/// <summary>
/// Creates a record for an extent containing default values. Assumes the extent is either
/// a relationship set or an entity set.
/// </summary>
/// <remarks>
/// Each scalar value appearing in the record is a <see cref="DbConstantExpression" />. A placeholder is created by recursively
/// building a record, so an entity record type will return a new record (<see cref="DbNewInstanceExpression" />)
/// consisting of some recursively built record for each column in the type.
/// </remarks>
/// <param name="extent"> Extent </param>
/// <returns> A default record for the </returns>
internal static PropagatorResult CreatePlaceholder(EntitySetBase extent)
{
DebugCheck.NotNull(extent);
var creator = new ExtentPlaceholderCreator();
var associationSet = extent as AssociationSet;
if (null != associationSet)
{
return creator.CreateAssociationSetPlaceholder(associationSet);
}
var entitySet = extent as EntitySet;
if (null != entitySet)
{
return creator.CreateEntitySetPlaceholder(entitySet);
}
throw new NotSupportedException(
Strings.Update_UnsupportedExtentType(
extent.Name, extent.GetType().Name));
}
