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While parsing an indented XML, non-significant white space text nodes are created from the white spaces between a closing and an opening tag. For example, from the following XML:
<note>
<to>Tove</to>
<from>Jani</from>
<heading>Reminder</heading>
<body>Don't forget me this weekend!</body>
</note>
whose string representation is as follows,
"<note>\n <to>Tove</to>\n <from>Jani</from>\n <heading>Reminder</heading>\n <body>Don't forget me this weekend!</body>\n</note>\n"
the following Document is created:
#(Document:0x3fc07e4540d8 {
name = "document",
children = [
#(Element:0x3fc07ec8629c {
name = "note",
children = [
#(Text "\n "),
#(Element:0x3fc07ec8089c {
name = "to",
children = [ #(Text "Tove")]
}),
#(Text "\n "),
#(Element:0x3fc07e8d8064 {
name = "from",
children = [ #(Text "Jani")]
}),
#(Text "\n "),
#(Element:0x3fc07e8d588c {
name = "heading",
children = [ #(Text "Reminder")]
}),
#(Text "\n "),
#(Element:0x3fc07e8cf590 {
name = "body",
children = [ #(Text "Don't forget me this weekend!")]
}),
#(Text "\n")]
})]
})
Here, there are lots of white space nodes of type Nokogiri::XML::Text.
I would like to count the children of each node in a Nokogiri XML Document, and access the first or last child, excluding non-significant white spaces. I wish not to parse them, or distinguish between those and significant text nodes such as those inside the element <to>, like "Tove". Here is an rspec of what I am looking for:
require 'nokogiri'
require_relative 'spec_helper'
xml_text = <<XML
<note>
<to>Tove</to>
<from>Jani</from>
<heading>Reminder</heading>
<body>Don't forget me this weekend!</body>
</note>
XML
xml = Nokogiri::XML(xml_text)
def significant_nodes(node)
return 0
end
describe "Stackoverflow Question" do
it "should return the number of significant nodes in nokogiri." do
expect(significant_nodes(xml.css('note'))).to eq 4
end
end
I want to know how to create the significant_nodes function.
If I change the XML to:
<note>
<to>Tove</to>
<from>Jani</from>
<heading>Reminder</heading>
<body>Don't forget me this weekend!</body>
<footer></footer>
</note>
then when I create the Document, I still would like the footer represented; using config.noblanks is not an option.
705
You can use the NOBLANKS option for parsing the XML string, consider this example:
require 'nokogiri'
string = "<foo>\n <bar>bar</bar>\n</foo>"
puts string
# <foo>
# <bar>bar</bar>
# </foo>
document_with_blanks = Nokogiri::XML.parse(s)
document_without_blanks = Nokogiri::XML.parse(s) do |config|
config.noblanks
end
document_with_blanks.root.children.each { |child| p child }
#<Nokogiri::XML::Text:0x3ffa4e153dac "\n ">
#<Nokogiri::XML::Element:0x3fdce3f78488 name="bar" children=[#<Nokogiri::XML::Text:0x3fdce3f781f4 "bar">]>
#<Nokogiri::XML::Text:0x3ffa4e15335c "\n">
document_without_blanks.root.children.each { |child| p child }
#<Nokogiri::XML::Element:0x3f81bef42034 name="bar" children=[#<Nokogiri::XML::Text:0x3f81bef43ee8 "bar">]>
The NOBLANKS shouldn't remove empty nodes:
doc = Nokogiri.XML('<foo><bar></bar></foo>') do |config|
config.noblanks
end
doc.root.children.each { |child| p child }
#<Nokogiri::XML::Element:0x3fad0fafbfa8 name="bar">
As OP pointed out the documentation on the Nokogiri website (and also on the libxml website) about the parser options is quite cryptic, following a specification of the behaviour ot the NOBLANKS option:
require 'rspec/autorun'
require 'nokogiri'
def parse_xml(xml_string)
Nokogiri.XML(xml_string) { |config| config.noblanks }
end
describe "Nokogiri NOBLANKS parser option" do
it "removes whitespace nodes if they have siblings" do
doc = parse_xml("<root>\n <child></child></root>")
expect(doc.root.children.size).to eq(1)
expect(doc.root.children.first).to be_kind_of(Nokogiri::XML::Node)
end
it "doesn't remove whitespaces nodes if they have no siblings" do
doc = parse_xml("<root>\n </root>")
expect(doc.root.children.size).to eq(1)
expect(doc.root.children.first).to be_kind_of(Nokogiri::XML::Text)
end
it "doesn't remove empty nodes" do
doc = parse_xml('<root><child></child></root>')
expect(doc.root.children.size).to eq(1)
expect(doc.root.children.first).to be_kind_of(Nokogiri::XML::Node)
end
end
You can create a query that only returns element nodes, and ignores text nodes. In XPath, * only returns elements, so the query could look like (querying the whole doc):
doc.xpath('//note/*')
or if you want to use CSS:
doc.css('note > *')
If you want to implement your significant_nodes method, you would need to make the query relative to the node passed in:
def significant_nodes(node)
node.xpath('./*').size
end
I don’t know how to do a relative query with CSS, you might need to stick with XPath.
43
Nokogiri's noblanks config option doesn't remove all whitespace Text nodes when they have siblings:
describe "Nokogiri NOBLANKS parser option" do
it "doesn't remove whitespace Text nodes if they're surrounded by non-whitespace Text node siblings" do
doc = parse_xml("<root>1 <two></two> \n <three></three> \n <four></four> 5</root>")
children = doc.root.children
expect(children.size).to_not eq(5)
expect(children.size).to eq(7) #Because the two newline Text nodes are not ignored
expect(doc.root.children.first).to be_kind_of(Nokogiri::XML::Node)
end
end
I'm not sure why Nokogiri was programmed to work that way. I think it would be better to either ignore all whitespace Text nodes are don't ignore any Text nodes.
2
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