XML Serialization with F#

Question

I'm a total F# n00b, so I hope i give you enough information. I created a class called record. I create several instances of this class with data from our database. I then add each record to a list of records. i want to make an xml document with those records.

//this is the record data type i created. I also created a sender and recipient data
//type but those are probably not neccessary to understand the issue
type record(id:int, sender:sender, ?recipients: recipient list ) =  
    let mutable id: int = id
    let mutable typ = "Message"
    let mutable creation = creation()
    let mutable sender  = sender
    let mutable recipients = recipients

    [<XmlIgnore()>] 
    [<XmlArrayAttribute("recipients")>]
    [<XmlArrayItem(typeof<recipient>, ElementName = "recipient")>]
    member this.Recipients with get() = recipients and set v = recipients <- v

    public new() =
        record(12180, sender(12180,"Joe","Plumber","[email protected]"), list.Empty)

    [<XmlElement("id")>] 
    member this.Id with get() = id and set v = id <- v

    [<XmlElement("creation")>] 
    member this.Creation with get() = creation and set v = creation <- v

    [<XmlElement("sender")>] 
    member this.Sender with get() = sender and set v = sender <- v

//i later call this:
 let xmlSerializer = XmlSerializer(typeof<record list>)

I then get this error message at runtime:

There was an error reflecting type 'Microsoft.FSharp.Collections.FSharpList`1[XXXX.Compliance.YYYYY.record]'. //x's and y's used to protect the innocent.

Answer 1

Caveat: I am not sure.

I think that some F# types (like 'list') do not admit serialization with the XmlSerializer (e.g. that serialization technology requires types with field setters or public default constructors or some such nonsense). I think some options that might immediately unblock you include

• change from using F# lists to using .NET arrays (record list -> record [], etc)
• (possibly) use the DataContractSerializer instead of XmlSerializer, as the DCS does not require as much from the type (I forget if it works with F# lists or not)
• probably something else I have forgotten

Hopefully someone else more immediately familiar with .NET serialization technologies can provide a more definitive answer.