public static DefaultConstraintDefinition DefaultConstraint(Identifier column, ScalarExpression expression)
{
var fragment = new DefaultConstraintDefinition();
fragment.Column = column;
fragment.Expression = expression;
return(fragment);
}
public override void ExplicitVisit(DefaultConstraintDefinition node)
{
_buffer.Append("\talter column ");
node.Column.Accept(this);
_buffer.Append(" set default ");
ScalarExpression expression = node.Expression;
while (expression is ParenthesisExpression)
{
expression = ((ParenthesisExpression)expression).Expression;
}
string columnName = node.Column.Value;
PgTableColumn column = _table.Columns[columnName];
if (expression is IntegerLiteral literal)
{
string value = literal.Value;
if (column.DataType == "bool")
{
if (value == "0")
{
value = "(\'f\')";
}
else
{
value = "(\'t\')";
}
_buffer.Append(value);
return;
}
}
else if (expression is FunctionCall call)
{
string functionName = call.FunctionName.Value.ToLower();
switch (functionName)
{
case "getutcdate":
_buffer.Append("(current_timestamp at time zone 'UTC')");
return;
case "getdate":
_buffer.Append("(localtimestamp)");
return;
case "suser_sname":
_buffer.Append("(session_user)");
return;
default:
throw new InvalidOperationException($"unsupported function {functionName}");
}
}
_buffer.Append("(");
expression.Accept(this);
_buffer.Append(")");
}
protected override object InternalVisit(DefaultConstraintDefinition node)
{
Action <Column> applier = (column) =>
{
column.DefaultValue = EvaluateExpression <object>(node.Expression, Database.GlobalEnvironment);
};
return(applier);
}
/// <summary>
/// This visitor looks for default constraints without any identifier (name) and for those explicitly names them.
/// In the cases where the constraint is unnamed, the ConstraintIdentifier field is null.
/// </summary>
public override void ExplicitVisit(DefaultConstraintDefinition node)
{
if (node.ConstraintIdentifier == null)
{
node.ConstraintIdentifier = new Identifier()
{
Value = string.Format("DF_autonamed_{0}", Guid.NewGuid().ToString("N"))
};
}
}
public override void Visit(DefaultConstraintDefinition node) { this.action(node); }
public override void ExplicitVisit(DefaultConstraintDefinition fragment)
{
_fragments.Add(fragment);
}
