I need to be able add days or hours to a previously created Item.
The system can add or subtract a set number of hours or days based on attributes stored in the db, :operator (add/subtract), :unit_of_time(hours/days), and :number.
I'd like to be able to do something like:
Date.today+2.days
where "+" is the :operator, "2" is the :number, and "days" is the :unit_of_time but I'm unsure of how to get the interpolated string of attributes to become the actual operator "+2.days". Any ideas?
(I've poured through the ruby documentation, but to no avail. Currently, I'm just manually creating of the possible options (4) in nested if/else blocks... yeah it's gross.)
You could use eval, e.g.:
eval("Date.today+2.days")
...and then simply use string interpolation to put in the variables. Note, however, that you should only do this if you can be very certain that the values in your database are always what you want them to be; under no circumstances should users be able to change them, otherwise you'll have a major security issue which compromises your entire system.
Using more lengthy methods like the if statement you suggested (or a case statement) require you to write more code, but they are much more secure.
All ruby objects have a send method which can be used to run a method by name with parameters. Using send as well as converting strings to ints (.to_i) should suffice.
Date.today.send '+', '1'.to_i.send('months') # This works
Date.today.send operator, number.to_i.send(unit) # Generalized form
Ruby is beautiful!
Related
I should check existence of values based on some conditions.
i.e. i have 3 variables, varA, varB and varC. varC should not be empty only if varA>varB (condition).
i normally use some syntax to check any of the variables and run a frequency of any of them to see if there are errors:
if missing(varC) and (varA>varB) ck_varC=1.
if not(missing(varC)) and not(varA>varB) ck_varC=2.
exe.
fre ck_varC.
exe.
I had some errors when the condition became complex and when in the condition there are missing() or other functions but i could have made a mistake.
do you think there is an easier way of doing this checks?
thanks in advance
EDIT: here an example of what i mean, think at a questionnaire with some routing, you ask age to anyone, if they are between 17 and 44 ask them if they work, if they work ask them how many hours.
i have an excel tool where i put down all variables with all conditions, then it will generate the syntax in the example, all with the same structure for all variables, considering both situations, we have a value that shouldn't be there or we don't have a value that should be there.
is there an easier way of doing that? is this structure always valid no matter what is the condition?
In SPSS, missing values are not numbers. You need to explicitly program those scenarios as well. you got varC covered (partially), but no scenario where varA or varB have missing data is covered.
(As good practice, maybe you should initialize your check variable as sysmis or 0, using syntax):
numeric ck_varC (f1.0).
compute ck_varC=0.
if missing(varC) and (varA>varB) ck_varC=1.
if not(missing(varC)) and not(varA>varB) ck_varC=2.
***additional conditional scenarios go here:.
if missing(varA) or missing(varB) ck_varC=3.
...
fre ck_varC.
By the way - you do not need any of the exe. commands if you are going to run your syntax as a whole.
Later Edit, after the poster updated the question:
Your syntax would be something like this. Note the use of the range function, which is not mandatory, but might be useful for you in the future.
I am also assuming that work is a string variable, so its values need to be referenced using quotation signs.
if missing(age) ck_age=1.
if missing(work) and range(age,17,44) ck_work=1.
if missing(hours) and work="yes" ck_hours=1.
if not (missing (age)) and not(1>0) ck_age=2. /*this will never happen because of the not(1>0).
if not(missing(work)) and (not range(age,17,44)) ck_work=2. /*note that if age is missing, this ck_work won't be set here.
if not(missing(hours)) and (not(work="yes")) ck_hours=2.
EXECUTE.
String variables are case sensitive
There is no missing equivalent in strings; an empty blank string ("") is still a string. not(work="yes") is True when work is blank ("").
I am using Ruby on Rails 4 and, given a number, I would like to display the internationalization "second"/"seconds" string for that number. That is, I have a number (for example, 1 or 20) and I would like to display 1 second or 20 seconds (in english).
I know the date helpers but no method seems to fit for my case. How can I make that?
The usual t function eventually ends up inside the i18n gem's translate method. translate, like any sensible i18n/l10n tool, already knows about the current locale's pluralization rules. That means that you should just tell the translation system which message/string you want to how many of them you have, something like:
t('message-identifier', :count => n)
Then t will use the appropriate pluralization rules for n things in the current locale.
I use gettext for all my translation needs and it behaves this way. But there's no possible way that t wouldn't work this way too; it must work this way or it is utterly useless.
I have a field -
:Revenue
and it should accept values like 10,000.00, but if I input such value it stores 10 into database instead of 10000.00
What should I do to strip of commas before I save?
I've tried to find a few solutions online but wasn't able to implement them as I found them incomplete. If someone could help me I would really appreciate it.
**The problem now I am facing is that as soon as I enter the value rails converts string in to float value before it can run the gsub function, like if I enter 50,000.00 its converting into float 50.0 before calling the gsub, is there any way to over the to_f method which rails is calling on the string.
Removing commas is pretty simple:
value.gsub(/,/, '').to_f
Keep in mind that European formatting often uses comma as the decimal value separator so your results would be off by a factor of 100 if processing those sorts of numbers.
You can take a String#delete.
"10,000,000.00".delete(',').to_f
# => 10000000.0
I found the solution after looking at few places and combining few solutions, since I had to use gsub before the linking to model has to be done. so I created the method in my controller and called it before create and update action. and wrote the following code in the method
params[:record][:Revenue] = params[:record][:Revenue].gsub(/,/,"")
I'm working in a ruby app in which symbols are used in various places where one would usually use strings or enums in other languages (to specify configurations mostly).
So my question is, why should I not add a to_str method to symbol?
It seems seems sensible, as it allows implicit conversion between symbol and string. So I can do stuff like this without having to worry about calling :symbol.to_s:
File.join(:something, "something_else") # => "something/something_else"
The negative is the same as the positive, it implicitly converts symbols to strings, which can be REALLY confusing if it causes an obscure bug, but given how symbols are generally used, I'm not sure if this is a valid concern.
Any thoughts?
when an object does respond_to? :to_str, you expect him to really act like a String. This means it should implement all of String's methods, so you could potentially break some code relying on this.
to_s means that you get a string representation of your object, that's why so many objects implement it - but the string you get is far from being 'semantically' equivalent to your object ( an_hash.to_s is far from being a Hash ). :symbol.to_str's absence reflects this : a symbol is NOT and MUST NOT be confused with a string in Ruby, because they serve totally different purposes.
You wouldn't think about adding to_str to an Int, right ? Yet an Int has a lot of common with a symbol : each one of them is unique. When you have a symbol, you expect it to be unique and immutable as well.
You don't have to implicitly convert it right? Because doing something like this will automatically coerce it to a string.
"#{:something}/something_else" # "something/something_else"
The negative is what you say--at one point, anyway, some core Ruby had different behavior based on symbol/string. I don't know if that's still the case. The threat alone makes me a little twitchy, but I don't have a solid technical reason at this point. I guess the thought of making a symbol more string-like just makes me nervous.
I'm making a web app where the point is to change a given word by one letter. For example, if I make a post by selecting the word: "best," then the first reply could be "rest," while the one after that should be "rent," "sent", etc. So, the word a user enters must have changed by one letter from the last submitted word. It would be constantly evolving.
Right now you can make a game and respond just by typing a word. I coded up a custom validation using functionality from the Amatch gem:
http://flori.github.com/amatch/doc/index.html
Posts have many responses, and responses belong to a post.
here's the code:
def must_have_changed_by_one_letter
m = Amatch::Sellers.new(title.strip)
errors.add_to_base("Sorry, you must change the last submitted word by one letter")
if m.match(post.responses.last.to_s.strip) != 1.0
end
When I try entering a new response for a test post I made (original word "best", first response is "rest") I get this:
ActiveRecord::RecordInvalid in ResponsesController#create
Validation failed: Sorry, you must change the last submitted word by one letter
Any thoughts on what might be wrong?
Thanks!
Looks like there are a couple of potential issues here.
For one, is your if statement actually on a separate line than your errors.add_to_base... statement? If so, your syntax is wrong; the if statement needs to be in the same line as the statement it's modifying. Even if it is actually on the correct line, I would recommend against using a trailing if statement on such a long line; it will make it hard to find the conditional.
if m.match(post.responses.last.to_s.strip) != 1.0
errors.add_to_base("Sorry, you must change the last submitted word by one letter")
end
Second, doing exact equality comparison on floating point numbers is almost never a good idea. Because floating point numbers involve approximations, you will sometimes get results that are very close, but not quite exactly equal, to a given number that you are comparing against. It looks like the Amatch library has several different classes for comparing strings; the Sellers class allows you to set different weights for different kinds of edits, but given your problem description, I don't think you need that. I would try using the Levenshtein or Hamming distance instead, depending on your exact needs.
Finally, if neither of those suggestions work, try writing out to a log or in the response the exact values of title.strip and post.responses.last.to_s.strip, to make sure you are actually comparing the values that you think you're comparing. I don't know the rest of your code, so I can't tell you whether those are correct or not, but if you print them out somewhere, you should be easily able to check them yourself.