• Status: Solved
  • Priority: Medium
  • Security: Public
  • Views: 2515
  • Last Modified:

XSD how to specify null in enum

For XSD definition, how can null be included as enum for a field defined as string?

Is this correct:     <xs:enumeration value="null"/>

    <xs:element name="status_color" nillable="true">
            <xs:restriction base="xs:string">
                <xs:enumeration value="G"/>
                <xs:enumeration value="R"/>
                <xs:enumeration value="Y"/>
                <xs:enumeration value="null"/>

I'm using xsd.exe /xsd2code.exe and it   turns the code into this: @null

  [System.CodeDom.Compiler.GeneratedCodeAttribute("Xsd2Code", "")]
    [System.Xml.Serialization.XmlTypeAttribute(AnonymousType=true, Namespace="http://pmve.web.boeing.com/action_item_dtl_in")]
    public enum status_color {
  • 4
  • 2
1 Solution
käµfm³d 👽Commented:
Enums in C# are value types--hence they cannot take a value of null. As far as the "@null", "null" is a reserved word in C#. Because of this, the "@" was pre-pended to it. You can use any reserved word as an identifier in C# if you preface it with an "at" symbol.


käµfm³d 👽Commented:
I should have made the examples a bit clearer:

    char @int = 'a';
    string @struct = "hello";
    Point @class = new Point(1, 3);
nicholsfAuthor Commented:
What about xsd and is this valid for defining null:

 <xs:enumeration value="null"/>

I think it is but I'm not a 100%

Note: I realize that  nillable="true" for the element will work. but if you want a list of valid enum values.
Free Tool: SSL Checker

Scans your site and returns information about your SSL implementation and certificate. Helpful for debugging and validating your SSL configuration.

One of a set of tools we are providing to everyone as a way of saying thank you for being a part of the community.

käµfm³d 👽Commented:
I don't have access to my copy of XMLSpy ATM; the best I can offer right now would be to try empty string for nil:
<xs:enumeration value=""/>

Open in new window

käµfm³d 👽Commented:
It seems to me, however, that having a value of nil defeats the purpose of having an enumeration. An enumeration is a way of saying: "This item MUST be one of these values." A value of nil seems counter-intuitive to me.
nicholsfAuthor Commented:
Many thanks for providing the info on the @ in C#.
That was helpful..increased my knowledge of C#.
Question has a verified solution.

Are you are experiencing a similar issue? Get a personalized answer when you ask a related question.

Have a better answer? Share it in a comment.

Join & Write a Comment

Featured Post

The 14th Annual Expert Award Winners

The results are in! Meet the top members of our 2017 Expert Awards. Congratulations to all who qualified!

  • 4
  • 2
Tackle projects and never again get stuck behind a technical roadblock.
Join Now