Nodes with the same value are mixed up

[Leonti]

Hi!
I'm having a weird issue with targeting nodes that I want to replace, given the following snippet:

import scala.xml._
import advxml.syntax.traverse.try_._
import advxml.syntax.transform._
import advxml.instances.transform._
import scala.util._
import cats.implicits._

val doc = XML.loadString("""
<charts>
  <chart>
    <title>chart-0</title>
    <entries>
      <entry idx="0">
        <v>13</v>
      </entry>
    </entries>
  </chart>
  <chart>
    <title>chart-1</title>
    <entries>
      <entry idx="0">
        <v>12</v>
      </entry>
    </entries>
  </chart>  
</charts>
""")

def toEntries(root: NodeSeq): NodeSeq = (root \ "chart" filter hasImmediateChild("title", text(_ == "chart-1"))) \ "entries"

val rule = $(r => (toEntries(r) \ "entry" filter attrs("idx" -> (_ == "0"))) \ "v" ) ==> Replace(_ => <v>11</v>) 

val result: Try[NodeSeq] = doc.transform[Try](rule)

println(result.toOption.get)

It will output this:

<charts>
   <chart>
      <title>chart-0</title>
      <entries>
         <entry idx="0">
            <v>13</v>
         </entry>
      </entries>
   </chart>
   <chart>
      <title>chart-1</title>
      <entries>
         <entry idx="0">
            <v>11</v>
         </entry>
      </entries>
   </chart>
</charts>

https://scastie.scala-lang.org/JRM25U76S6yXpcIV6ZuDug
It correctly found entries of a chart which has chart-1 as a title and then replaced it.

But as soon as I make the original values to be the same number:

val doc = XML.loadString("""
<charts>
  <chart>
    <title>chart-0</title>
    <entries>
      <entry idx="0">
        <v>12</v>
      </entry>
    </entries>
  </chart>
  <chart>
    <title>chart-1</title>
    <entries>
      <entry idx="0">
        <v>12</v>
      </entry>
    </entries>
  </chart>  
</charts>
""")

it will replace the entry under chart-0, not chart-1 as expected:

<charts>
   <chart>
      <title>chart-0</title>
      <entries>
         <entry idx="0">
            <v>11</v>
         </entry>
      </entries>
   </chart>
   <chart>
      <title>chart-1</title>
      <entries>
         <entry idx="0">
            <v>12</v>
         </entry>
      </entries>
   </chart>
</charts>

https://scastie.scala-lang.org/KBkU87D6T4GhNlkDq3rWjQ

Looks like it's finding the element first, so in this case <v>12</v> and then using it for replacement, so if you have 2 identical elements bu with different paths it will replace the first one.

Or maybe I'm not using it correctly?
By they way, apart from this issue the library is a joy to use, thanks!

[geirolz]

Hi @Leonti thanks for your feedback :)
I'm investigating about this problem, i let you know as soon as possible.

P.S. Special thanks for scastie examples.

[geirolz]

@SethTisue what do you think about this problem ?

Currently in my XmlTransformer class i create a standard RewriteRule instance and, if parameter is equals to the target(the node to edit) i apply my function. The problem is that the node hasn't an unique ID and the structure is an unidirectional tree(i can't check his parent) so in this case i match the both the nodes.

[geirolz]

I've just opened an issue on scala-xml project for this problem.
scala/scala-xml#403

[SethTisue]

@geirolz sorry, no opinion, I don't know this API, either in this repo or over in scala-xml

[geirolz]

Hi @Leonti finally i've resolved this bug.
I'm going to release a new draft version 2.1.0-RC1, if you what you can try it and give me a feedback , your help is very important for me.

Thanks for the support.

[Leonti]

Hi @geirolz!
That's awesome news! Thanks a lot!
Sorry for the late reply, didn't have a chance to try it out before.
I like the new interface, where XmlZoom is a case class :)

I see that \\ is not supported - any way I can replace it with existing \, \+, \++, | combinators?

Thanks again,
Leonti

[geirolz]

@Leonti Yes unfortunately currently \\ is not supported, i'm working on it.

• \ traverse the document down to the immediate child with specified label
• \+ and \++ is used to combine respectively one and more XmlZoom.
• | is just an alias to filter method

So, for answer to your question:

any way I can replace it with existing , +, ++, | combinators?

No, the only way to traverse the document currently is using \, you need to "map" the full path to the node you want. I know that this is a regression but i prefered fix a runtime bug , i'm working on a solution to reintroduce \\ the operator.

Is your bug fixed with these changes ?

[Leonti]

Hi @geirolz!

Yes, definitely the right call with fixing the bug first and then introducing the missing functionality.

Haven't had a chance to update the library in my code to see if it fixed the bug (I'm using a workaround for now - just making sure all the values are unique).
Will try to get to it next week, but by looking at your code it looks like it's going to fix it :)

Thanks a lot!