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

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



25
26
27
# File 'lib/opennebula/xml_element.rb', line 25

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



55
56
57
58
59
60
61
62
63
64
65
66
67
# File 'lib/opennebula/xml_element.rb', line 55

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



85
86
87
88
89
90
91
92
93
94
95
96
97
# File 'lib/opennebula/xml_element.rb', line 85

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>


118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
# File 'lib/opennebula/xml_element.rb', line 118

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



191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
# File 'lib/opennebula/xml_element.rb', line 191

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



101
102
103
104
105
106
107
# File 'lib/opennebula/xml_element.rb', line 101

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



215
216
217
218
219
220
221
222
223
224
225
# File 'lib/opennebula/xml_element.rb', line 215

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



227
228
229
230
231
232
233
234
235
236
237
# File 'lib/opennebula/xml_element.rb', line 227

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



279
280
281
282
283
284
285
# File 'lib/opennebula/xml_element.rb', line 279

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)


253
254
255
256
257
258
259
260
261
# File 'lib/opennebula/xml_element.rb', line 253

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



32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
# File 'lib/opennebula/xml_element.rb', line 32

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

#nameObject



239
240
241
# File 'lib/opennebula/xml_element.rb', line 239

def name
    @xml.name
end

#retrieve_elements(filter) ⇒ Object

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



150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
# File 'lib/opennebula/xml_element.rb', line 150

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:



174
175
176
177
178
179
180
181
182
183
184
185
186
# File 'lib/opennebula/xml_element.rb', line 174

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

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

Returns elements in text form

root_element

String base element

indent

Boolean indents the resulting string, default true

xpath_exp

String filter elements with a XPath



291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
# File 'lib/opennebula/xml_element.rb', line 291

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



265
266
267
# File 'lib/opennebula/xml_element.rb', line 265

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

#template_xmlObject

Returns the <TEMPLATE> element in XML form



270
271
272
273
274
275
276
# File 'lib/opennebula/xml_element.rb', line 270

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

#textObject



243
244
245
246
247
248
249
# File 'lib/opennebula/xml_element.rb', line 243

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

#to_hashHash

Returns a hash representing the resource.

Returns:

  • (Hash)

    a hash representing the resource



353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
# File 'lib/opennebula/xml_element.rb', line 353

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



335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
# File 'lib/opennebula/xml_element.rb', line 335

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)


70
71
72
# File 'lib/opennebula/xml_element.rb', line 70

def xml_nil?
    return @xml.nil?
end