job_and_cost_code_found == false then
info = linenum + "," + id + ",,Employees default job and cost code do not exist in timberline. job:#{job} cost code:#{clean_cost_code}"
add_to_exception_output_file(info)
end
You're breaking a lot of simple rules here.
Don't select what you don't use.
You select a number of columns, then completely ignore the result data. What you probably want is a count:
SELECT COUNT(*) AS cost_code_count FROM [JCM_MASTER__COST_CODE] WHERE [Job] = ? AND [Cost_Code] = ?'
Then you'll get one row that will have either a zero or non-zero value in it. Save this into a variable like:
job_and_cost_codes_found = timberline_db[...][0]['cost_code_count']
Don't compare against false unless you need to differentiate between that and nil
In Ruby only two things evaluate as false, nil and false. Most of the time you will not be concerned about the difference. On rare occasions you might want to have different logic for set true, set false or not set (nil), and only then would you test so specifically.
However, keep in mind that 0 is not a false value, so you will need to compare against that.
Taking into account the previous optimization, your if could be:
if job_and_cost_codes_found == 0
# ...
end
Don't use then or other bits of redundant syntax
Most Ruby style-guides spurn useless syntax like then, just as they recommend avoiding for and instead use the Enumerable class which is far more flexible.
Manipulate data, not strings
You're assembling some kind of CSV-like line in the end there. Ideally you'd be using the built-in CSV library to do the correct encoding, and libraries like that want data, not a string they'd have to parse.
One step closer to that is this:
line = [
linenum,
id,
nil,
"Employees default job and cost code do not exist in timberline. job:#{job} cost code:#{clean_cost_code}"
].join(',')
add_to_exception_output_file(line)
You'd presumably replace join(',') with the proper CSV encoding method that applies here. The library is more efficient when you can compile all of the data ahead of time into an array-of-arrays, so I'd recommend doing that if this is the end goal.
For example:
lines = [ ]
# ...
if (...)
# Append an array to the lines to write to the CSV file.
lines << [ ... ]
end
Keep your data in a standard structure like an Array, a Hash, or a custom object, until you're prepared to commit it to its final formatted or encoded form. That way you can perform additional operations on it if you need to do things like filtering.
It's hard to refactor this when I'm not exactly sure what it's supposed to be doing, but assuming that you want to log an error when there's no entry matching a job & code pair, here's what I've come up with:
def fetch_by_job_and_cost_code(job, cost_code)
timberline_db['SELECT Job, Cost_Code FROM [JCM_MASTER__COST_CODE] WHERE [Job] = ? AND [Cost_Code] = ?', job, cost_code]
end
if fetch_by_job_and_cost_code(job, clean_cost_code).none?
add_to_exception_output_file "#{linenum},#{id},,Employees default job and cost code do not exist in timberline. job:#{job} cost code:#{clean_cost_code}"
end
I have to search an item in an array and return the value of the next item. Example:
a = ['abc.df','-f','test.h']
i = a.find_index{|x| x=~/-f/}
puts a[i+1]
Is there any better way other than working with index?
A classical functional approach uses no indexes (xs.each_cons(2) -> pairwise combinations of xs):
xs = ['abc.df', '-f', 'test.h']
(xs.each_cons(2).detect { |x, y| x =~ /-f/ } || []).last
#=> "test.h"
Using Enumerable#map_detect simplifies it a litte bit more:
xs.each_cons(2).map_detect { |x, y| y if x =~ /-f/ }
#=> "test.h"
The reason something like array.find{something}.next doesn't exist is that it's an array rather than a linked list. Each item is just it's own value; it doesn't have a concept of "the item after me".
#tokland gives a good solution by iterating over the array with each pair of consecutive items, so that when the first item matches, you have your second item handy. There are strong arguments to be made for the functional style, to be sure. Your version is shorter, though, and I'd argue that yours is also more quickly and easily understood at a glance.
If the issue is that you're using it a lot and want something cleaner and more to the point, then of course you could just add it as a singleton method to a:
def a.find_after(&test)
self[find_index(&test).next]
end
Then
a.find_after{|x| x=~/-f/}
is a clear way to find the next item after the first match.
All of that said, I think #BenjaminCox makes the best point about what appears to be your actual goal. If you're parsing command line options, there are libraries that do that well.
I don't know of a cleaner way to do that specific operation. However, it sure looks like you're trying to parse command-line arguments. If so, I'd recommend using the built-in OptionParser module - it'll save a ton of time and hair-pulling trying to parse them yourself.
This article explains how it works.
Your solution working with indexes is fine, as others have commented. You could use Enumerable#drop_while to get an array from your match on and take the second element of that:
a = ['abc.df','-f','test.h']
f_arg = a.drop_while { |e| e !~ /-f/ }[1]
I am writing a program to better learn to program and I wish to use RSpec so that I can learn that as well. However, as is, the code isn't particularly RSpec friendly, so I need to break it up into methods so that I can test it.
I don't need anyone to write the code for me, but perhaps explain how I can break it up. I am new to programming and this kind of thing (breaking things up into methods) is a really difficult concept for me.
Here's what I have:
if params[:url] != ''
url = params[:url] #line created so I can return url more easily (or, in general)
words = params[:word].gsub("\n", ",").delete("\r").split(",") #.delete redundant?
words.reject!(&:empty?)
words.each(&:lstrip!)
return "#{words}", "#{url}" #so that I can return url, not sure how to do that yet
end
The code is a SERP checker, it takes a url and keywords and checks their location in the search engines.
For url, it'll just be the url of the website the user wishes to check... for word, it would be the keywords they wish to check their site against in Google.. a user may fill out the input form like so:
Corn on the cob,
Fibonacci,
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Your code takes a sloppy string and turns it into a clean array. You first clean up the string, then you polish the array. You could define methods for these actions.
def clean_up_words(str)
#code to clean str
str
end
def clean_up_list(arr)
#code to clean arr
arr
end
dirty_list = clean_up_words( params[:word]).split(',')
clean_list = clean_up_list( dirty_list )
def foo params
url = params[:url]
url.empty? ? nil : [params[:word].scan(/[^\s\r,]+/), url]
end
You are assigning url = params[:url]. If you are going to do that, you should do it before other places where you refer to the same thing to reduce the amount of calling [] on param.
You have several conditions on the words to be extracted. (a) Either split by "\n", ",", "\r", (b) the word should not be of 0 length, (c) white characters should be stripped off. All of this can be put together as scan(/[^\s\r,]+/).
You want to return two variables when url is not empty. Use an array in that case.