I am trying to use the "food_descriptions" fixture in a "minitest" test in Rails 4 beta1:
butter:
NDB_No: "01001"
FdGrp_Cd: "0100"
Long_Desc: "Butter, salted"
The test I have is this:
it "must work" do
food_descriptions(:butter).NDB_No.must_equal "01001"
end
However, when I run the test I get this error: Expected: "01001" Actual: 1001
I don't understand why that number is not recognized as a string. I've read that yml treats values that start with 0 as octal values, so adding the quotes should be enough to treat it as a string but is not working. I have also try the pipe "|" sign but doesn't work either.
Any idea why?
Quick Answer (TL;DR)
YAML 1.2 leading zeros can be preserved by quoting a scalar value.
Context
YAML 1.2
Scalar value with leading zeros
Problem
Scenario: Developer wishes to specify a scalar value with leading zero in a YAML 1.2 file.
When parsed, the leading zero gets omitted or truncated
Solution
Quote a scalar value in YAML to have it parsed as a string.
Leading zeros are preserved for non-numeric values.
Pitfalls
Data type casting for databases or programming language context may convert string scalar to numeric scalar value.
It turns out the problem is not what I thought it was (yml). The problem was that the fixtures were being pushed to the DB and the tests were actually retrieving the entry from the database (I thought the fixture were just in memory), and the database column type for that value was integer, not string, thus the leading zeros were being removed. My real problem was that I wanted that column to be the primary key of the table of type string and I didn't realize that the migration I created didn't change the type of the column to string in the test database.
Related
I've been looking for a good way to see if a string of items are all numbers, and thought there might be a way of specifying a range from 0 to 9 and seeing if they're included in the string, but all that I've looked up online has really confused me.
def validate_pin(pin)
(pin.length == 4 || pin.length == 6) && pin.count("0-9") == pin.length
end
The code above is someone else's work and I've been trying to identify how it works. It's a pin checker - takes in a set of characters and ensures the string is either 4 or 6 digits and all numbers - but how does the range work?
When I did this problem I tried to use to_a? Integer and a bunch of other things including ranges such as (0..9) and ("0..9) and ("0".."9") to validate a character is an integer. When I saw ("0-9) it confused the heck out of me, and half an hour of googling and youtube has only left me with regex tutorials (which I'm interested in, but currently just trying to get the basics down)
So to sum this up, my goal is to understand a more semantic/concise way to identify if a character is an integer. Whatever is the simplest way. All and any feedback is welcome. I am a new rubyist and trying to get down my fundamentals. Thank You.
Regex really is the right way to do this. It's specifically for testing patterns in strings. This is how you'd test "do all characters in this string fall in the range of characters 0-9?":
pin.match(/\A[0-9]+\z/)
This regex says "Does this string start and end with at least one of the characters 0-9, with nothing else in between?" - the \A and \z are start-of-string and end-of-string matchers, and the [0-9]+ matches any one or more of any character in that range.
You could even do your entire check in one line of regex:
pin.match(/\A([0-9]{4}|[0-9]{6})\z/)
Which says "Does this string consist of the characters 0-9 repeated exactly 4 times, or the characters 0-9, repeated exactly 6 times?"
Ruby's String#count method does something similar to this, though it just counts the number of occurrences of the characters passed, and it uses something similar to regex ranges to allow you to specify character ranges.
The sequence c1-c2 means all characters between c1 and c2.
Thus, it expands the parameter "0-9" into the list of characters "0123456789", and then it tests how many of the characters in the string match that list of characters.
This will work to verify that a certain number of numbers exist in the string, and the length checks let you implicitly test that no other characters exist in the string. However, regexes let you assert that directly, by ensuring that the whole string matches a given pattern, including length constraints.
Count everything non-digit in pin and check if this count is zero:
pin.count("^0-9").zero?
Since you seem to be looking for answers outside regex and since Chris already spelled out how the count method was being implemented in the example above, I'll try to add one more idea for testing whether a string is an Integer or not:
pin.to_i.to_s == pin
What we're doing is converting the string to an integer, converting that result back to a string, and then testing to see if anything changed during the process. If the result is =>true, then you know nothing changed during the conversion to an integer and therefore the string is only an Integer.
EDIT:
The example above only works if the entire string is an Integer and won’t properly deal with leading zeros. If you want to check to make sure each and every character is an Integer then do something like this instead:
pin.prepend(“1”).to_i.to_s(1..-1) == pin
Part of the question seems to be exactly HOW the following portion of code is doing its job:
pin.count("0-9")
This piece of the code is simply returning a count of how many instances of the numbers 0 through 9 exist in the string. That's only one piece of the relevant section of code though. You need to look at the rest of the line to make sense of it:
pin.count("0-9") == pin.length
The first part counts how many instances then the second part compares that to the length of the string. If they are equal (==) then that means every character in the string is an Integer.
Sometimes negation can be used to advantage:
!pin.match?(/\D/) && [4,6].include?(pin.length)
pin.match?(/\D/) returns true if the string contains a character other than a digit (matching /\D/), in which case it it would be negated to false.
One advantage of using negation here is that if the string contains a character other than a digit pin.match?(/\D/) would return true as soon as a non-digit is found, as opposed to methods that examine all the characters in the string.
I am trying to save a numeric-with-decimal-places(f8.6) variable from an SPSS file into a fixed ASCII file. The goal is to write it into certain columns of the ASCII (21 to 30).
WRITE OUTFILE='C:\misc\ascii.dat'
ENCODING='UTF8'
TABLE /1
variable 21-30.
exe.
writes to the correct positions, but not with decimals.
variable 21-30 (f)
does the same thing.
variable (f8.6)
saves with decimals, but on positions 1 to 10.
variable 21-30 (f8.6)
results in an error, because apparently you cannot specify both columns and format.
I know two workarounds, but both involve additional data editing, which I'd rather not do:
Convert variable to string and save it as string - but I am not sure about the implications (encoding, decimal places, or whatever other thing I am not even considering)
add an empty string variable with length of 20 before my variable.
But is there a straightforward way of doing this, without workarounds ?
You can add the 20 spaces in the command itself, like this:
WRITE OUTFILE='C:\misc\ascii.dat'
ENCODING='UTF8'
TABLE / ' ' YourNumVar (f8.6) .
exe.
I use an ODBC table handler to read data from Excel and CSV files into an AMPL model. But the thing I encountered probably doesn't have much to do with the precise programs and programming language I use.
Among the data are two specific types of strings: three-digit alphabetic and six-digit alphanumeric.
When the three-digit alphabetic type includes a NAN string, AMPL throws an error. As I found out, the reason is that it understands NAN as "NaN" (not a number). It cannot use this as an index.
The six-digit alphanumeric type sometimes include strings like 3E1234. This seems to be a problem because AMPL (or the handler) understands this as a number in scientific notation. So it reads 3*10^1234, which is handled as infinity. So when there is one 3E1234 entry and one 3E1235 entry, it sees them both as infinity.
I understand these two. And although they are annoying, I can work with that. Now I encountered that a string SK1234 is parsed as the number 1234. I have learned a bit of programming in college, but I don't have any idea why this happens. Is the prefix SK anything special?
EDIT: Here is an example that reproduces the error:
The model file:
set INDEX;
param value;
The "run" file:
table Table1 IN "tableproxy" "odbc" "DSN=NDE" "Test.csv": INDEX <- [Index], value ~ Value;
read table Table1;
NDE is a user DSN that uses the Microsoft Text Driver in the appropriate folder.
And the CSV file:
Index,Value
SK1202,1
SK1445,2
SK0124,3
SK7896,4
SK1,5
AB1234,6
After running all this code, I type display INDEX and get
set INDEX := 1202 1445 124 7896 1 Missing;
So the field Index is treated as a numeric field with the first five entries converted to a number. The last entry cannot be converted so it is treated as Missing.
The DSN's setting is that it sets the type according to the first 25 lines. For some reason, it understands the SK... entries as numbers and therefore reads all as numbers.
For the Text ODBC driver to detect column type correctly, values should be quoted:
Index,Value
'SK1202',1
'SK1445',2
'SK0124',3
'SK7896',4
'SK1',5
'AB1234',6
throwing an error when trying to access hashmap with key with a numeric value or special chars
Here is the code I am trying to use:
<div th:include="${myMap[__${dept.code}__]}"/>
If code has letters , this works fine, but if it holds only a numeric value "1234" , this fails .
Appreciate any resolution on this. Thanks..
If the map is based on string keys you shpuld ensure that the precomputed expression is always a string.
A TextLiteral expression can only consist of a limited type of characters. A-z, underscores, minus and some others.
To ensure it's always a string you can wrap the precomputed expression in single quotes:
<div th:include="${myMap['__${dept.code}__']}"/>
I am doing some client side validation in ASP.NET MVC and I found myself trying to do conditional validation on a set of items (ie, if the checkbox is checked then validate and visa versa). This was problematic, to say the least.
To get around this, I figured that I could "cheat" by having a hidden element that would contain all of the information for each set, thus the idea of a CSV string containing this information.
I already use a custom [HiddenRequired] attribute to validate if the hidden input contains a value, with success, but I thought as I will need to validate each piece of data in the csv, that a regular expression would solve this.
My regular expression work is extremely weak and after a good 2 hours I've almost given up.
This is an example of the csv string:
true,3,24,over,0.5
to explain:
true denotes if I should validate the rest. I need to conditionally switch in the regex using this
3 and 24 are integers and will only ever fall in the range 0-24.
over is a string and will either be over or under
0.5 is a decimal value, of unknown precision.
In the validation, all values should be present and at least of the correct type
Is there someone who can either provide such a regex or at least provide some hints, i'm really stuck!
Try this regex:
#"^(true,([01]?\d|2[0-4]),([01]?\d|2[0-4]),(over|under),\d+\.?\d+|false.*)$"
I'll try to explain it using comments. Feel free to ask if anything is unclear. =)
#"
^ # start of line
(
true, # literal true
([01]?\d # Either 0, 1, or nothing followed by a digit
| # or
2[0-4]), # 20 - 24
([01]?\d|2[0-4]), # again
(over|under), # over or under
\d+\.?\d+ # any number of digits, optional dot, any number of digits
| #... OR ...
false.* # false followed by anything
)
$ # end of line
");
I would probably use a Split(',') and validate elements of the resulting array instead of using a regex. Also you should watch out for the \, case (the comma is part of the value).