Re: Dynamic adding childs to a treestore

[Kjell Ahlstedt <kjell ahlstedt bredband net>]

Due to typedefs Gtk::TreeIter = Gtk::TreeNodeChildren::iterator = 
Gtk::TreeModel::iterator and Gtk::TreeRow = 
Gtk::TreeNodeChildren::value_type = Gtk::TreeModel::Row.

The relation between Gtk::TreeIter and the Gtk::TreeRow that it's 
supposed to point to is weird. If 'iter' is a Gtk::TreeModel::iterator, 
then *iter is a reference to iter itself, cast to a 
Gtk::TreeModel::Row&. I think the consequence is that you can't handle 
the iterators returned from sourceTreeStore->append() the way you do. 
'row' in sourceViewer::appendRow() will point to a temporary object 
which is deleted when sourceViewer::appendRow() returns (possibly earlier).

I think you must store Gtk::TreeModel::Row objects instead of pointers. 
That will mean some copying of Gtk::TreeModel::Row, but I don't think 
you should worry too much about that being inefficient. 
Gtk::TreeModel::Row is a fairly small object.
I've marked in your code where I think you should change it.

Kjell

2012-05-09 15:40, Kees Kling skrev:
> Hi
>
> I'm trying to build a Gtk::TreeStore object dynamically which is 
> filled with records from a mysql table
>
>
> code I'm using to build the TreeStore:
>
> +++++
> for ( vector<mysqlpp::Row>::iterator it = result.begin(); it != 
> result.end(); ++it) {
>         const Gtk::TreeModel::Row* runchild = 
> source->appendRow((string)it->at(0),it->at(1),NULL);
const Gtk::TreeModel::Row runchild = 
source->appendRow((string)it->at(0),it->at(1),NULL);
>         // getting unique runtimes of the model
>         query = dbaseConnection->query();
>         query<<"select distinct basetime from modeldata where MID = 
> "<<it->at(1);
>         vector<mysqlpp::Row>runtime;
>         query.storein(runtime);
>         for (vector<mysqlpp::Row>::iterator itr = runtime.begin(); itr 
> != runtime.end(); ++itr) {
>             const Gtk::TreeModel::Row* fcchild = 
> source->appendRow((string)itr->at(0), 0,
>                 runchild );
const Gtk::TreeModel::Row fcchild = 
source->appendRow((string)itr->at(0), 0, &runchild);
or
source->appendRow((string)itr->at(0), 0, &runchild);
>         }
>     }
> +++++
> In this part I'm calling the method appendRow, which is a method of my 
> TreeView object
>
> +++++++++++++++++
> const Gtk::TreeModel::Row* sourceViewer::appendRow(string name, int id,
const Gtk::TreeModel::Row sourceViewer::appendRow(string name, int id,
>         const Gtk::TreeModel::Row* parent ) {
>     const Gtk::TreeModel::Row* row;
const Gtk::TreeModel::Row row;
>     if ( parent == NULL ) {
>         //Creates a new row at the end of the top-level.
>         row  = &(*(sourceTreeStore->append()));
row  = *(sourceTreeStore->append());
>     } else {
>         //Creates a child list
>         row  = &(*(sourceTreeStore->append(parent->children())));
row  = *(sourceTreeStore->append(parent->children()));
>     }
>     row->set_value(sourceColumns.name,name);
>     row->set_value(sourceColumns.id,id);
row.set_value(sourceColumns.name,name);
row.set_value(sourceColumns.id,id);
>     return row;
> }
> ++++++++++++++++++++
>
>
> As long as my third parameter = NULL, thus not creating a child 
> everything is OK, but when adding a child I get a crash and the nect 
> error
>
> gtkmm:ERROR:treeiter.cc:214:const Gtk::TreeNodeChildren& 
> Gtk::TreeRow::children() const: assertion failed: (!is_end_)
>
> What is wrong here?????