title: How do I override the get; set; properties of a field?
body: <p>I'm working with a database that due to reason out of my control - I cannot modify the schema.</p>
  
  <p>This database has a field "CertificateId" that is non-nullable, however, the field is still considered to be optional. When I load this field into my model (I'm using the DB first approach), it is of course tagged as being non-nullable, as you can see in the designer.cs</p>
  
  <pre><code>[EdmScalarPropertyAttribute(EntityKeyProperty = false, IsNullable = false)]
  [DataMemberAttribute()]
  public global::System.String CertificateId
  {
      get
      {
          return _CertificateId;
      }
      set
      {
          OnCertificateIdChanging(value);
          ReportPropertyChanging("CertificateId");
          _CertificateId = StructuralObject.SetValidValue(value, false);
          ReportPropertyChanged("CertificateId");
          OnCertificateIdChanged();
      }
  }
  </code></pre>
  
  <p>Since this field is optional, it gets passed null sometimes, which obviously fails validation.</p>
  
  <p>Is there any way of overloading these properties that are autogenerated? I would like to be able to check if the value passed into the set property is null, and if it is, set it to an empty string before it goes into validation.</p>
  
  <p>Or, is it possible to override the metadata for this property and have IsNullable set to true?</p>