public static void Stuff()
{
var pipe = SqlContext.Pipe;
var triggerContext = SqlContext.TriggerContext;
if (triggerContext is null)
{
pipe.Send("The method has been called with a null trigger context.");
return;
}
using (var reader = triggerContext.EventData.CreateReader())
{
var document = XDocument.Load(reader);
var actions = (document.FirstNode as XElement)
.Elements("AlterTableActionList")
.First()
.Elements();
// For some reason XName is a class, so this allocates.
XName Name = "Name";
bool hasRolledBack = false;
foreach (var action in actions)
{
var columns = action.Elements("Columns");
const string protectedColumnName = "credits";
if (action.Name.LocalName == "Drop" ||
action.Name.LocalName == "Alter")
{
if (columns
.SelectMany(col => col.Elements(Name))
.Any(name => name.Value.Equals(
protectedColumnName, StringComparison.CurrentCultureIgnoreCase)))
{
pipe.Send($"The column `{protectedColumnName}` cannot be modified.");
if (!hasRolledBack)
{
Rollback();
hasRolledBack = true;
}
}
}
else if (action.Name.LocalName == "Create")
{
var sb = new StringBuilder("Adding: ");
var lb = new ListBuilder(sb, ", ");
var constraints = action.Elements("Constraints");
var names = columns
.Concat(constraints)
.SelectMany(c => c.Elements(Name))
.Select(a => a.Value);
foreach (var name in names)
{
lb.AppendItem(name);
}
// Debug asserting here is a good idea, actually, but whatever.
if (lb.HasAppended)
{
sb.Append(".");
pipe.Send(sb.ToString());
}
}
}
}
}
