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Help with sequences and Xml parsing
f#parsing

Hi
I have a piece of XML that looks like

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<A>
   <B>
       <C>
            <Deal foo="1" bar="2"/>
       </C>
        <C>
               <Deal foo="1" bar="2"/>
       </C>
       <C>
            <Deal foo="1" bar="2"/>
       </C>
    </B>
</A>

I have an active pattern that matches "Deal" objects , something along the lines of

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let (|Element|_|) name (inp : #XmlNode) =
        if inp.Name = name then Some (inp) else None
let rec (|Deal|) (inp :#XmlNode) = match inp with | Element "Deal" inp -> Some(DObject(....))

However I can't figure out a clean way, given the root node "A" to disregard any child elements until one gets to a "Deals"
This following works, but I'm sure there's something cleaner (more functional!)

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// Utilities function to strip away the layers from the response object unti
// we get to a "Deal" element. Returns a sequence of Deals that can then be
// analysed further
let findDeals (inp : #XmlNode) =
	if inp.Name = "A" then
		let chresponses = inp.ChildNodes.[0] // Assumption : only one child of A <- BAD
		let chresponse = seq {for r in chresponses -> r} // Many children of "B"
		Seq.map (fun (x :#XmlNode) -> 
			let deal = x.ChildNodes.[0] // C only has one child which is a Deal <- assumption but not ideal
			match deal with
			| Deal y -> y) chresponse
	else
		failwith "Not a know node"

Any help would be appreciated.
Regards
Ronnie

.

[...] I can't figure out a clean way, given the root node "A" to disregard any child elements until one gets to a "Deals"

This following works, but I'm sure there's something cleaner (more functional!)

Hey Ronnie, give this a try:

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#light
open System.Xml;

type DObject( xml : XmlNode ) =
    let foo = Int32.of_string (xml.Attributes.["foo"]).Value
    let bar = Int32.of_string (xml.Attributes.["bar"]).Value
    member x.foo = foo
    member x.bar = bar

let (|Element|_|) name (inp:#XmlNode) =
    if inp.Name = name
    then Some(inp)
    else None
    
let (|Deal|) (inp:#XmlNode) =
    match inp with
    | Element "Deal" inp -> Some(DObject(inp))
    | _ -> None

let xml = @"<A>
               <B>
                   <C>
                      <Deal foo='1' bar='2'/>
                   </C>
                   <C>
                          <Deal foo='1' bar='2'/>
                   </C>
                   <C>
                        <Deal foo='1' bar='2'/>
                   </C>
                </B>
            </A>"

let dom = System.Xml.XmlDocument()
do dom.LoadXml( xml );
let deals = { for deal in dom.GetElementsByTagName("Deal") -> deal }
            |> Seq.choose (function node -> match node with Deal d -> d )

deals
|> Seq.iter (fun deal ->
    printfn "Deal foo=%i bar=%i" (deal.foo) (deal.bar)
    )
By on 6/9/2008 7:05 PM ()

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