public override void Perform(SchemaChanges changes, IOutput output)
{
if (changes.Options.FieldDropBehavior == DropBehavior.SkipDrop)
{
return;
}
var errorResponse = changes.Options.FieldDropBehavior == DropBehavior.TryDrop ? ErrorResponse.Ignore : ErrorResponse.Fail;
foreach (var current in FieldType.AllFrom(changes.Current))
{
if (changes.Desired.Contains(current))
{
continue;
}
// If we're going to drop the whole table then don't bother dropping the field
if (!changes.Desired.ContainsRoot(current.ParentIdentifier))
{
continue;
}
if (!changes.AllowDropWithPossibleDataLoss(current, changes.Options.FieldDropBehavior))
{
continue;
}
changes.Remove(changes.SchemaDriver.GetDropFieldSql(current.ParentName, current.Name), current);
}
}
public override void Perform(SchemaChanges changes, IOutput output)
{
foreach (var current in FieldType.AllFrom(changes.Current))
{
var desired = FieldType.GetDesired(changes, current);
// At this point we are only dropping changed fields, not fields that are being
// removed entirely, which we keep around til later to allow them to be used by
// before statements for migration. So we only want to drop fields that conflict
// with fields in the eventual state of the table (including the conflict
// that would occur if two identity fields existed in the same table).
if (desired == null && !isSequencedPkeyToBeDropped(changes, current))
{
continue;
}
// If the type and sequenced-ness are unchanged then we don't need to do anything here.
if (desired != null && FieldType.IsTypeEqual(current.State, desired.State, changes.SchemaDriver.IsSequencedPartOfFieldDeclaration))
{
continue;
}
// Fields being dropped here need to be replaced later, so failing to drop them has to be fatal regardless of FieldDropBehavior
if (!changes.AllowDropWithPossibleDataLoss(current, DropBehavior.Drop))
{
continue;
}
// If we are about to drop the last field from a table, add a temporary field so that the drop will be allowed
if (FieldType.ChildrenFrom(changes.Current, current.ParentIdentifier).Count() == 1)
{
var placeholder = FieldType.Create(current.ParentIdentifier, "nrdo_placeholder_field", 2, "int", true);
changes.Put(changes.SchemaDriver.GetAddFieldSql(placeholder.ParentName, placeholder.Name, placeholder.State.DataType, false, null), placeholder);
if (changes.HasFailed)
{
continue;
}
}
// Drop the field
changes.Remove(changes.SchemaDriver.GetDropFieldSql(current.ParentName, current.Name), current);
}
}
public override void Perform(SchemaChanges changes, IOutput output)
{
if (changes.Options.TableDropBehavior == DropBehavior.SkipDrop)
{
return;
}
var errorResponse = changes.Options.TableDropBehavior == DropBehavior.TryDrop ? ErrorResponse.Ignore : ErrorResponse.Fail;
foreach (var current in TableType.AllFrom(changes.Current))
{
if (changes.Desired.Contains(current))
{
continue;
}
if (!changes.AllowDropWithPossibleDataLoss(current, changes.Options.TableDropBehavior))
{
continue;
}
// Drop the table
changes.Remove(changes.SchemaDriver.GetDropTableSql(current.Name), errorResponse, current);
}
}
