private static Expression <Func <T, bool> > GetExpressionFromConditon <T> (string condition, IQueryObject queryObj, QueryColumnMapper <T> columnMapper)
{
try {
string[] op = { "==", "!=", "=*", "!*", ">>", "<<", ">=", "<=" };
var maps = queryObj.ParseFilter(condition, op);
if (!maps.HasValue)
{
return(null);
}
Expression <Func <T, object> > exp = columnMapper.Mappings[maps.Value.Left];
var body = exp.Body;
// Remove the boxing for value types
if (body.NodeType == ExpressionType.Convert)
{
body = ((UnaryExpression)body).Operand;
}
object value = maps.Value.Right;
if (value != null && body.Type != value.GetType())
{
var converter = TypeDescriptor.GetConverter(body.Type);
value = converter.ConvertFromString(value.ToString());
// value = Convert.ChangeType(value, body.Type);
}
Expression be = null;
var ContainsMethod = typeof(string).GetMethod("Contains", new [] { typeof(string) });
switch (maps.Value.Operation)
{
case "==":
be = Expression.Equal(body, Expression.Constant(value, body.Type));
break;
case "!=":
be = Expression.NotEqual(body, Expression.Constant(value, body.Type));
break;
case ">>":
be = Expression.GreaterThan(body, Expression.Constant(value, body.Type));
break;
case "<<":
be = Expression.LessThan(body, Expression.Constant(value, body.Type));
break;
case ">=":
be = Expression.GreaterThanOrEqual(body, Expression.Constant(value, body.Type));
break;
case "<=":
be = Expression.LessThanOrEqual(body, Expression.Constant(value, body.Type));
break;
case "=*":
be = Expression.Call(body, ContainsMethod, Expression.Constant(value, body.Type));
break;
case "!*":
be = Expression.Not(Expression.Call(body, ContainsMethod, Expression.Constant(value, body.Type)));
break;
default:
return(null);
}
return(Expression.Lambda <Func <T, bool> > (be, exp.Parameters));
} catch (Exception) {
return(null);
}
}
private static Expression <Func <T, bool> > GetExpressionFromInternalConditions <T> (IQueryObject queryObj, QueryColumnMapper <T> columnMapper, List <(string condition, bool IsAnd)> conditions)