Issue updating a custom field type

Question

I've created a custom field type called CompanyRule.

I've created a content type call RulesCT with four site columns that are of type CompanyRule. Initially I can give and update the values of the the custom parameters without any problem.

I created a list that used the RulesCT content type. Now when I update the custom parameters while "Update all list columns based on this site column?" is set to yes, it blanks out all of the custom parameters. If I set it to no, it works as expected. Below are two functions that seem to be where the error occurs but I can't tell what it might be. Any help would be appreciated.

    //Field is updated
    public override void OnUpdated()
    {
        SPAddFieldOptions op = SPAddFieldOptions.Default;

        String addFieldOptionPropertyValue = this.GetProperty("AddFieldOption");
        if (!String.IsNullOrEmpty(addFieldOptionPropertyValue))
        {
            op = (SPAddFieldOptions)Enum.Parse(typeof(SPAddFieldOptions), this.GetProperty("AddFieldOption"), true);
        }
        if (!this.savingSchemaXml)
        {
            this.savingSchemaXml = true;
            base.SchemaXml = this.CreateOrUpdateFieldSchemaXml(op);
            this.CleanThreadLocalStorage();
        }
    }

    //
    private string CreateOrUpdateFieldSchemaXml(SPAddFieldOptions op)
    {
        XElement schemaXmlElement = XElement.Parse(this.SchemaXml);
        schemaXmlElement.SetAttributeValue("CFDCTMID", this.GetPropertyFromThread<string>("CFDCTMID"));
        schemaXmlElement.SetAttributeValue("CFStatus", this.GetPropertyFromThread<string>("CFStatus"));
        schemaXmlElement.SetAttributeValue("CFType", this.GetPropertyFromThread<string>("CFType"));
        schemaXmlElement.SetAttributeValue("CFDefaultValue", this.GetPropertyFromThread<string>("CFDefaultValue"));
        schemaXmlElement.SetAttributeValue("CFDataSource", this.GetPropertyFromThread<string>("CFDataSource"));
        schemaXmlElement.SetAttributeValue("CFDataTable", this.GetPropertyFromThread<string>("CFDataTable"));
        schemaXmlElement.SetAttributeValue("CFLabCol", this.GetPropertyFromThread<string>("CFLabCol"));
        schemaXmlElement.SetAttributeValue("CFValCol", this.GetPropertyFromThread<string>("CFValCol"));
        schemaXmlElement.SetAttributeValue("CFParentControl", this.GetPropertyFromThread<string>("CFParentControl"));
        schemaXmlElement.SetAttributeValue("CFParentChangeQuery", this.GetPropertyFromThread<string>("CFParentChangeQuery"));
        schemaXmlElement.SetAttributeValue("CFChildControl", this.GetPropertyFromThread<string>("CFChildControl"));
        schemaXmlElement.SetAttributeValue("CFChildChangeQuery", this.GetPropertyFromThread<string>("CFChildChangeQuery"));
        schemaXmlElement.SetAttributeValue("CFEventTriggerGroup", this.GetPropertyFromThread<string>("CFEventTriggerGroup"));
        schemaXmlElement.SetAttributeValue("CFEventListenerGroup", this.GetPropertyFromThread<string>("CFEventListenerGroup"));
        schemaXmlElement.SetAttributeValue("CFEventListenerAction", this.GetPropertyFromThread<string>("CFEventListenerAction"));
        schemaXmlElement.SetAttributeValue("CFSearchOrder", this.GetPropertyFromThread<string>("CFSearchOrder"));
        schemaXmlElement.SetAttributeValue("CFUploadOrder", this.GetPropertyFromThread<string>("CFUploadOrder"));

        //TRY / CATCH in place because you can not unbox a generic of type bool when it is null - apparently
        try
        { schemaXmlElement.SetAttributeValue("CFSearchVisible", this.GetPropertyFromThread<bool>("CFSearchVisible")); }
        catch
        { schemaXmlElement.SetAttributeValue("CFSearchVisible", this.GetPropertyFromThread<string>("CFSearchVisible")); }
        try
        { schemaXmlElement.SetAttributeValue("CFUploadVisible", this.GetPropertyFromThread<bool>("CFUploadVisible")); }
        catch
        { schemaXmlElement.SetAttributeValue("CFUploadVisible", this.GetPropertyFromThread<string>("CFUploadVisible")); }

        schemaXmlElement.SetAttributeValue("AddFieldOption", op.ToString());
        return (schemaXmlElement.ToString());
    }

Answer 1

I've resolved the problem. I don't think I can fully articulate the solution but I'll do my best.

There were three scenarios that I tested. These all used a site column that was of the custom field type.

1. I created updated the site column in the site settings section.
2. I created a content type that used the site column. I updated the site column and set "Update all list columns based on this site column?" to No.
3. I created a content type that used the site column. I updated the site column and set "Update all list columns based on this site column?" to Yes.

I was able to update the custom properties for option 1 and 2 but when I did it for option 3 it blanked out all the values.

After crawling through the code I found that options 1 and 2 take a different path to 3. The solution was to update the code for each field in the CreateOrUpdateFieldSchemaXml method that I posted above to:

change:

        schemaXmlElement.SetAttributeValue("CFDCTMID", this.GetPropertyFromThread<string>("CFDCTMID"));

to:

        if (String.IsNullOrEmpty("CFDCTMID"))
        {
            schemaXmlElement.SetAttributeValue("CFDCTMID", this.GetPropertyFromThread<TProperty>("CFDCTMID"));
        }
        else
        {
            schemaXmlElement.SetAttributeValue("CFDCTMID", CFDCTMID);
        }