public static ExpressionType ToExpressionType(this FilterOps operand)
{
switch (operand)
{
case FilterOps.GreaterThan: return(ExpressionType.GreaterThan);
case FilterOps.LessThan: return(ExpressionType.LessThan);
case FilterOps.Equal: return(ExpressionType.Equal);
default: throw new NotSupportedException();
}
}
private string getWhere()
{
StringBuilder sb = new StringBuilder();
//if (_queryParams != null && _queryParams.Count > 0 && _isSourceTable)
//{
// foreach (string key in _queryParams.Keys)
// {
// sb.Append(" and ");
// sb.Append(key);
// sb.Append("=");
// sb.Append(_queryParams[key]);
// }
//}
if (_filterRules != null && _filterRules.Count > 0)
{
foreach (FilterRule fr in _filterRules)
{
if (string.IsNullOrEmpty(fr.op))
{
continue;
}
FilterOps op = FilterOpSigns.parse(fr.op);
if (op == FilterOps.nofilter)
{
continue;
}
sb.Append(" and ");
sb.Append(fr.field);
sb.Append(FilterOpSigns.getSign(op));
switch (op)
{
case FilterOps.isnull:
case FilterOps.notnull:
continue;
}
sb.Append(" '");
switch (op)
{
case FilterOps.contains:
case FilterOps.endwith:
sb.Append("%");
break;
}
sb.Append(fr.value);
switch (op)
{
case FilterOps.contains:
case FilterOps.beginwith:
sb.Append("%");
break;
}
sb.Append("' ");
}
}
if (sb.Length > 0)
{
sb.Remove(0, " and ".Length);
}
return(sb.ToString());
}
public static string getSign(string op)
{
FilterOps fop = parse(op);
return(getSign(fop));
}
public Expression <Predicate <T> > GetFilterPredicate <T, R>(Expression <Func <T, R> > selector, FilterOps operand, R value)
{
var parameter = selector.Parameters[0];
var left = selector.Body;
var right = Expression.Constant(value);
var binaryExpression = Expression.MakeBinary(operand.ToExpressionType(), left, right);
return(Expression.Lambda <Predicate <T> >(binaryExpression, parameter));
}
public static string getSign(FilterOps op)
{
return(_signs[op]);
}