Get xml node name

Elastic Stack Logstash
1

Hello,
I am little lost with one problem when parsing xml files to ES with Logstash. Due to unfortunate xml structure which I can't change, I need to get string name of specific nodes. Example of xml structure:

<Parent>
<FirstName>XXXX</FirstName>
<SecondName>XXXX</SecondName>
<WhateverName>XXXX</ThirdName>
</Parent>

Names of the "Name fields" may vary and I need to get list of their names to one array field which should be pushed to Elastic like this:

ElasticField = {FirstName, SecondName, WhateverName, etc.}

For text() values I use xml filter and xpath which works great. Is there any easy way, how to do it?

Thank you

2

The name() function returns the name of the first element it is given. If there is a known limit to the number of name elements you could do

    xml {
        source => "message"
        store_xml => false
        xpath => {
            "name(/Parent/*[1])" => "[@metadata][names][0]"
            "name(/Parent/*[2])" => "[@metadata][names][1]"
            "name(/Parent/*[3])" => "[@metadata][names][2]"
            "name(/Parent/*[4])" => "[@metadata][names][3]"
            "name(/Parent/*[5])" => "[@metadata][names][4]"
        }
    }

This will create a hash of arrays of arrays

    "names" => {
        "1" => [
            [0] "SecondName"
        ],
        "4" => [
            [0] ""
        ],
        ...

Why they are out of order (and Ruby hashes are ordered) I have no idea. To convert that to an array you can use a ruby filter. If you do not care about the order then

            names = event.get("[@metadata][names]")
            nameList = []
            names.each { |k, v|
                if v[0] != ""
                    nameList << v[0]
                end
            }
            event.set("nameElements", nameList)

will get you

"nameElements" => [
    [0] "SecondName",
    [1] "FirstName",
    [2] "WhateverName"
],

If you do care about order then

            nameList = []
            names = event.get("[@metadata][names]")
            (0..4).each { |x|
                if names[x.to_s][0] != ""
                    nameList << names[x.to_s][0]
                end
            }
            event.set("nameElements", nameList)

will get you

"nameElements" => [
    [0] "FirstName",
    [1] "SecondName",
    [2] "WhateverName"
],

I cannot think of a way to deal with an arbitrary number of elements other than setting store_xml to true and using a ruby filter to extract the element names.

3

Thanks, that helped a lot.

However, I have realized that all the nodes I am trying to get their names have the same children structure. Is there any way, how to approach the problem from parent-children perspective?

I am trying to use this:
'xpath => {"name(//time//parent::node())" => "NodeNamesArray"}'

... but it only gets me the first parent node name the parser finds. Is there any other way?

Thank you very much.

4

The name function is documented as returning the name of the first element it is given.

5

This topic was automatically closed 28 days after the last reply. New replies are no longer allowed.