I'm using Rails.logger.debug print variables for debugging purposes. The issue is it prints hashes in an impossible to read format (can't distinguish keys from values). For example, I add the following lines to my code base
#code_base.rb
my_hash = {'a' => 'alligator', 'b'=>'baboon'}
Rails.logger.debug my_hash
Then I launch my rails app and type
tail -f log/development.log
But when my_hash gets printed, it looks like
bbaboonaalligator
The key and values are scrunched up, making it impossible to parse. Do you guys know what I should do to fix this?
Nevermind, I found the answer to my own question. I need to use
my_hash = {'a' => 'alligator', 'b'=>'baboon'}
Rails.logger.debug "#{my_hash.inspect}"
Then, it looks like
{"b"=>"baboon", "a"=>"aligator"}
It's even easier to read it when you use to_yaml eg:
logger.debug my_hash.to_yaml
Which is an easy to read format over multiple lines. The inspect method simply spews out a string.
my_hash = {'a' => 'alligator', 'b'=>'baboon'}
logger.debug "#{my_hash}"
Then, it looks like
{"b"=>"baboon", "a"=>"aligator"}
do not need inspect
There is an another way to do this. There is a ruby built in module pp.rb that is Pretty-printer for Ruby objects.
non-pretty-printed output by p is:
#<PP:0x81fedf0 #genspace=#<Proc:0x81feda0>, #group_queue=#<PrettyPrint::GroupQueue:0x81fed3c #queue=[[#<PrettyPrint::Group:0x81fed78 #breakables=[], #depth=0, #break=false>], []]>, #buffer=[], #newline="\n", #group_stack=[#<PrettyPrint::Group:0x81fed78 #breakables=[], #depth=0, #break=false>], #buffer_width=0, #indent=0, #maxwidth=79, #output_width=2, #output=#<IO:0x8114ee4>>
pretty-printed output by pp is:
#<PP:0x81fedf0
#buffer=[],
#buffer_width=0,
#genspace=#<Proc:0x81feda0>,
#group_queue=
#<PrettyPrint::GroupQueue:0x81fed3c
#queue=
[[#<PrettyPrint::Group:0x81fed78 #break=false, #breakables=[], #depth=0>],
[]]>,
#group_stack=
[#<PrettyPrint::Group:0x81fed78 #break=false, #breakables=[], #depth=0>],
#indent=0,
#maxwidth=79,
#newline="\n",
#output=#<IO:0x8114ee4>,
#output_width=2>
For more complex objects even with ActiveRecord, this could be achieved with a JSON.pretty_generate
Rails.logger.debug JSON.pretty_generate(my_hash.as_json)
Related
I need to output some JSON for a customer in a somewhat unusual format. My app is written with Rails 5.
Desired JSON:
{
"key": "\/Date(0000000000000)\/"
}
The timestamp value needs to have a \/ at both the start and end of the string. As far as I can tell, this seems to be a format commonly used in .NET services. I'm stuck trying to get the slashes to output correctly.
I reduced the problem to a vanilla Rails 5 application with a single controller action. All the permutations of escapes I can think of have failed so far.
def index
render json: {
a: '\/Date(0000000000000)\/',
b: "\/Date(0000000000000)\/",
c: '\\/Date(0000000000000)\\/',
d: "\\/Date(0000000000000)\\/"
}
end
Which outputs the following:
{
"a": "\\/Date(0000000000000)\\/",
"b": "/Date(0000000000000)/",
"c": "\\/Date(0000000000000)\\/",
"d": "\\/Date(0000000000000)\\/"
}
For the sake of discussion, assume that the format cannot be changed since it is controlled by a third party.
I have uploaded a test app to Github to demonstrate the problem. https://github.com/gregawoods/test_app_ignore_me
After some brainstorming with coworkers (thanks #TheZanke), we came upon a solution that works with the native Rails JSON output.
WARNING: This code overrides some core behavior in ActiveSupport. Use at your own risk, and apply judicious unit testing!
We tracked this down to the JSON encoding in ActiveSupport. All strings eventually are encoded via the ActiveSupport::JSON.encode. We needed to find a way to short circuit that logic and simply return the unencoded string.
First we extended the EscapedString#to_json method found here.
module EscapedStringExtension
def to_json(*)
if starts_with?('noencode:')
"\"#{self}\"".gsub('noencode:', '')
else
super
end
end
end
module ActiveSupport::JSON::Encoding
class JSONGemEncoder
class EscapedString
prepend EscapedStringExtension
end
end
end
Then in the controller we add a noencode: flag to the json hash. This tells our version of to_json not to do any additional encoding.
def index
render json: {
a: '\/Date(0000000000000)\/',
b: 'noencode:\/Date(0000000000000)\/',
}
end
The rendered output shows that b gives us what we want, while a preserves the standard behavior.
$ curl http://localhost:3000/sales/index.json
{"a":"\\/Date(0000000000000)\\/","b":"\/Date(0000000000000)\/"}
Meditate on this:
Ruby treats forward-slashes the same in double-quoted and single-quoted strings.
"/" # => "/"
'/' # => "/"
In a double-quoted string "\/" means \ is escaping the following character. Because / doesn't have an escaped equivalent it results in a single forward-slash:
"\/" # => "/"
In a single-quoted string in all cases but one it means there's a back-slash followed by the literal value of the character. That single case is when you want to represent a backslash itself:
'\/' # => "\\/"
"\\/" # => "\\/"
'\\/' # => "\\/"
Learning this is one of the most confusing parts about dealing with strings in languages, and this isn't restricted to Ruby, it's something from the early days of programming.
Knowing the above:
require 'json'
puts JSON[{ "key": "\/value\/" }]
puts JSON[{ "key": '/value/' }]
puts JSON[{ "key": '\/value\/' }]
# >> {"key":"/value/"}
# >> {"key":"/value/"}
# >> {"key":"\\/value\\/"}
you should be able to make more sense of what you're seeing in your results and in the JSON output above.
I think the rules for this were originally created for C, so "Escape sequences in C" might help.
Hi I think this is the simplest way
.gsub("/",'//').gsub('\/','')
for input {:key=>"\\/Date(0000000000000)\\/"} (printed)
first gsub will do{"key":"\\//Date(0000000000000)\\//"}
second will get you
{"key":"\/Date(0000000000000)\/"}
as you needed
When a user uses my application, at one point they will get an array of arrays, that looks like this:
results = [["value",25], ["value2",30]...]
The sub arrays could be larger, and will be in a similar format. I want to allow my users to write their own custom transform function that will take an array of arrays, and return either an array of arrays, a string, or a number. A function should look like this:
def user_transform_function(array_of_arrays)
# eval users code, only let them touch the array of arrays
end
Is there a safe way to sandbox this function and eval so a user could not try and execute malicious code? For example, no web callouts, not database callouts, and so on.
First, if you will use eval, it will never be safe. You can at least have a look in the direction of taint method.
What I would recommend is creating your own DSL for that. There is a great framework in Ruby: http://treetop.rubyforge.org/index.html. Of course, it will require some effort from your side, but from the user prospective I think it could be even better.
WARNING: I can not guarantee that this is truly safe!
You might be able to run it as a separate process and use ruby $SAFE, however this does not guarantee that what you get is safe, but it makes it harder to mess things up.
What you then would do is something like this:
script = "arr.map{|e| e+2}" #from the user.
require "json"
array = [1, 2, 3, 4]
begin
results = IO.popen("ruby -e 'require \"json\"; $SAFE=3; arr = JSON.parse(ARGV[0]); puts (#{script}).to_json' #{array.to_json}") do |io|
io.read
end
rescue Exception => e
puts "Ohh, good Sir/Mam, your script caused an error."
end
if results.include?("Insecure operation")
puts "Ohh, good Sir/Mam, you cannot do such a thing"
else
begin
a = JSON.parse(results)
results = a
rescue Exception => e
puts "Ohh, good Sir/Mam, something is wrong with the results."
puts results
end
end
conquer_the_world(results) if results.is_a?(Array)
do_not_conquer_the_world(results) unless results.is_a?(Array)
OR
You could do this, it appears:
def evaluate_user_script(script)
Thread.start {
$SAFE = 4
eval(script)
}
end
But again: I do not know how to get the data out of there.
I'm having trouble with a regex in Ruby (on Rails). I'm relatively new to this.
The test string is:
http://www.xyz.com/017010830343?$ProdLarge$
I am trying to remove "$ProdLarge$". In other words, the $ signs and anything between.
My regular expression is:
\$\w+\$
Rubular says my expression is ok. http://rubular.com/r/NDDQxKVraK
But when I run my code, the app says it isn't finding a match. Code below:
some_array.each do |x|
logger.debug "scan #{x.scan('\$\w+\$')}"
logger.debug "String? #{x.instance_of?(String)}"
x.gsub!('\$\w+\$','scl=1')
...
My logger debug line shows a result of "[]". String is confirmed as being true. And the gsub line has no effect.
What do I need to correct?
Use /regex/ instead of 'regex':
> "http://www.xyz.com/017010830343?$ProdLarge$".gsub(/\$\w+\$/, 'scl=1')
=> "http://www.xyz.com/017010830343?scl=1"
Don't use a regex for this task, use a tool designed for it, URI. To remove the query:
require 'uri'
url = URI.parse('http://www.xyz.com/017010830343?$ProdLarge$')
url.query = nil
puts url.to_s
=> http://www.xyz.com/017010830343
To change to a different query use this instead of url.query = nil:
url.query = 'scl=1'
puts url.to_s
=> http://www.xyz.com/017010830343?scl=1
URI will automatically encode values if necessary, saving you the trouble. If you need even more URL management power, look at Addressable::URI.
I am working with a hash called my_hash :
{"2011-02-01 00:00:00+00"=>816, "2011-01-01 00:00:00+00"=>58, "2011-03-01 00:00:00+00"=>241}
First, I try to parse all the keys, in my_hash (which are times).
my_hash.keys.sort.each do |key|
parsed_keys << Date.parse(key).to_s
end
Which gives me this :
["2011-01-01", "2011-02-01", "2011-03-01"]
Then, I try to map parsed_keys back to the keys of my_hash :
Hash[my_hash.map {|k,v| [parsed_keys[k], v]}]
But that returns the following error :
TypeError: can't convert String into Integer
How can I map parsed_keys back to the keys of my_hash ?
My aim is to get rid of the "00:00:00+00" at end of all the keys.
Why don't you just do this?
my_hash.map{|k,v| {k.gsub(" 00:00:00+00","") => v}}.reduce(:merge)
This gives you
{"2011-02-01"=>816, "2011-01-01"=>58, "2011-03-01"=>241}
There is a new "Rails way" methods for this task :)
http://api.rubyonrails.org/classes/Hash.html#method-i-transform_keys
Using iblue answer, you could use a regexp to handle this situation, for example:
pattern = /00:00:00(\+00)+/
my_hash.map{|k,v| {k.gsub(pattern,"") => v}}.reduce(:merge)
You could improve the pattern to handle different situations.
Hope it helps.
Edit:
Sorry, iblue have already posted the answer
Another alternative could be:
map
return converted two elements array [converted_key, converted_value]
convert back to a hash
irb(main):001:0> {a: 1, b: 2}.map{|k,v| [k.to_s, v.to_s]}.to_h
=> {"a"=>"1", "b"=>"2"}
I need to load a yaml file into Hash,
What should I do?
I would use something like:
hash = YAML.load(File.read("file_path"))
A simpler version of venables' answer:
hash = YAML.load_file("file_path")
Use the YAML module:
http://ruby-doc.org/stdlib-1.9.3/libdoc/yaml/rdoc/YAML.html
node = YAML::parse( <<EOY )
one: 1
two: 2
EOY
puts node.type_id
# prints: 'map'
p node.value['one']
# prints key and value nodes:
# [ #<YAML::YamlNode:0x8220278 #type_id="str", #value="one", #kind="scalar">,
# #<YAML::YamlNode:0x821fcd8 #type_id="int", #value="1", #kind="scalar"> ]'
# Mappings can also be accessed for just the value by accessing as a Hash directly
p node['one']
# prints: #<YAML::YamlNode:0x821fcd8 #type_id="int", #value="1", #kind="scalar">
http://yaml4r.sourceforge.net/doc/page/parsing_yaml_documents.htm
You may run into a problem mentioned at this related question, namely, that the YAML file or stream specifies an object into which the YAML loader will attempt to convert the data into. The problem is that you will need a related Gem that knows about the object in question.
My solution was quite trivial and is provided as an answer to that question. Do this:
yamltext = File.read("somefile","r")
yamltext.sub!(/^--- \!.*$/,'---')
hash = YAML.load(yamltext)
In essence, you strip the object-classifier text from the yaml-text. Then you parse/load it.