Orchard cms adding data-mediapicker-uploadpath to a custom type - tinymce

Question

I have created a custom type in orchard cms, that has a two column lay out
It has 2 header text fileds and 2 content HTML flavour fileds
Heres the migration :
public class MigrationTwoColumnPageType : DataMigrationImpl
{
public int Create()
{
// Define the project type
ContentDefinitionManager.AlterTypeDefinition("TwoColumnPage", cfg => cfg
.WithSetting("Stereotype", "Content")
.CommomPart()
.AutoroutePart()
.WithPart("TitlePart")
.WithPart("MenuPart")
.WithPart("TagsPart")
.WithPart("PublishLaterPart")
.WithPart("TwoColumnPage")
.Creatable()
.Draftable());
return 1;
}
public int UpdateFrom1()
{
// Define project part - having a part with the same name will create fields in the project type
ContentDefinitionManager.AlterPartDefinition("TwoColumnPage", builder => builder
.TextField("Column1Title", Flavour.Large)
.TextField("Column1Text", Flavour.Html)
.TextField("Column2Title", Flavour.Large)
.TextField("Column2Text", Flavour.Html)
.Attachable());
return 2;
}
}
NOTE: TextField is a custom extension method to make things less verbose
When I try and use the media picker to up load an image into one of these content fields I get a folder not found error, - I have traced this back to the media path on the Request querystring not being set
// media directory to save uploaded files into
var mediaPath = Request["uploadpath"];
in ../../Orchard.MediaPicker/Views/admin/Tab_Url.cshtml
Is there some way to set this using filed settings ?
Seems to work fine for any pages I create, but custom types .... how do I set this value ?
UPDATE
Heres the xml meta data for a page...
<!--Exported from Orchard-->
<Orchard>
<Recipe>
<Name>Generated by Orchard.ImportExport</Name>
<Author>admin</Author>
</Recipe>
<Metadata>
<Types>
<Page ContentTypeSettings.Creatable="True" ContentTypeSettings.Draftable="True" TypeIndexing.Included="true" DisplayName="Page">
<NavigationPart />
<CommonPart DateEditorSettings.ShowDateEditor="true" />
<PublishLaterPart />
<TitlePart />
<AutoroutePart AutorouteSettings.AllowCustomPattern="true" AutorouteSettings.AutomaticAdjustmentOnEdit="false" AutorouteSettings.PatternDefinitions="[{Name:'Title', Pattern: '{Content.Slug}', Description: 'my-page'}]" AutorouteSettings.DefaultPatternIndex="0" />
<BodyPart />
<TagsPart />
<LocalizationPart />
</Page>
</Types>
<Parts>
<NavigationPart ContentPartSettings.Attachable="True" />
<CommonPart ContentPartSettings.Attachable="True" />
<PublishLaterPart ContentPartSettings.Attachable="True" />
<TitlePart ContentPartSettings.Attachable="True" />
<AutoroutePart ContentPartSettings.Attachable="True" />
<BodyPart ContentPartSettings.Attachable="True" BodyPartSettings.FlavorDefault="html" />
<TagsPart ContentPartSettings.Attachable="True" />
<LocalizationPart />
</Parts>
</Metadata>
</Orchard>
Here's the XML meta for my custom type, using TestFiledSetting instead of BodyPartSetting
<!--Exported from Orchard-->
<Orchard>
<Recipe>
<Name>Generated by Orchard.ImportExport</Name>
<Author>admin</Author>
</Recipe>
<Metadata>
<Types>
<TwoColumnPage Stereotype="Content" OwnerEditorSettings.ShowOwnerEditor="false" ContentTypeSettings.Creatable="True" ContentTypeSettings.Draftable="True" DisplayName="Two Column Page">
<CommonPart />
<AutoroutePart AutorouteSettings.PatternDefinitions="[{Name:'/Title', Pattern: '/{Content.Slug}', Description: 'my-page'}]" />
<TitlePart />
<MenuPart />
<TagsPart />
<PublishLaterPart />
<TwoColumnPage />
</TwoColumnPage>
</Types>
<Parts>
<CommonPart ContentPartSettings.Attachable="True" />
<AutoroutePart ContentPartSettings.Attachable="True" />
<TitlePart ContentPartSettings.Attachable="True" />
<MenuPart ContentPartSettings.Attachable="True" />
<TagsPart ContentPartSettings.Attachable="True" />
<PublishLaterPart ContentPartSettings.Attachable="True" />
<TwoColumnPage ContentPartSettings.Attachable="True">
<Column1Title.TextField TextFieldSettings.Required="True" TextFieldSettings.Flavor="Large" TextFieldSettings.Hint="" />
<Column1Text.TextField TextFieldSettings.Required="True" TextFieldSettings.Flavor="Html" TextFieldSettings.Hint="" />
<Column2Title.TextField TextFieldSettings.Required="True" TextFieldSettings.Flavor="Large" TextFieldSettings.Hint="" />
<Column2Text.TextField TextFieldSettings.Required="True" TextFieldSettings.Flavor="Html" TextFieldSettings.Hint="" />
</TwoColumnPage>
</Parts>
</Metadata>
</Orchard>
No mention of data-mediapicker-uploadpath in either. I'm still lost!