private static Expression GetExpression <T>(ParameterExpression param, FilterObject filter)
{
MemberExpression member = Expression.Property(param, filter.Column);
//ConstantExpression constant = Expression.Constant(filter.Value);
// NEW LOGIC to handle nullable Decimal and DateTime values
UnaryExpression constant = null;
if (member.Type == typeof(Decimal?))
{
constant = Expression.Convert(Expression.Constant(Decimal.Parse(filter.Value)), member.Type);
}
else if (member.Type == typeof(DateTime?))
{
constant = Expression.Convert(Expression.Constant(DateTime.Parse(filter.Value)), member.Type);
}
else
{
constant = Expression.Convert(Expression.Constant(filter.Value), member.Type);
}
switch (filter.Operator)
{
case FilterOperator.Equals:
return(Expression.Equal(member, constant));
case FilterOperator.GreaterThan:
return(Expression.GreaterThan(member, constant));
case FilterOperator.GreaterThanOrEqual:
return(Expression.GreaterThanOrEqual(member, constant));
case FilterOperator.LessThan:
return(Expression.LessThan(member, constant));
case FilterOperator.LessThanOrEqual:
return(Expression.LessThanOrEqual(member, constant));
case FilterOperator.Contains:
return(Expression.Call(member, containsMethod, constant));
case FilterOperator.StartsWith:
return(Expression.Call(member, startsWithMethod, constant));
case FilterOperator.EndsWith:
return(Expression.Call(member, endsWithMethod, constant));
case FilterOperator.NotEqual:
return(Expression.Negate(Expression.Equal(member, constant)));
}
return(null);
}
private static BinaryExpression GetExpression <T> (ParameterExpression param, FilterObject filter1, FilterObject filter2)
{
Expression bin1 = GetExpression <T>(param, filter1);
Expression bin2 = GetExpression <T>(param, filter2);
return(Expression.AndAlso(bin1, bin2));
}
public static string GetWhereClause(FilterObject filterObj, Type valueType)
{
string whereClause = "true";
if (valueType != typeof(DateTime))
{
switch (filterObj.Operator)
{
case FilterOperator.Contains:
if (valueType == typeof(string))
{
whereClause += string.Format(" {0} {1}.Contains(\"{2}\")", filterObj.Conjunction,
filterObj.Column, filterObj.Value);
}
break;
case FilterOperator.GreaterThan:
if (valueType != typeof(string))
{
whereClause += string.Format(" {0} {1} > {2}", filterObj.Conjunction, filterObj.Column,
filterObj.Value);
}
break;
case FilterOperator.GreaterThanOrEqual:
if (valueType != typeof(string))
{
whereClause += string.Format(" {0} {1} >= {2}", filterObj.Conjunction, filterObj.Column,
filterObj.Value);
}
break;
case FilterOperator.LessThan:
if (valueType != typeof(string))
{
whereClause += string.Format(" {0} {1} < {2}", filterObj.Conjunction, filterObj.Column,
filterObj.Value);
}
break;
case FilterOperator.LessThanOrEqual:
if (valueType != typeof(string))
{
whereClause += string.Format(" {0} {1} <= {2}", filterObj.Conjunction, filterObj.Column,
filterObj.Value);
}
break;
case FilterOperator.StartsWith:
if (valueType != typeof(string))
{
whereClause += string.Format(" {0} {1}.StartsWith(\"{2}\")", filterObj.Conjunction,
filterObj.Column, filterObj.Value);
}
break;
case FilterOperator.EndsWith:
if (valueType != typeof(string))
{
whereClause += string.Format(" {0} {1}.EndsWith(\"{2}\")", filterObj.Conjunction,
filterObj.Column, filterObj.Value);
}
break;
case FilterOperator.Equals:
whereClause +=
string.Format(valueType == typeof(string) ? " {0} {1} == \"{2}\"" : " {0} {1} == {2}",
filterObj.Conjunction, filterObj.Column, filterObj.Value);
break;
case FilterOperator.NotEqual:
whereClause +=
string.Format(valueType == typeof(string) ? " {0} {1} != \"{2}\"" : " {0} {1} != {2}",
filterObj.Conjunction, filterObj.Column, filterObj.Value);
break;
default:
throw new ArgumentOutOfRangeException();
}
}
else
{
DateTime dt;
DateTime.TryParse(filterObj.Value, out dt);
switch (filterObj.Operator)
{
case FilterOperator.Contains:
break;
case FilterOperator.GreaterThan:
whereClause += string.Format(" {0} {1} > DateTime(\"{2}\")", filterObj.Conjunction, filterObj.Column, dt);
break;
case FilterOperator.GreaterThanOrEqual:
whereClause += string.Format(" {0} {1} >= DateTime(\"{2}\")", filterObj.Conjunction, filterObj.Column, dt);
break;
case FilterOperator.LessThan:
whereClause += string.Format(" {0} {1} < DateTime(\"{2}\")", filterObj.Conjunction, filterObj.Column, dt);
break;
case FilterOperator.LessThanOrEqual:
whereClause += string.Format(" {0} {1} <= DateTime(\"{2}\")", filterObj.Conjunction, filterObj.Column, dt);
break;
case FilterOperator.StartsWith:
break;
case FilterOperator.EndsWith:
break;
case FilterOperator.Equals:
whereClause += string.Format(" {0} {1} == DateTime(\"{2}\")", filterObj.Conjunction, filterObj.Column, dt);
break;
case FilterOperator.NotEqual:
whereClause += string.Format(" {0} {1} != DateTime(\"{2}\")", filterObj.Conjunction, filterObj.Column, dt);
break;
default:
throw new ArgumentOutOfRangeException();
}
}
return(whereClause);
}