how to get all attributes in an element

Naresh Ramaswamy · Mar 10, 2009

hi,

I am using REXML

I want to get all the attributes under an element. Just imagine that I
know the element name but not the attribute names.

say <element att1="x" att2="y" att3="3"/> and so on as many attributes
that can be.

I need to get all the attributes under the element. How shall I do it.

I looked into REXML doc that provides
"doc.root.attributes.each {|name, value| puts name+" => "+value }"

But I am able to use this only on root element, and does not work on
child or subchild elements.

Please let me know how can I do that.

Regards,
Naresh

7stud -- · Mar 10, 2009

Naresh said:
hi,

I am using REXML

I want to get all the attributes under an element. Just imagine that I
know the element name but not the attribute names.

say <element att1="x" att2="y" att3="3"/> and so on as many attributes
that can be.

I need to get all the attributes under the element. How shall I do it.

I looked into REXML doc that provides
"doc.root.attributes.each {|name, value| puts name+" => "+value }"

But I am able to use this only on root element, and does not work on
child or subchild elements.

Please let me know how can I do that.

Regards,
Naresh

require 'rexml/document'
include REXML

xml = <<ENDSTRING
<?xml version="1.0" encoding="ISO-8859-1"?>
<note>
<to>Tove</to>
<from>Jani</from>
<heading>Reminder</heading>
<body att1="x" att2="y">Don't forget me this weekend!</body>
</note>
ENDSTRING

doc = Document.new xml

el_name = "body"
matching_elements = XPath.match(doc, "//#{el_name}")

matching_elements.each do |el|
attrs = el.attributes
attrs.each_key do |key|
puts attrs[key]
end
end

--output:--
x
y

Naresh Ramaswamy · Mar 11, 2009

--output:--

x
y

Thank you for the solution, it almost worked to me, but when I apply it
on my xml document I am getting the output from reverse order, why so?

<?xml version="1.0" encoding="iso-8859-1"?>

<TEST_SCRIPT name='Basetest'>
<TXN value = '1'>
<SEND request='INVITE' sdp='true'>
<REMOVE_1 header='req_line' mname='InVIte'
uri='tel:[email protected]'/>
<ADD_1 header='to' dname='ister'/>
<REMOVE_2 header='call_id' />
</SEND>
</TXN>
</TEST_SCRIPT>

I applied the code for the element "REMOVE_1" and observe the following
as the output.

-----output------
tel:[email protected]
InVIte
req_line

Phlip · Mar 11, 2009

Naresh said:
Thank you for the solution, it almost worked to me, but when I apply it
on my xml document I am getting the output from reverse order, why so?

<REMOVE_1 header='req_line' mname='InVIte'
uri='tel:[email protected]'/>

I applied the code for the element "REMOVE_1" and observe the following
as the output.

-----output------
tel:[email protected]
InVIte
req_line
-----------------

XML has a concept of document order, but not of attribute order within one tag.
XML readers are (apparently) not required to remember there order.

Next, the attributes come in a Hash, and this has a BUG (!) which will be FIXED
(!) in the next Ruby versions. It can't preserve the order you inserted its keys.

Until then, your own code must put the keys into the order you need. Try

element.attributes.to_a.sort

to put them into asciibetic order, for example.

7stud -- · Mar 12, 2009

Phlip said:
Naresh Ramaswamy wrote:

Next, the attributes come in a Hash, and this has a BUG (!) which will
be FIXED
(!) in the next Ruby versions. It can't preserve the order you inserted
its keys.

Hmm. A bug is when a language doesn't operate as described:

----
p. 46, pickaxe 2:

[a hash's] elements are not ordered, so you can not easily use a hash as
a stack or a queue.

p. 492

The order in which keys and/or values are returned by the various
iterators over hash contents may seem arbitrary and will generally not
be in insertion order.
----

$ ri Hash

------------------------------------------------------------ Class: Hash
A +Hash+ is a collection of key-value pairs. It is similar to an
+Array+, except that indexing is done via arbitrary keys of any
object type, not an integer index. The order in which you traverse
a hash by either key or value may seem arbitrary, and will
generally not be in the insertion order.

Hashes have a _default value_ that is returned when accessing keys
that do not exist in the hash. By default, that value is +nil+.

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how to get all attributes in an element

Naresh Ramaswamy

7stud --

Naresh Ramaswamy

Phlip

7stud --

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