Input string was not of the correct format

Question

I'm trying to deserialize and XML file that is validated to an XSD. But the thing is that one of the nodes can be empty from time to time so I came up with this XSD now

<?xml version="1.0" encoding="UTF-8"?>
<xs:schema xmlns:xs="http://www.w3.org/2001/XMLSchema">
<xs:element name="InterfaceLog">
    <xs:complexType>
        <xs:sequence>
            <xs:element name="Log" maxOccurs="unbounded">
                <xs:complexType>
                    <xs:sequence>
                        <xs:element name="InterfaceID" type="xs:string"/>
        This line -->   <xs:element name="PrOrNumber" type="int-or-empty"/>
                        <xs:element name="MESKey" type="xs:string"/>
                        <xs:element name="MsgStatusCode" type="xs:string"/>
                        <xs:element name="MsgClass" type="xs:string"/>
                        <xs:element name="MsgNumber" type="xs:string"/>
                        <xs:element name="MsgDescription" type="xs:string"/>
                    </xs:sequence>
                </xs:complexType>
            </xs:element>
        </xs:sequence>
    </xs:complexType>
</xs:element>

<xs:simpleType name="int-or-empty">
    <xs:union memberTypes="xs:int empty-string" />
</xs:simpleType>

<xs:simpleType name="empty-string">
    <xs:restriction base="xs:string">
        <xs:enumeration value="" />
    </xs:restriction>
</xs:simpleType>
</xs:schema>

The line PrOrNumber can be empty from time to time so I came up with the simpleType int-or-empty. So now when I try to deserialize the XML , it fails when attempting to deserialize the PrOrNumber (returns error input string is not of valid format).

XML that I'm trying to deserialize

<?xml version="1.0" encoding="utf-8" ?>
<ns2:InterfaceLog xmlns:ns2="foo.com/foo">
<Log>
<InterfaceID>InterFace_Id</InterfaceID>
<PrOrNumber/>
<MESKey>Run</MESKey>
<MsgStatusCode>S</MsgStatusCode>
<MsgClass>Class</MsgClass>
<MsgNumber>123</MsgNumber>
<MsgDescription>Description</MsgDescription>
</Log>
</ns2:InterfaceLog>

And the class that I'm trying to deserialize to

    [XmlRoot("InterfaceLog", Namespace = "foo.com/foo")]
[Serializable]
public class InterfaceLog
{
    [XmlElement("Log", Namespace = "")]
    public List<Log> LogCollection { get; set; }
}

[XmlRoot("Log")]
[Serializable]
public class Log
{
    public Log() { }

    [XmlElement("InterfaceID")]
    public string InterfaceID { get; set; }
    [XmlElement("PrOrNumber")]
    public string PrOrNumber { get; set; }
    [XmlElement("MESKey")]
    public string MESKey { get; set; }
    [XmlElement("MsgStatusCode")]
    public string MsgStatusCode { get; set; }
    [XmlElement("MsgClass")]
    public string MsgClass { get; set; }
    [XmlElement("MsgNumber")]
    public string MsgNumber { get; set; }
    [XmlElement("MsgDescription")]
    public string MsgDescription { get; set; }
}

And the function that does the deserialization

 InterfaceLog interfaceLogCollection = xmlString.Deserialize<InterfaceLog>();

    public static T Deserialize<T>(this string serializedObj) where T : class
    {
        XmlSerializer xs = new XmlSerializer(typeof(T));
        T result;

        using (TextReader reader = new StringReader(serializedObj))
            result = xs.Deserialize(reader) as T;

        return result;
    }

What I've tried

• Changing the type to integer , decimal etc..
• Changing the type to string
• Commenting the line works but that is not a solution
• Setting the XSD tag on Nillable

The thing is I can't change the input XML so adding the xsi:nil="true" tag is not an option

Answer 1

I can only get the behaviour you're describing by changing the type of your Log.PrOrNumber property to int or int?, and Kilazur's second link corrects the issue in my reproduction - you're certain you followed through with what it suggested correctly?

In my reproduction case, the serialiser's getting stuck trying to parse an empty string into an integer. To fix, we expose a string property PrOrNumberRaw for the serialiser to talk to that contains the required parsing logic, and our own property PrOrNumber with the parse value (or null) for the application to consume.

The Log class definition changes to become:

[XmlRoot("Log")]
[Serializable]
public class Log
{
    public Log() { }

    [XmlElement("InterfaceID")]
    public string InterfaceID { get; set; }
    [XmlElement("MESKey")]
    public string MESKey { get; set; }
    [XmlElement("MsgStatusCode")]
    public string MsgStatusCode { get; set; }
    [XmlElement("MsgClass")]
    public string MsgClass { get; set; }
    [XmlElement("MsgNumber")]
    public string MsgNumber { get; set; }
    [XmlElement("MsgDescription")]
    public string MsgDescription { get; set; }

    [XmlElement("PrOrNumber")]
    public string PrOrNumberRaw
    {
        get { return this.PrOrNumber.ToString(); }
        set
        {
            if (!string.IsNullOrWhiteSpace(value))
            {
                this.PrOrNumber = int.Parse(value);
            }
            else
            {
                this.PrOrNumber = null;
            }
        }
    }

    [XmlIgnore]
    public int? PrOrNumber { get; set; }
}