Get elements with no textual values in XML in elixir

Questions / Help
,
1

I am trying to parse the following XML doc using SweetXML library.

<A>
    <B>23</B>
    <B>34</B>
    <B></B>
</A>

However when I try to parse the document using: xpath(~x"/A/B/text()"l)
I get the response ['23', '34']. Is there anyway I can get the list with nil value for the element having no text ? The response that I expect is: ['23', '34', nil].

2

As I understand your xpath you are explicitly asking for the text, but since there is non, you won’t get it in the result.

3

Thanks for the response. But is there any way around this ? It will be really helpful even if I can get the count of all B elements. That way I can compare with the length of the list and figure out how many such elements are there.

4

Why not just get the elements and parse them yourself?

5

Looking through the SweetXML docs I don’t see a way to get empty nodes so you’re probably best off asking the maintainer directly.

6

So I was able to find two methods of achieving the required result.

  1. stream_tags(xmldoc, :B) |> Stream.map( fn {:B, doc} -> doc |> SweetXml.xpath(~x"./text()") end) |> Enum.to_list

  2. xpath(xml, ~x"//A/B"l, number: ~x"text()") |> Enum.map(fn %{number: number} -> number end)
    Thanks everyone for your responses.

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7

The following XPath expression will return the string representation of your B elements:

/A/B/string()

or

/A/B/number()

if you’re expecting a number (NaN will be returned in the “empty” ,B/> case). You can test it here: https://www.freeformatter.com/xpath-tester.html#

Haven’t tested with SweetXML though.

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8

Thanks a lot. I found some solutions to the question and posted them here. They seem to be working.

9

For note, Meeseeks follows the same pattern for XPath queries:

iex(14)> doc = Meeseeks.parse(xmlString, :xml)
#Meeseeks.Document<{...}>

iex(15)> Meeseeks.all(doc, xpath("/A/B/text()"))
[#Meeseeks.Result<{ 23 }>, #Meeseeks.Result<{ 34 }>]

iex(16)> Meeseeks.all(doc, xpath("/A/B")) |> Enum.map(&Meeseeks.one(&1, xpath("text()")))
[#Meeseeks.Result<{ 23 }>, #Meeseeks.Result<{ 34 }>, nil]

iex(17)> Meeseeks.all(doc, xpath("/A/B")) |> Enum.map(&Meeseeks.text(&1))                
["23", "34", ""]
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