default value as null for a bool type in a profile provider

Question

I have a custom profile defined in my webconfig. I have this property defined

<add name="sex" type="bool" serializeAs="String" defaultValue="[null]"/>

as there are null values in the database. I get a null reference exception in this code:

    ProfileCommon p = GetProfile();
            txtFirstName.Text = p.first_name;
            txtLastName.Text = p.last_name;
            txtInitial.Text = p.initial;
            txtEmail.Text = p.email;

//this causes an null reference exception bool? blnTest = p.sex;

Is this the correct way to set a default null value in webconfig?

Answer 1

The problem here is that the default type of a profile property is bool which is not a nullable type. It will always default to false.

You could always create a custom class to encapsulate Sex / Gender and use this instead of bool. That way when there is no value set the class will then attempt to instantiate and revert to null as required.

Changes to web config:

 <profile defaultProvider="MyProfileProvider" inherits="FTS.Membership.Profile.MyProfileProvider,FTS.Membership">
      <providers>
        <clear/>
        <add name="MyProfileProvider" connectionStringName="LocalSqlServer" applicationName="/" type="FTS.Membership.Profile.MyProfileProvider,FTS.Membership"/>
      </providers>
      <properties>
        <add name="first_name" type="string" serializeAs="String" defaultValue=""/>
        <add name="last_name" type="string" serializeAs="String" defaultValue=""/>
        <add name="initial" type="string" serializeAs="String" defaultValue=""/>
        <add name="email" type="string" serializeAs="String"/>
        <add name="active" type="bool" serializeAs="String" defaultValue="false"/>
        <add name="creation_date" type="datetime" serializeAs="String"/>
        <add name="update_date" type="datetime" serializeAs="String"/>
        <add name="last_activity_date" type="datetime" serializeAs="String"/>
        <!--<add name="sex" type="bool" serializeAs="String" defaultValue="false"/>-->

      </properties>
    </profile>

and the class:

using System;
using System.Web.Profile;
using System.Collections.Generic;

namespace FTS.Membership.Profile
{
    public class MyProfileProvider : ProfileBase
    {
        public bool? sex
        {
            get {
                if (base["sex"] == null)
                {
                    return null;
                }
                return (bool)base["sex"];
            }
            set { base["sex"] = value; }
        }
    }
}