Get processing instructions from XML file

[jacchr]

Hi Experts

I’m fairly new to the processing of XML files but have managed to extract most of the elements from my file.

But how do I get the processing instructions from the top of the XML file?

<?xml version="1.0" encoding="UTF-8" standalone="true"?>
<?vaxTimestamp 2021-02-01T20:05:13?>
<?vaxDocId 1ys6s72-8_7YJ6HGG6?>

I need to extract the vaxTimestamp and vaxDocId. If I loop through all the element of the XML file I can see they are of the type Processing Instructions.

Any ideas?

[NIVED_NAMBIAR (NIVED N)]

Hi @jacchr
You can try with regex
varTimestamp ReGEX PATTERN : (?<=vaxTimestamp ).*(?=[?>])

vaxDocId Regex pattern : (?<=vaxDocId ).*(?=[?>])

Regards
Nived N
Happy Automation

[jacchr]

Hi Nived_Nambiar

Thanks - but I’d rather avoid using RegEx now that it is an element that somehow can be referenced. I can use xmlDoc.FirstNode.ToString as well - but I’d like to be able to use the name/ID of the processing instruction instead like I do with all the other nodes/elements.

[ppr (Peter)]

@jacchr
having a sample string, parsing it to a xDocument with the help of Deserialize XML Activity (Package UiPath.WebAPI.Activities) has following result:

filtering all PIs

Access the PI Value:

Some samples on:
getting entire PI - SamplePI.toString
getting PI Value - SamplePI.Data
getting PI Name - SamplePI.Target

Also have a look on this activity:

[jacchr]

Thanks @ppr

I ended up using xmlDoc.Nodes.OfType(Of XProcessingInstruction).Cast(Of XProcessingInstruction).ToList which is very similar to your solution.

[jacchr]

@ppr

Would you by any chance know if it is possible to get .Data from from .Target matching a specific name?

E.g.

xDoc.Nodes().Where(Function(x) x.NodeType = XmlNodeType.ProcessingInstruction).Cast(Of XProcessingInstruction).First().Where(Function(y) y.Target = “vaxTimestamp”).Data

[ppr (Peter)]

@jacchr
the base type for LINQ is the IEnumerable. Have a look here:

LINQ API in .NET

@Dave gave us a good explanation on what it is here:

Explain Enumerable

@vivekktr To know what an enumerable is, you must understand the verb/action enumerate. The definition of enumerate is: “mention (a number of things) one by one.” An enumerable is just a read-only object that you can enumerate over. This means it is a collection of any type of variables that you can go through one-by-one. Since it is read-only, you can’t change the enumerable itself, you just read the information from it. This makes it the least resource intensive type of collection to iterate …

The nature of Where is returning us an IEnumerable(Of T) (just simplified) and can contain:

• 0
• 1
• multiple
  Items

So we have to ensure in your case, that we catch the data from 1 and only one element (think on no filter return and/or multiple catches).

For this we can work with DefaultIfEmpty and mixing Method and Query Syntax:

(From pi In xDoc.Nodes().Where(Function (x)  x.NodeType = XmlNodeType.ProcessingInstruction).Cast(Of XProcessingInstruction)
Where pi.Target.Equals(PIFilterKey)
Select pi).DefaultIfEmpty(New XProcessingInstruction("NoName","UNDEFINED")).First().Data

line1: fetch all PIs
line2: Filter all PIs with the name equal to the FilterKey
line3: for an empty result return a dummy PI, other wise return the found PIs, from this take the first PI and its Data

In case of we would expect multiple PI as a filer result we would return it e.g. as List/Array and process / evaluate later.

Output when found:

Output empty filter result: