Class: OpenNebula::XMLElement

Inherits:
Object
  • Object
show all
Defined in:
lib/opennebula/xml_element.rb

Overview

The XMLElement class provides an abstraction of the underlying XML parser engine. It provides XML-related methods for the Pool and PoolElement classes

Direct Known Subclasses

HookLog, PoolElement, XMLPool

Class Method Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(xml = nil) ⇒ XMLElement

xml

_opaque xml object_ an xml object as returned by build_xml



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# File 'lib/opennebula/xml_element.rb', line 26

def initialize(xml=nil)
    @xml = xml
end

Class Method Details

.build_xml(xml, root_element) ⇒ Object

Builds a XML document

xml

String the XML document of the object

root_element

String Base xml element

return

XML object for the underlying XML engine



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# File 'lib/opennebula/xml_element.rb', line 56

def self.build_xml(xml, root_element)
    begin
        if NOKOGIRI
            doc = Nokogiri::XML(xml).xpath("/#{root_element}")
        else
            doc = REXML::Document.new(xml).root
        end
    rescue Exception => e
        return OpenNebula::Error.new(e.message)
    end

    return doc
end

Instance Method Details

#[](key) ⇒ String?

Extract a text element from the XML description of the PoolElement.

Examples:

vm['VID'] # gets VM id
vm['HISTORY/HOSTNAME'] # get the hostname from the history

Parameters:

  • key (String) —

    Xpath expression

Returns:

  • (String, nil) —

    If a text element is found, the element’s text value. Otherwise, an empty string or nil, depending on the backend



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# File 'lib/opennebula/xml_element.rb', line 86

def [](key)
    if NOKOGIRI
        element=@xml.xpath(key.to_s)

        return nil if element.size == 0
    else
        element=@xml.elements[key.to_s]

        return '' if element && !element.has_text?
    end

    element.text if element
end

#add_element(xpath, elems) ⇒ Object

Add a new element to the xml xpath::String xpath xpression where the elemente will be added elems::Hash Hash containing the pairs key-value to be included Examples:

add_element('VM', 'NEW_ITEM' => 'NEW_VALUE')
  <VM><NEW_ITEM>NEW_VALUE</NEW_ITEM>...</VM>

add_element('VM/TEMPLATE', 'V1' => {'X1' => 'A1', 'Y2' => 'A2'})
  <VM><TEMPLATE><V1><X1>A1</X1><Y2>A2</Y2>...</TEMPLATE></VM>



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# File 'lib/opennebula/xml_element.rb', line 119

def add_element(xpath, elems)
    elems.each { |key, value|
        if value.instance_of?(Hash)
            if NOKOGIRI
                elem = Nokogiri::XML::Node.new key, @xml.document
                value.each { |k2, v2|
                    child = Nokogiri::XML::Node.new k2, elem
                    child.content = v2
                    elem.add_child(child)
                }
                @xml.xpath(xpath.to_s).first.add_child(elem)
            else
                elem = REXML::Element.new(key)
                value.each { |k2, v2|
                    elem.add_element(k2).text = v2
                }
                @xml.elements[xpath].add_element(elem)
            end
        else
            if NOKOGIRI
                elem = Nokogiri::XML::Node.new key, @xml.document
                elem.content = value
                @xml.xpath(xpath.to_s).first.add_child(elem)
            else
                @xml.elements[xpath].add_element(key).text = value
            end
        end
    }
end

#attr(key, name) ⇒ Object

Gets an attribute from an element

key

String xpath for the element

name

String name of the attribute



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# File 'lib/opennebula/xml_element.rb', line 201

def attr(key,name)
    value = nil

    if NOKOGIRI
        element=@xml.xpath(key.to_s.upcase)
        if element.size == 0
            return nil
        end

        attribute = element.attr(name)

        value = attribute.text if attribute != nil
    else
        element=@xml.elements[key.to_s.upcase]

        value = element.attributes[name] if element != nil
    end

    return value
end

#delete_element(xpath) ⇒ Object

Delete an element from the xml xpath::String xpath expression that selects the elemnts to be deleted



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# File 'lib/opennebula/xml_element.rb', line 102

def delete_element(xpath)
    if NOKOGIRI
        @xml.xpath(xpath.to_s).remove
    else
        @xml.delete_element(xpath.to_s)
    end
end

#each(xpath_str, &block) ⇒ Object

Iterates over every Element in the XPath and calls the block with a a XMLElement

block

Block



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# File 'lib/opennebula/xml_element.rb', line 225

def each(xpath_str,&block)
    if NOKOGIRI
        @xml.xpath(xpath_str).each { |pelem|
            block.call XMLElement.new(pelem)
        }
    else
        @xml.elements.each(xpath_str) { |pelem|
            block.call XMLElement.new(pelem)
        }
    end
end

#each_xpath(xpath_str, &block) ⇒ Object 



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# File 'lib/opennebula/xml_element.rb', line 237

def each_xpath(xpath_str,&block)
    if NOKOGIRI
        @xml.xpath(xpath_str).each { |pelem|
            block.call pelem.text
        }
    else
        @xml.elements.each(xpath_str) { |pelem|
            block.call pelem.text
        }
    end
end

#element_xml(xpath) ⇒ Object

Returns the xml of an element



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# File 'lib/opennebula/xml_element.rb', line 289

def element_xml(xpath)
    if NOKOGIRI
        @xml.xpath(xpath).to_s
    else
        @xml.elements[xpath].to_s
    end
end

#has_elements?(xpath_str) ⇒ Boolean

Returns wheter there are elements for a given XPath

xpath_str

String XPath expression to locate the element

Returns:

  • (Boolean) 


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# File 'lib/opennebula/xml_element.rb', line 263

def has_elements?(xpath_str)
    if NOKOGIRI
        element = @xml.xpath(xpath_str.to_s.upcase)
        return element != nil && element.children.size > 0
    else
        element = @xml.elements[xpath_str.to_s]
        return element != nil && element.has_elements?
    end
end

#initialize_xml(xml, root_element) ⇒ Object

Initialize a XML document for the element

xml

String the XML document of the object

root_element

String Base xml element



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# File 'lib/opennebula/xml_element.rb', line 33

def initialize_xml(xml, root_element)
    @xml = XMLElement.build_xml(xml, root_element)

    if OpenNebula.is_error?(@xml)
        @xml = nil
    else
        if NOKOGIRI
            if @xml.size == 0
                @xml = nil
            end
        else
            if @xml.name != root_element
                @xml = nil
            end
        end
    end
    @xml
end

#name ⇒ Object 



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# File 'lib/opennebula/xml_element.rb', line 249

def name
    @xml.name
end

#retrieve_elements(filter) ⇒ Object

Gets an array of text from elements extracted using the XPATH expression passed as filter



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# File 'lib/opennebula/xml_element.rb', line 160

def retrieve_elements(filter)
    elements_array = Array.new

    if NOKOGIRI
        @xml.xpath(filter.to_s).each { |pelem|
            elements_array << pelem.text if pelem.text
         }
    else
        @xml.elements.each(filter.to_s) { |pelem|
            elements_array << pelem.text if pelem.text
        }
    end

    if elements_array.size == 0
        return nil
    else
        return elements_array
    end

end

#retrieve_xmlelements(xpath_str) ⇒ XMLElement

Iterates over every Element in the XPath and returns an array with XMLElements

Returns:



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# File 'lib/opennebula/xml_element.rb', line 184

def retrieve_xmlelements(xpath_str)
    collection = []
    if NOKOGIRI
        @xml.xpath(xpath_str).each { |pelem|
            collection << XMLElement.new(pelem)
        }
    else
        @xml.elements.each(xpath_str) { |pelem|
            collection << XMLElement.new(pelem)
        }
    end
    collection
end

#set_content(content) ⇒ Object

Update the content of the current doc



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# File 'lib/opennebula/xml_element.rb', line 150

def set_content(content)
    if NOKOGIRI
        @xml.content = content
    else
        @xml.text = content
    end
end

#template_like_str(root_element, indent = true, xpath_exp = nil) ⇒ Object

Returns elements in text form Known bug: For some older versions of REXML, the xpath expression

returns more nodes than expected
root_element

String base element

indent

Boolean indents the resulting string, default true

xpath_exp

String filter elements with a XPath



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# File 'lib/opennebula/xml_element.rb', line 303

def template_like_str(root_element, indent=true, xpath_exp=nil)
    if NOKOGIRI
        xml_template = @xml.xpath(root_element).to_s
        rexml        = REXML::Document.new(xml_template).root
    else
        rexml = @xml.elements[root_element]
    end

    if indent
        ind_enter = "\n"
        ind_tab   = '  '
    else
        ind_enter = ''
        ind_tab   = ' '
    end

    str = rexml.elements.collect(xpath_exp) {|n|
        next if n.class != REXML::Element

        str_line = ""

        if n.has_elements?
            str_line << "#{n.name}=[#{ind_enter}" << n.collect { |n2|

                next if n2.class != REXML::Element or !n2.has_text?

                str = "#{ind_tab}#{n2.name}=#{attr_to_str(n2.text)}"

            }.compact.join(",#{ind_enter}") << " ]"
        else
            next if !n.has_text?

            str_line << "#{n.name}=#{attr_to_str(n.text)}"
        end

        str_line
    }.compact.join("\n")

    return str
end

#template_str(indent = true) ⇒ Object

Returns the <TEMPLATE> element in text form

indent

Boolean indents the resulting string, default true



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# File 'lib/opennebula/xml_element.rb', line 275

def template_str(indent=true)
    template_like_str('TEMPLATE', indent)
end

#template_xml ⇒ Object

Returns the <TEMPLATE> element in XML form



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# File 'lib/opennebula/xml_element.rb', line 280

def template_xml
    if NOKOGIRI
        @xml.xpath('TEMPLATE').to_s
    else
        @xml.elements['TEMPLATE'].to_s
    end
end

#text ⇒ Object 



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# File 'lib/opennebula/xml_element.rb', line 253

def text
    if NOKOGIRI
        @xml.content
    else
        @xml.text
    end
end

#to_hash ⇒ Hash

Returns a hash representing the resource.

Returns:

  • (Hash) —

    a hash representing the resource



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# File 'lib/opennebula/xml_element.rb', line 365

def to_hash
    hash = {}

    if NOKOGIRI
        if @xml.instance_of?(Nokogiri::XML::NodeSet)
            @xml.each { |c|
                if c.element?
                    build_hash(hash, c)
                end
            }
        else
            build_hash(hash, @xml)
        end
    else
        build_hash(hash, @xml)
    end

    hash
end

#to_xml(pretty = false) ⇒ Object 



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# File 'lib/opennebula/xml_element.rb', line 347

def to_xml(pretty=false)
    if NOKOGIRI && pretty
        str = @xml.to_xml
    elsif REXML_FORMATTERS && pretty
        str = String.new

        formatter = REXML::Formatters::Pretty.new
        formatter.compact = true

        formatter.write(@xml,str)
    else
        str = @xml.to_s
    end

    return str
end

#xml_nil? ⇒ Boolean

Checks if the internal XML representation is valid

Returns:

  • (Boolean) 


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# File 'lib/opennebula/xml_element.rb', line 71

def xml_nil?
    return @xml.nil?
end