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class GenericFormatter < Formatter
attr_accessor :tag_name,:objects
def generate_xml
builder = Nokogiri::XML::Builder.new do |xml|
xml.send(tag_name.pluralize) {
objects.each do |obj|
xml.send(tag_name.singularize){
self.generate_obj_row obj,xml
}
end
}
end
builder.to_xml
end
def initialize tag_name,objects
self.tag_name = tag_name
self.objects = objects
end
def generate_obj_row obj,xml
obj.attributes.except("updated_at").map do |key,value|
xml.send(key, value)
end
xml.updated_at obj.updated_at.try(:strftime,"%m/%d/%Y %H:%M:%S") if obj.attributes.key?('updated_at')
end
end
In the above code, I have implemented the formatter where I have used the nokogiri XML Builder to generate the XML by manipulating the objects passing out inside the code.It's generated the faster XML when the data is not too large if data is larger like more than 10,000 records then It's slow down the XML to generate and takes at least 50-60 seconds.
Problem: Is there any way to generate the XML faster, I have tried XML Builders on view as well but did n't work.How can I generate the XML Faster? Should the solution be an application on rails 3 and suggestions to optimized above code?
973
Your main problem is processing everything in one go instead of splitting your data into batches. It all requires a lot of memory, first to build all those ActiveRecord models and then to build memory representation of the whole xml document. Meta-programming is also quite expensive (I mean those send methods).
Take a look at this code:
class XmlGenerator
attr_accessor :tag_name, :ar_relation
def initialize(tag_name, ar_relation)
@ar_relation = ar_relation
@tag_name = tag_name
end
def generate_xml
singular_tag_name = tag_name.singularize
plural_tag_name = tag_name.pluralize
xml = ""
xml << "<#{plural_tag_name}>"
ar_relation.find_in_batches(batch_size: 1000) do |batch|
batch.each do |obj|
xml << "<#{singular_tag_name}>"
obj.attributes.except("updated_at").each do |key, value|
xml << "<#{key}>#{value}</#{key}>"
end
if obj.attributes.key?("updated_at")
xml << "<updated_at>#{obj.updated_at.strftime('%m/%d/%Y %H:%M:%S')}</updated_at>"
end
xml << "</#{singular_tag_name}>"
end
end
xml << "</#{tag_name.pluralize}>"
xml
end
end
# example usage
XmlGenerator.new("user", User.where("age < 21")).generate_xml
Major improvements are:
I tested it on over 60k records. It took around 40 seconds to generate such xml document.
There is much more that can be done to improve this even further, but it all depends on your application.
Here are some ideas:
76
The Nokogiri gem has a nice interface for creating XML from scratch,
Nokogiri is a wrapper around libxml2.
Gemfile gem 'nokogiri' To generate xml simple use the Nokogiri XML Builder like this
xml = Nokogiri::XML::Builder.new { |xml|
xml.body do
xml.test1 "some string"
xml.test2 890
xml.test3 do
xml.test3_1 "some string"
end
xml.test4 "with attributes", :attribute => "some attribute"
xml.closing
end
}.to_xml
output
<?xml version="1.0"?>
<body>
<test1>some string</test1>
<test2>890</test2>
<test3>
<test3_1>some string</test3_1>
</test3>
<test4 attribute="some attribute">with attributes</test4>
<closing/>
</body>
Demo: http://www.jakobbeyer.de/xml-with-nokogiri
1
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