I have a non-Rails project in which I am loading some settings from a YAML file:
config = YAML::load File.open("#{LOG_ROOT}/config/database.yml")
I can only access this hash like config["host"], config["username"] etc.
I want indifferent access so I can use both :host and "host".
The reason is, that one of the gems in the project to which I am passing this hash seems to be accessing it using symbols and it fails currently.
What is the best way to create a hash with indifferent access in this scenario?
You lose nothing except a few kB of disk space by installing the Active Support gem. In your code, you require only the function you want:
require 'active_support/core_ext/hash/indifferent_access'
That way, you can be sure you are not getting anything else to mess up your namespace.
Let the config hash return the value for the stringified version of the key:
config = {"host"=>"value1", "Username"=>"Tom"}
config.default_proc = proc{|h, k| h.key?(k.to_s) ? h[k.to_s] : nil}
p config[:host] #=> "value1"
The default_proc runs everytime when a key is not found in the hash. Note this is only half of indifferent access: config["host"] will result in nil if the key :host is present. If that has to work too:
config.default_proc = proc do |h, k|
case k
when String then sym = k.to_sym; h[sym] if h.key?(sym)
when Symbol then str = k.to_s; h[str] if h.key?(str)
end
end
See the comments about limitations of this approach (tltr: separate values for :a and 'a' are possible, does not take into account Hash.delete and others).
Related
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)
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 want to break down a JSON string into smaller objects. I have two servers, one acting as the web-app interface to the whole application and the other is a repository/database.
I'm able to retrieve information from the repository to the web-app as JSON, but after that I don't know how to return it.
Here's a sample of the JSON being returned:
{"respPages":[{"page":{"page_url":"http://www.google.com/","created_at":"2011-08-10T11:00:19Z","website_id":1,"updated_at":"2011-08-10T11:00:19Z","id":1}},{"page":{"page_url":"http://www.blank.com/services/content_services/","created_at":"2011-08-10T11:02:46Z","website_id":1,"updated_at":"2011-08-10T11:02:46Z","id":2}}],"respSite":{"website":{"created_at":"2011-08-10T11:00:19Z","website_id":null,"updated_at":"2011-08-10T11:00:19Z","website_url":null,"id":1}},"respElementTypes":[{"element_type":{"created_at":"2011-08-10T11:00:19Z","updated_at":"2011-08-10T11:00:19Z","id":1,"tag_name":"head"}},
There are four tags in the JSON:
page
website
elementType
elementData
I would like to create four arrays and populate them with the object that matches these tags.
I would image the code is something like this:
#Get the json from repo using net/http
uri = URI.parse("http://127.0.0.1:3007/repository/infoid/1.json")
http = Net::HTTP.new(uri.host, uri.port)
response = http.request(Net::HTTP::Get.new(uri.request_uri))
#x = response.to_hash
#pages = Array.new
#websites= Array.new
#elementDatas = Array.new
#elementTypes = Array.new
#enter code here`#For every bit of the hash, find out what it is and allocate it accordingly
#x.each_with_index do |e,index|
if e.tagName == pages #Getting real javascripty here. There must be someway to check the tag or title of the element
#pages[index]=e
end
My goal for the returned value is to have four arrays, each containing different types of objects:
#pagesArray[1]
should contain the first occurrence of a page object in the JSON string. Then do the same for the other ones.
Of course I'd need to break down the object further but once I can break down the top level and categorize them, then I can go deeper.
In the JSON there are already tag titles respPages and respWebsites which group all the objects.
How do I turn JSON back into objects in Ruby and reference them using something like the tag name?
You should be able to decode anything in JSON format using the standard JSON library:
JSON.load(...)
It will throw exceptions on malformed JSON data, so be sure to test it thoroughly and make sure it can handle all the important cases.
If you're trying to navigate the structure of the JSON itself, you probably need to write a series of recursive methods that handle each case along the way. A good pattern to start with is this:
#data.each do |key, value|
case (key)
when 'someKey'
handle_some_key(value)
when 'otherKey'
handle_other_key(value)
end
end
You can either break out the behavior into methods as in this example, or inline it if the logic is fairly straightforward.
As a note, an alternative to Array.new is simply [ ] as it is in JavaScript. For example:
#pages = [ ]
You'll see this used frequently in most Ruby examples. The alternative to Hash.new is { }.
The following works:
json = {"respPages"=>[{"page"=>{"page_url"=>"http://www.google.com", "created_at"=>"2011-08-10T11:00:19Z", "website_id"=>1, "updated_at"=>"2011-08-10T11:00:19Z", "id"=>1}}, {"page"=>{"page_url"=>"http://www.blank.com/services/content_services/", "created_at"=>"2011-08-10T11:02:46Z", "website_id"=>1, "updated_at"=>"2011-08-10T11:02:46Z", "id"=>2}}],
"respSite"=>{"website"=>{"created_at"=>"2011-08-10T11:00:19Z", "website_id"=>nil, "updated_at"=>"2011-08-10T11:00:19Z", "website_url"=>nil, "id"=>1}},
"respElementTypes"=>[{"element_type"=>{"created_at"=>"2011-08-10T11:00:19Z", "updated_at"=>"2011-08-10T11:00:19Z", "id"=>1, "tag_name"=>"head"}}]}
#respPages, #respSite, #respElementTypes = [], [], []
json.each do |key_category, group_category|
group_category.each do |hash|
if group_category.is_a? Array
eval("##{key_category}") << hash.values.first
elsif group_category.is_a? Hash
eval("##{key_category}") << hash[1]
end
end
end
there weren't any respData in your sample but you've got the idea.
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.
I have a rails application that is using attachment_fu. Currently, it is using :file_system for storage, but I want to change it to :s3, to allow for better scaling as more files get uploaded.
What is involved with this? I imagine that if I just switch the code to use :s3, all the old links will be broken. Do I need to just copy the existing files from the file system to S3? A google search hasn't turned up much on the topic.
I would prefer to move the existing files over to S3, so everything is in the same place, but if necessary, the old files can stay where they are, as long as new ones go to S3.
EDIT: So, it is not as simple as copying over the files to S3; the URLs are created using a different scheme. When they are stored in :file_system, the files end up in places like /public/photos/0000/0001/file.name, but the same file in :s3 might end up in 0/1/file.name. I think it is using the id something, and just padding it (or not) with zeros, but I'm not sure of that.
That's correct. The ids are padded using :file_system storage.
Instead of renaming all your files, you can alter the s3 backend module to use padded numbers as well.
Copy the partitioned_path method from file_system_backend.rb and put it in s3_backend.rb.
def partitioned_path(*args)
if respond_to?(:attachment_options) && attachment_options[:partition] == false
args
elsif attachment_options[:uuid_primary_key]
# Primary key is a 128-bit UUID in hex format. Split it into 2 components.
path_id = attachment_path_id.to_s
component1 = path_id[0..15] || "-"
component2 = path_id[16..-1] || "-"
[component1, component2] + args
else
path_id = attachment_path_id
if path_id.is_a?(Integer)
# Primary key is an integer. Split it after padding it with 0.
("%08d" % path_id).scan(/..../) + args
else
# Primary key is a String. Hash it, then split it into 4 components.
hash = Digest::SHA512.hexdigest(path_id.to_s)
[hash[0..31], hash[32..63], hash[64..95], hash[96..127]] + args
end
end
end
Modify s3_backend.rb's full_filename method to use the partitioned_path.
def full_filename(thumbnail = nil)
File.join(base_path, *partitioned_path(thumbnail_name_for(thumbnail)))
end
attachment_fu will now create paths with the same names as it did with the file_system backend, so you can just copy your files over to s3 without renaming everything.
In addition to nilbus' answer, I had to modify s3_backend.rb's base_path method to return an empty string, otherwise it would insert the attachment_path_id twice:
def base_path
return ''
end
What worked for me, in addition to nilbus's answer, was to modify s3_backend.rb's base_path method to still use the path_prefix (which is by default the table name):
def base_path
attachment_options[:path_prefix]
end
And also, I had to take the attachment_path_id from file_system_backend.rb and replace the one in s3_backend.rb, since otherwise partitioned_path always thought my Primary Key was a String:
def attachment_path_id
((respond_to?(:parent_id) && parent_id) || id) || 0
end
Thanks for all those responses which helped a lot. It worked for me too but I had to do this in order to have the :thumbnail_class option working :
def full_filename(thumbnail = nil)
prefix = (thumbnail ? thumbnail_class : self).attachment_options[:path_prefix].to_s
File.join(prefix, *partitioned_path(thumbnail_name_for(thumbnail)))
end