displaying custom data types in a table Wt::WTableView
Added by Anton Erykalin about 1 year ago
Hello.
Help please.
I have defined my class based on std::string class.
class IpString : public std::string
{
using base = std::string;
public:
using base::base;
static std::vector<int> ipV4StringToInt(IpString ipString);
friend bool operator< (const IpString &left, const IpString &right)
{
std::vector<int> lToInt = IpString::ipV4StringToInt(left);
std::vector<int> rToInt = IpString::ipV4StringToInt(right);
return (lToInt[0]<=rToInt[0]) && (lToInt[1]<=rToInt[1]) && (lToInt[2]<=rToInt[2]) && (lToInt[3]<rToInt[3]);
}
friend bool operator> (const IpString &left, const IpString &right)
{
std::vector<int> lToInt = IpString::ipV4StringToInt(left);
std::vector<int> rToInt = IpString::ipV4StringToInt(right);
return (lToInt[0]>=rToInt[0]) && (lToInt[1]>=rToInt[1]) && (lToInt[2]>=rToInt[2]) && (lToInt[3]>rToInt[3]);
}
friend bool operator<= (const IpString &left, const IpString &right)
{
std::vector<int> lToInt = IpString::ipV4StringToInt(left);
std::vector<int> rToInt = IpString::ipV4StringToInt(right);
return (lToInt[0]<=rToInt[0]) && (lToInt[1]<=rToInt[1]) && (lToInt[2]<=rToInt[2]) && (lToInt[3]<=rToInt[3]);
}
friend bool operator>= (const IpString &left, const IpString &right)
{
std::vector<int> lToInt = IpString::ipV4StringToInt(left);
std::vector<int> rToInt = IpString::ipV4StringToInt(right);
return (lToInt[0]>=rToInt[0]) && (lToInt[1]>=rToInt[1]) && (lToInt[2]>=rToInt[2]) && (lToInt[3]>=rToInt[3]);
}
};
I am giving a dataset of objects of this class to a table, but nothing is showing up in the table. That is, I get just empty fields equal to the number of front rows for the table. Perhaps I forgot to override / define some method in my class that is needed to display in the table. And is it possible to give Wt::WTableView custom data types?
Replies (3)
RE: displaying custom data types in a table Wt::WTableView - Added by Anton Erykalin about 1 year ago
Here is an example for a better understanding of what is happening to me, for the elements of the first column I passed my class IpString
RE: displaying custom data types in a table Wt::WTableView - Added by Roel Standaert about 1 year ago
You'll have to make sure any_traits is properly implemented for your type, and register it.
Wt::asString(...) is only implemented by default for exactly std::string, not derived classes of it.
Deriving from any STL classes, like std::string, is a bad idea, too. std::string does not have a virtual destructor, so you can get undefined behavior by destroying it through a std::string* (see Item 7 from Effective C++). Also, your IpString type appears to me to add an invariant to std::string, but there's all sorts of functions, like operator+=, that you could call on it and invalidate this invariant.
RE: displaying custom data types in a table Wt::WTableView - Added by Anton Erykalin about 1 year ago
Yes, you are absolutely right, I completely forgot about the absence of a virtual destructor. I'm just trying to fix the sorting of the IP strings. I believe that I have only two options left, to make a class based on a Wt::WString or somehow give my own sorting rule.
Problem I'm trying to solve is the correct sorting of strings with IP addresses. now if I sort for example in ascending order, then I will get something like this:
- 192.168.1.11
- 192.168.1.20
- 192.168.1.3
That is, the sorting occurred character-by-character as for simple strings.
And this behavior does not suit me. I would like the rows to be sorted like this:
- 192.168.1.3
- 192.168.1.11
- 192.168.1.20