F# SEPA XML Serialization throws an exception

Question

I am creating a converter to SEPA XML in F# using the .NET XML Serializer:

[]
[]
type InitiatingParty = {
    []
    Name: string
}

[]
[]
type GroupHeader = {
    []
    MessageId: string

    []
    CreationDateTime: string

    []
    TransactionCount: string

    []
    ControlSum: string

    []
    InitiatingParty: InitiatingParty
}

[]
[]
type ServiceLevel = {
    []
    Code: string
}

[]
[]
type PaymentTypeInformation = {
    []
    ServiceLevel: ServiceLevel
}

[]
[]
type Debtor = {
    []
    Name: string
}

[]
[]
type Id = {
    []
    Iban: string
}

[]
[]
type DebtorAccount = {
    []
    Id: Id
    []
    Currency: string
}

[]
[]
type FinancialInstitutionId = {
    []
    Bic: string
}

[]
[]
type DebtorAgent = {
    []
    FinancialInstitutionId: FinancialInstitutionId
}

[]
[]
type PaymentIdentification = {
    []
    EndToEndId: string
}

[]
[]
type InstructedAmount = {
    []
    Currency: string
    []
    Text: string
}

[]
[]
type Amount = {
    []
    InstructedAmount: InstructedAmount
}

[]
[]
type CreditorAgent = {
    []
    FinancialInstitutionId: FinancialInstitutionId
}

[]
[]
type Creditor = {
    []
    Name: string
}

[]
[]
type CreditorAccount = {
    []
    Id: Id
}

[]
[]
type RemittanceInformation = {
    []
    Unstructured: string
}

[]
[]
type CreditTransferTransactionInformation = {
    []
    PaymentIdentification: PaymentIdentification

    []
    Amount: Amount

    []
    CreditorAgent: CreditorAgent

    []
    Creditor: Creditor

    []
    CreditorAccount: CreditorAccount

    []
    RemittanceInformation: RemittanceInformation
}

[]
[]
type PaymentInformation = {
    []
    PaymentInformationId: string

    []
    PaymentMethod: string 

    []
    TransactionCount: string

    []
    ControlSum: string

    []
    PaymentTypeInformation: PaymentTypeInformation 

    []
    RequestedExecutionDate: string

    []
    Debtor: Debtor 

    []
    DebtorAccount: DebtorAccount

    []
    DebtorAgent: DebtorAgent 

    []
    ChargeBearer: string 

    []
    CreditTransferTransactionInformation: List  
}

[]
[]
type CustomerCreditTransferInitialization = {
    []
    GroupHeader: GroupHeader 

    []
    PaymentInformation: PaymentInformation 
}

[]
[]
type Document = {
    []
    CustomerCreditTransferInitialization: CustomerCreditTransferInitialization 

    []
    Xsi: string 

    []
    Xmlns: string
}

When using the serializer it crash:

[]
let main argv =
    let xmlSerializer = new XmlSerializer(typeof)
    return 0

The exception I have:

System.InvalidOperationException: There was an error reflecting type 'Program.Document'. ---> System.InvalidOperationException: There was an error reflecting property 'CustomerCreditTransferInitialization'. ---> System.InvalidOperationException: There was an error reflecting type 'Program.CustomerCreditTransferInitialization'. ---> System.InvalidOperationException: There was an error reflecting property 'PaymentInformation'. ---> System.InvalidOperationException: There was an error reflecting type 'Program.PaymentInformation'. ---> System.InvalidOperationException: There was an error reflecting property 'CreditTransferTransactionInformation'. ---> System.NullReferenceException: Object reference not set to an instance of an object.
   at System.Xml.Serialization.TypeScope.GetTypeDesc(Type type, MemberInfo source, Boolean directReference, Boolean throwOnError)
   at System.Xml.Serialization.XmlReflectionImporter.ImportAccessorMapping(MemberMapping accessor, FieldModel model, XmlAttributes a, String ns, Type choiceIdentifierType, Boolean rpc, Boolean openModel, RecursionLimiter limiter)
   at System.Xml.Serialization.XmlReflectionImporter.ImportFieldMapping(StructModel parent, FieldModel model, XmlAttributes a, String ns, RecursionLimiter limiter)
   at System.Xml.Serialization.XmlReflectionImporter.InitializeStructMembers(StructMapping mapping, StructModel model, Boolean openModel, String typeName, RecursionLimiter limiter)
   --- End of inner exception stack trace ---
   at System.Xml.Serialization.XmlReflectionImporter.InitializeStructMembers(StructMapping mapping, StructModel model, Boolean openModel, String typeName, RecursionLimiter limiter)
   at System.Xml.Serialization.XmlReflectionImporter.ImportStructLikeMapping(StructModel model, String ns, Boolean openModel, XmlAttributes a, RecursionLimiter limiter)
   at System.Xml.Serialization.XmlReflectionImporter.ImportTypeMapping(TypeModel model, String ns, ImportContext context, String dataType, XmlAttributes a, Boolean repeats, Boolean openModel, RecursionLimiter limiter)
   --- End of inner exception stack trace ---
   at System.Xml.Serialization.XmlReflectionImporter.ImportTypeMapping(TypeModel model, String ns, ImportContext context, String dataType, XmlAttributes a, Boolean repeats, Boolean openModel, RecursionLimiter limiter)
   at System.Xml.Serialization.XmlReflectionImporter.ImportAccessorMapping(MemberMapping accessor, FieldModel model, XmlAttributes a, String ns, Type choiceIdentifierType, Boolean rpc, Boolean openModel, RecursionLimiter limiter)
   at System.Xml.Serialization.XmlReflectionImporter.ImportFieldMapping(StructModel parent, FieldModel model, XmlAttributes a, String ns, RecursionLimiter limiter)
   at System.Xml.Serialization.XmlReflectionImporter.InitializeStructMembers(StructMapping mapping, StructModel model, Boolean openModel, String typeName, RecursionLimiter limiter)
   --- End of inner exception stack trace ---
   at System.Xml.Serialization.XmlReflectionImporter.InitializeStructMembers(StructMapping mapping, StructModel model, Boolean openModel, String typeName, RecursionLimiter limiter)
   at System.Xml.Serialization.XmlReflectionImporter.ImportStructLikeMapping(StructModel model, String ns, Boolean openModel, XmlAttributes a, RecursionLimiter limiter)
   at System.Xml.Serialization.XmlReflectionImporter.ImportTypeMapping(TypeModel model, String ns, ImportContext context, String dataType, XmlAttributes a, Boolean repeats, Boolean openModel, RecursionLimiter limiter)
   --- End of inner exception stack trace ---
   at System.Xml.Serialization.XmlReflectionImporter.ImportTypeMapping(TypeModel model, String ns, ImportContext context, String dataType, XmlAttributes a, Boolean repeats, Boolean openModel, RecursionLimiter limiter)
   at System.Xml.Serialization.XmlReflectionImporter.ImportAccessorMapping(MemberMapping accessor, FieldModel model, XmlAttributes a, String ns, Type choiceIdentifierType, Boolean rpc, Boolean openModel, RecursionLimiter limiter)
   at System.Xml.Serialization.XmlReflectionImporter.ImportFieldMapping(StructModel parent, FieldModel model, XmlAttributes a, String ns, RecursionLimiter limiter)
   at System.Xml.Serialization.XmlReflectionImporter.InitializeStructMembers(StructMapping mapping, StructModel model, Boolean openModel, String typeName, RecursionLimiter limiter)
   --- End of inner exception stack trace ---
   at System.Xml.Serialization.XmlReflectionImporter.InitializeStructMembers(StructMapping mapping, StructModel model, Boolean openModel, String typeName, RecursionLimiter limiter)
   at System.Xml.Serialization.XmlReflectionImporter.ImportStructLikeMapping(StructModel model, String ns, Boolean openModel, XmlAttributes a, RecursionLimiter limiter)
   at System.Xml.Serialization.XmlReflectionImporter.ImportTypeMapping(TypeModel model, String ns, ImportContext context, String dataType, XmlAttributes a, Boolean repeats, Boolean openModel, RecursionLimiter limiter)
   --- End of inner exception stack trace ---
   at System.Xml.Serialization.XmlReflectionImporter.ImportTypeMapping(TypeModel model, String ns, ImportContext context, String dataType, XmlAttributes a, Boolean repeats, Boolean openModel, RecursionLimiter limiter)
   at System.Xml.Serialization.XmlReflectionImporter.ImportElement(TypeModel model, XmlRootAttribute root, String defaultNamespace, RecursionLimiter limiter)
   at System.Xml.Serialization.XmlReflectionImporter.ImportTypeMapping(Type type, XmlRootAttribute root, String defaultNamespace)
   at System.Xml.Serialization.XmlSerializer..ctor(Type type, String defaultNamespace)
   at System.Xml.Serialization.XmlSerializer..ctor(Type type)
   at Program.main(String[] argv) in C:\Users\eperret\Desktop\SepaConversion\SepaConversion\Program.fs:line 221

Natalie Perret · Accepted Answer

I found out the issue:

List does not work for the serialization of a collection of elements in :

[]
[]
type PaymentInformation = {
    []
    PaymentInformationId: string

    []
    PaymentMethod: string 

    []
    TransactionCount: string

    []
    ControlSum: string

    []
    PaymentTypeInformation: PaymentTypeInformation 

    []
    RequestedExecutionDate: string

    []
    Debtor: Debtor 

    []
    DebtorAccount: DebtorAccount

    []
    DebtorAgent: DebtorAgent 

    []
    ChargeBearer: string 

    []
    CreditTransferTransactionInformation: List  
}

In particular:

[]
CreditTransferTransactionInformation: List

Which needed to be converted to an actual array:

[]
CreditTransferTransactionInformation: CreditTransferTransactionInformation[]

Then it works like a charm!

F# SEPA XML Serialization throws an exception

Answers (1)

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