Nullable value with xsd.exe generated class

问题:

I have been using xsd.exe to generate a class for deserializing XML into. I have decimal value in the source xsd that is not required:

<xs:attribute name="Balance" type="xs:decimal" use="optional" />

The resulting class from xsd generates the following code:

private decimal balanceField;

[System.Xml.Serialization.XmlAttributeAttribute()]
public decimal Balance {
    get {
        return this.balanceField;
    }
    set {
        this.balanceField = value;
    }
}

Which I note is not nullable.

How do I instead generate the field as nullable, illustrated as follows:

private decimal? balanceField;

[System.Xml.Serialization.XmlAttributeAttribute()]
public decimal? Balance {
    get {
        return this.balanceField;
    }
    set {
        this.balanceField = value;
    }
}

回答1:

Currently it works as it should. I'm using xsd v2.0.50727.42 and:

<xs:element name="Port" type="xs:int" nillable="true" />

generates exactly what you've been looking for (without redundant ...Specified field and property):

private System.Nullable<int> portField;

[System.Xml.Serialization.XmlElementAttribute(IsNullable = true)]
public System.Nullable<int> Port {
    get {
        return this.portField;
    }
    set {
        this.portField = value;
    }
}

回答2:

I believe if you add nillable="true" in your XML schema definition, XSD will create a nullable type for that element. This is probably a good idea anyway, since you are implying that this value is indeed nillable and this would make your schema definition more explicit in that regard.

Unfortunately, it still includes the corresponding "Specified" field in this case. If you want the serializer to obey the nullable value directly, you will need to manually remove the "xxSpecified" column from the generated code.

回答3:

I've just noticed that it has actually included the following code:

private bool balanceFieldSpecified;

[System.Xml.Serialization.XmlIgnoreAttribute()]
public bool BalanceSpecified {
    get {
        return this.balanceFieldSpecified;
    }
    set {
        this.balanceFieldSpecified = value;
    }
}

Which provides the functionality I need.

I'll leave the question open for a while in case there is an elegant way to make use of nullable? type instead.