Is there a more elegant way to write this in Ruby, maybe using a loop?
def save_related_info
update_column(:sender_company_name, user.preference.company_name)
update_column(:sender_address, user.preference.address)
update_column(:sender_telephone, user.preference.telephone)
update_column(:sender_email, user.preference.email)
update_column(:sender_url, user.preference.url)
update_column(:sender_vat_number, user.preference.vat_number)
update_column(:sender_payment_details, user.preference.payment_details)
end
Thanks for any help.
Any reason you're not using update_attributes to do them all at once?
def save_related_info
update_attributes(
:sender_company_name => user.preference.company_name,
:sender_address => user.preference.address,
:sender_telephone => user.preference.telephone,
:sender_email => user.preference.email,
:sender_url => user.preference.url,
:sender_vat_number => user.preference.vat_number,
:sender_payment_details => user.preference.payment_details
)
end
def save_related_info
%w[company_name address telephone email url vat_number payment_details]
.each{|s| update_column("sender_#{s}".to_sym, user.preference.send(s))}
end
first guess is to put keys in and values in lists and then use loop. something like this:
keys = ['key1', 'key2', 'key3', 'key4']
values = [val1, val2, val3, val4]
keys.each_index do |i|
update_column(keys[i], values[i])
end
Minus in that approach is that the order of elements in values array should fit for order of keys. You could avoid it of using hash instead of arrays. Code will looks like this:
data = { "key1" => val1, "key2" => val2, "key3" => val3 };
data.each do |key, value|
update_column(keys, values)
end
Related
I have the following snippet of code to fetch certain columns from the db:
#data = Topic.select("id,name").where("id in (?)",#question.question_topic.split(",")).map(&:attributes)
In the resulting Array of Hashes which is :
Current:
#data = [ { "id" => 2, "name" => "Sports" }]
To be changed to:
#data = [ { "id" => "2", "name" => "Sports" }]
I want to convert "id" to string from fixnum. Id is integer in the db. What is the cleanest way to do this?
Note: After using .map(&:attributes) it is not an active record relation.
You can do it with proper map usage:
topics = Topic.select("id,name").where("id in (?)",#question.question_topic.split(","))
#data = topics.map do |topic|
{
'id' => topic.id.to_s,
'name' => topic.name
}
end
What you're looking for is simply
#data.each { |obj| obj["id"] = obj["id"].to_s }
There isn't really a simpler way (I think that's straightforward enough anyway).
Going by the title which implies a different question - converting every value in the hash to a string you can do this:
#data.each do |obj|
obj.map do |k, v|
{k => v.to_s}
end
end
Just leaving that there anyway.
You can use Ruby's #inject here:
#data.map do |datum|
new_datum = datum.inject({}) do |converted_datum, (key, value)|
converted_datum[key] = value.to_s
converted_datum
end
end
This will work to convert all values to strings, regardless of the key.
If you are using Rails it can be even cleaner with Rails' #each_with_object:
#data.map do |datum|
datum.each_with_object({}) do |(key, value), converted_datum|
converted_datum[key] = value.to_s
end
end
This will iterate all the key names in the hash and replace the value with the #to_s version of the datum associated with the key. nil's converted to empty strings. Also, this assumes you don't have complex data within the hash like embedded arrays or other hashes.
def hash_values_to_string(hash)
hash.keys.each {|k| hash[k]=hash[k].to_s}; hash
end
I am trying this for the first time and am not sure I have quite achieved what i want to. I am pulling in data via a screen scrape as arrays and want to put them into a hash.
I have a model with columns :home_team and :away_team and would like to post the data captured via the screen scrape to these
I was hoping someone could quickly run this in a rb file
require 'open-uri'
require 'nokogiri'
FIXTURE_URL = "http://www.bbc.co.uk/sport/football/premier-league/fixtures"
doc = Nokogiri::HTML(open(FIXTURE_URL))
home_team = doc.css(".team-home.teams").map {|team| team.text.strip}
away_team = doc.css(".team-away.teams").map {|team| team.text.strip}
team_clean = Hash[:home_team => home_team, :away_team => away_team]
puts team_clean.inspect
and advise if this is actually a hash as it seems to be an array as i cant see the hash name being outputted. i would of expected something like this
{"team_clean"=>[{:home_team => "Man Utd", "Chelsea", "Liverpool"},
{:away_team => "Swansea", "Cardiff"}]}
any help appreciated
You actually get a Hash back. But it looks different from the one you expected. You expect a Hash inside a Hash.
Some examples to clarify:
hash = {}
hash.class
=> Hash
hash = { home_team: [], away_team: [] }
hash.class
=> Hash
hash[:home_team].class
=> Array
hash = { hash: { home_team: [], away_team: [] } }
hash.class
=> Hash
hash[:hash].class
=> Hash
hash[:hash][:home_team].class
=> Array
The "Hash name" as you call it, is never "outputed". A Hash is basically a Array with a different index. To clarify this a bit:
hash = { 0 => "A", 1 => "B" }
array = ["A", "B"]
hash[0]
=> "A"
array[0]
=> "A"
hash[1]
=> "B"
array[1]
=> "B"
Basically with a Hash you additionally define, how and where to find the values by defining the key explicitly, while an array always stores it with a numerical index.
here is the solution
team_clean = Hash[:team_clean => [Hash[:home_team => home_team,:away_team => away_team]]]
I have an array that contains dates and values. An example of how it might look:
[
{'1/1/2010' => 'aa'},
{'1/1/2010' => 'bb'},
{'1/2/2010' => 'cc'},
{'1/2/2010' => 'dd'},
{'1/3/2010' => 'ee'}
]
Notice that some of the dates repeat. I'm trying to output this in a table format and I only want to show unique dates. So I loop through it with the following code to get my desired output.
prev_date = nil
#reading_schedule.reading_plans.each do |plan|
use_date = nil
if plan.assigned_date != prev_date
use_date = plan.assigned_date
end
prev_date = plan.assigned_date
plan.assigned_date = use_date
end
The resulting table will then look something like this
1/1/2010 aa
bb
1/2/2010 cc
dd
1/3/2010 ee
This work fine but I am new to ruby and was wondering if there was a better way to do this.
Enumerable.group_by is a good starting point:
require 'pp'
asdf = [
{'1/1/2010' => 'aa'},
{'1/1/2010' => 'bb'},
{'1/2/2010' => 'cc'},
{'1/2/2010' => 'dd'},
{'1/3/2010' => 'ee'}
]
pp asdf.group_by { |n| n.keys.first }.map{ |a,b| { a => b.map { |c| c.to_a.last.last } } }
# >> [{"1/1/2010"=>["aa", "bb"]}, {"1/2/2010"=>["cc", "dd"]}, {"1/3/2010"=>["ee"]}]
Which should be a data structure you can bend to your will.
I don't know as though it's better, but you could group the values by date using (e.g.) Enumerable#reduce (requires Ruby >= 1.8.7; before that, you have Enumerable#inject).
arr.reduce({}) { |memo, obj|
obj.each_pair { |key, value|
memo[key] = [] if ! memo.has_key?(key);
memo[key] << value
}
memo
}.sort
=> [["1/1/2010", ["aa", "bb"]], ["1/2/2010", ["cc", "dd"]], ["1/3/2010", ["ee"]]]
You could also use Array#each to similar effect.
This is totally a job for a hash.
Create a hash and use the date as the hashkey and an empty array as the hashvalue.
Then accumulate the values from the original array in the hashvalue array
Lets say I have an Array of content_categories (content_categories = user.content_categories)
I now want to add every element belonging to a certain categorie to content_categories with the category as a key and the the content-item IDs as elements of a set
In PHP something like this is possible:
foreach ($content_categories as $key => $category) {
$contentsByCategoryIDArray = Category.getContents($category[id])
$content_categories[$key][$contentsByCategoryIDArray]
}
Is there an easy way in rails to do this?
Greets,
Nico
Your question isn't really a Rails question, it's a general Ruby programming question.
Your description isn't very clear, but from what I understand, you want to group IDs for common categories using a Hash. There are various other ways of doing this, but this is easy to understand::
ary = [
'cat1', {:id => 1},
'cat2', {:id => 2},
'cat1', {:id => 3}
]
hsh = {}
ary.each_slice(2) { |a|
key,category = a
hsh[key] ? hsh[key] << category[:id] : hsh[key] = [category[:id]]
}
hsh # => {"cat1"=>[1, 3], "cat2"=>[2]}
I'm using a simple Array with a category, followed by a simple hash representing some object instance, because it makes it easy to visualize. If you have a more complex object, replace the hash entries with those objects, and tweak how you access the ID in the ternary (?:) line.
Using Enumerable.inject():
hsh = ary.each_slice(2).inject({}) { |h,a|
key,category = a
h[key] ? h[key] << category[:id] : h[key] = [category[:id]]
h
}
hsh # => {"cat1"=>[1, 3], "cat2"=>[2]}
Enumerable.group_by() could probably shrink it even more, but my brain is fading.
I'd use Enumerable#inject
content_categories = content_categories_array.inject({}){ |memo, category| memo[category] = Category.get_contents(category); memo }
Hash[content_categories.map{|cat|
[cat, Category.get_contents(cat)]
}]
Not really the right answer, because you want IDs in your array, but I post it anyway, because it's nice and short, and you might actually get away with it:
content_categories.group_by(&:category)
content_categories.each do |k,v|
content_categories[k] = Category.getContents(v)
end
I suppose it's works
If i understand correctly, content_categories is an array of categories, which needs to be turned into a hash of categories, and their elements.
content_categories_array = content_categories
content_categories_hash = {}
content_categories_array.each do |category|
content_categories_hash[category] = Category.get_contents(category)
end
content_categories = content_categories_hash
That is the long version, which you can also write like
content_categories = {}.tap do |hash|
content_categories.each { |category| hash[category] = Category.get_contents(category) }
end
For this solution, content_categories must be a hash, not an array as you describe. Otherwise not sure where you're getting the key.
contents_by_categories = Hash[*content_categories.map{|k, v| [k, Category.getContents(v.id)]}]
I am wondering what is the best way to convert a json formatted key value pair to ruby hash with symbol as key:
example:
{ 'user': { 'name': 'foo', 'age': 40, 'location': { 'city' : 'bar', 'state': 'ca' } } }
==>
{ :user=>{ :name => 'foo', :age =>'40', :location=>{ :city => 'bar', :state=>'ca' } } }
Is there a helper method can do this?
using the json gem when parsing the json string you can pass in the symbolize_names option. See here: http://flori.github.com/json/doc/index.html (look under parse)
eg:
>> s ="{\"akey\":\"one\",\"bkey\":\"two\"}"
>> JSON.parse(s,:symbolize_names => true)
=> {:akey=>"one", :bkey=>"two"}
Leventix, thank you for your answer.
The Marshal.load(Marshal.dump(h)) method probably has the most integrity of the various methods because it preserves the original key types recursively.
This is important in case you have a nested hash with a mix of string and symbol keys and you want to preserve that mix upon decode (for instance, this could happen if your hash contains your own custom objects in addition to highly complex/nested third-party objects whose keys you cannot manipulate/convert for whatever reason, like a project time constraint).
E.g.:
h = {
:youtube => {
:search => 'daffy', # nested symbol key
'history' => ['goofy', 'mickey'] # nested string key
}
}
Method 1: JSON.parse - symbolizes all keys recursively => Does not preserve original mix
JSON.parse( h.to_json, {:symbolize_names => true} )
=> { :youtube => { :search=> "daffy", :history => ["goofy", "mickey"] } }
Method 2: ActiveSupport::JSON.decode - symbolizes top-level keys only => Does not preserve original mix
ActiveSupport::JSON.decode( ActiveSupport::JSON.encode(h) ).symbolize_keys
=> { :youtube => { "search" => "daffy", "history" => ["goofy", "mickey"] } }
Method 3: Marshal.load - preserves original string/symbol mix in the nested keys. PERFECT!
Marshal.load( Marshal.dump(h) )
=> { :youtube => { :search => "daffy", "history" => ["goofy", "mickey"] } }
Unless there is a drawback that I'm unaware of, I'd think Method 3 is the way to go.
Cheers
There isn't anything built in to do the trick, but it's not too hard to write the code to do it using the JSON gem. There is a symbolize_keys method built into Rails if you're using that, but that doesn't symbolize keys recursively like you need.
require 'json'
def json_to_sym_hash(json)
json.gsub!('\'', '"')
parsed = JSON.parse(json)
symbolize_keys(parsed)
end
def symbolize_keys(hash)
hash.inject({}){|new_hash, key_value|
key, value = key_value
value = symbolize_keys(value) if value.is_a?(Hash)
new_hash[key.to_sym] = value
new_hash
}
end
As Leventix said, the JSON gem only handles double quoted strings (which is technically correct - JSON should be formatted with double quotes). This bit of code will clean that up before trying to parse it.
Recursive method:
require 'json'
def JSON.parse(source, opts = {})
r = JSON.parser.new(source, opts).parse
r = keys_to_symbol(r) if opts[:symbolize_names]
return r
end
def keys_to_symbol(h)
new_hash = {}
h.each do |k,v|
if v.class == String || v.class == Fixnum || v.class == Float
new_hash[k.to_sym] = v
elsif v.class == Hash
new_hash[k.to_sym] = keys_to_symbol(v)
elsif v.class == Array
new_hash[k.to_sym] = keys_to_symbol_array(v)
else
raise ArgumentError, "Type not supported: #{v.class}"
end
end
return new_hash
end
def keys_to_symbol_array(array)
new_array = []
array.each do |i|
if i.class == Hash
new_array << keys_to_symbol(i)
elsif i.class == Array
new_array << keys_to_symbol_array(i)
else
new_array << i
end
end
return new_array
end
Of course, there is a json gem, but that handles only double quotes.
Another way to handle this is to use YAML serialization/deserialization, which also preserves the format of the key:
YAML.load({test: {'test' => { ':test' => 5}}}.to_yaml)
=> {:test=>{"test"=>{":test"=>5}}}
Benefit of this approach it seems like a format that is better suited for REST services...
The most convenient way is by using the nice_hash gem: https://github.com/MarioRuiz/nice_hash
require 'nice_hash'
my_str = "{ 'user': { 'name': 'foo', 'age': 40, 'location': { 'city' : 'bar', 'state': 'ca' } } }"
# on my_hash will have the json as a hash
my_hash = my_str.json
# or you can filter and get what you want
vals = my_str.json(:age, :city)
# even you can access the keys like this:
puts my_hash._user._location._city
puts my_hash.user.location.city
puts my_hash[:user][:location][:city]
If you think you might need both string and symbol keys:
JSON.parse(json_string).with_indifferent_access