Gtkmm3 TreeView ListStore.Clear或TreeSelection.unselectAll导致错误

Question

我试图使用TreeView列出目录的内容，然后在列表中选择文件名。我不想使用文件选择器对话框，因为我想限制用户对一个目录的访问，不希望他们在系统中导航。我的代码可以正常工作，直到我想清除列表并更新它。如果我访问了一行并读取了列值，那么当我清除列表或使用树选择unSelectAll()时，就会得到以下错误：

gtk_list_store_get_value:断言'iter_is_valid (iter，list_store)‘失败

和

g_value_get_string:断言'G_VALUE_HOLDS_STRING (值)‘失败

代码仍然有效，但我不喜欢这些错误。感觉好像我看错了这一行，但我看不出是怎么回事。请参阅我的代码:最底层的fileForm::on_treeview_selected() 。变量"f“最初是”文件名“，但我对其进行了更改，以证明即使是应该丢弃的变量也会导致iter出现问题。该表单是在Glade中构建的，并使用GTK::Builder引用。我使用的是Linux 18.2‘/*

/* 
 * File:   fileForm.h
 * Author: john
 *
 * Created on November 16, 2017, 6:26 PM
 */

#ifndef FILEFORM_H
#define FILEFORM_H

#include <gtkmm/builder.h>
#include <gtkmm/treeview.h>
#include <gtkmm/liststore.h>
#include <gtkmm/scrolledwindow.h>
#include <gtkmm/scrollbar.h>
#include <gtkmm/cellrendererprogress.h>
#include <gtkmm/button.h>
#include <gtkmm/buttonbox.h>
#include <gtkmm/box.h>
#include <gtkmm/label.h>
#include <gtkmm/entry.h>
#include <gtkmm/window.h>
#include <gtkmm/scrolledwindow.h>
#include <sstream>
#include <dirent.h>
#include <string>
#include "generalClasses.h"


//not using Glade as can't do List Store so pointless

class fileForm   : public Gtk::Window {
public:
    fileForm(BaseObjectType* cobject, const Glib::RefPtr<Gtk::Builder>& refGlade);
    fileForm(const fileForm& orig);
    virtual ~fileForm();
    void show(std::string fileExtension = ""); 
    std::string filename = "";
protected:
    Glib::RefPtr<Gtk::Builder> m_builder;    
    std::string m_fileExtension;

    //Tree model columns:
    class ModelColumns : public Gtk::TreeModel::ColumnRecord
    {
    public:

      ModelColumns()
      { add(m_col_id); add(m_col_name); add(m_col_date);}

      Gtk::TreeModelColumn<unsigned int> m_col_id;
      Gtk::TreeModelColumn<Glib::ustring> m_col_name;
      Gtk::TreeModelColumn<Glib::ustring> m_col_date;
    };

    ModelColumns m_columns;

    //Child widgets:
    Gtk::Button* m_topButton;
    Gtk::Button* m_upButton;
    Gtk::Button* m_downButton;
    Gtk::Button* m_bottomButton;

    Gtk::TreeView* m_treeView;
    Gtk::ScrolledWindow* m_scrolledWindow;
    Glib::RefPtr<Gtk::TreeSelection> m_treeSelection;
    Glib::RefPtr<Gtk::ListStore> m_refTreeModel;
//    Gtk::ListStore* m_refTreeModel;

    Gtk::Button* m_cancelButton;
    Gtk::Button* m_loadButton;
private:
    //Signal handlers:
    void on_loadButton_clicked();
    void on_cancelButton_clicked();
    void on_topButton_clicked();
    void on_upButton_clicked();
    void on_downButton_clicked();
    void on_bottomButton_clicked();
    void on_treeview_selected();

};

#endif /* FILEFORM_H */


/* 
 * File:   fileForm.cpp
 * Author: john
 * 
 * Created on November 16, 2017, 6:26 PM
 */

#include "fileForm.h"

using namespace Glib;
using namespace std;


fileForm::fileForm(BaseObjectType* cobject, const Glib::RefPtr<Gtk::Builder>& refGlade)
: Gtk::Window(cobject),
  m_builder(refGlade)
{
    set_title("Select file");

   m_builder->get_widget("topButton",m_topButton);
   m_builder->get_widget("upButton",m_upButton);
   m_builder->get_widget("downButton",m_downButton);
   m_builder->get_widget("bottomButton",m_bottomButton);

   m_builder->get_widget("cancelButton",m_cancelButton);
   m_builder->get_widget("loadButton",m_loadButton);

   m_builder->get_widget("treeview1",m_treeView);
   m_builder->get_widget("scrolledwindow1", m_scrolledWindow);

   m_refTreeModel = Gtk::ListStore::create(m_columns);
   m_treeView->set_model(m_refTreeModel);
   m_treeSelection = m_treeView->get_selection();
   //Add the TreeView's view columns:
   //This number will be shown with the default numeric formatting.
   m_treeView->append_column("ID", m_columns.m_col_id);
   m_treeView->append_column("Name", m_columns.m_col_name);
   m_treeView->append_column("Date",m_columns.m_col_date);



    m_cancelButton->signal_clicked().connect(sigc::mem_fun(*this, &fileForm::on_cancelButton_clicked));
    m_loadButton->signal_clicked().connect(sigc::mem_fun(*this, &fileForm::on_loadButton_clicked));
   m_treeSelection->signal_changed().connect(sigc::mem_fun(*this, &fileForm::on_treeview_selected),false); 
}

void fileForm::show(std::string fileExtension){

    //open file and list
    int rowCount = 0;
    char buffer[30];
    DIR *d;
    struct dirent *dir;
    struct stat fileAttrib;
    string s;
    int pointPos;

    filename = "";
    m_treeSelection->unselect_all();    //fault occurs on this line if the row.get_value was used
    m_refTreeModel->clear();  //fault occurs on this line if the row.get_value was used

    d = opendir(".");
    if (d)
    {
        while ((dir = readdir(d)) != NULL)
        {
          stat(dir->d_name, &fileAttrib);  
            s = dir->d_name;
            pointPos = s.find("." + fileExtension);
            s = s.substr(0,pointPos);        
          //Fill the TreeView's model
          if ((s !=".") && (s !="..") && (s != "") && (pointPos > 0))   //show only files and no directories
          {
            Gtk::TreeModel::Row row = *(m_refTreeModel->append());
            row[m_columns.m_col_id] = ++rowCount;
            row[m_columns.m_col_name] = s;
            timespecToStr(buffer, &fileAttrib.st_mtim);
            if (buffer != NULL)
                row[m_columns.m_col_date] = buffer;
          }

        }
    }  



  if (rowCount < 12)        //nasty but itll do for now
  {
    m_treeView->set_size_request(400,-1);
    m_topButton->set_sensitive(false);
    m_upButton->set_sensitive(false);
    m_downButton->set_sensitive(false);
    m_bottomButton->set_sensitive(false);
  }
  else    
  {
    m_treeView->set_size_request(400,400);
    m_topButton->set_sensitive(true);
    m_upButton->set_sensitive(true);
    m_downButton->set_sensitive(true);
    m_bottomButton->set_sensitive(true);
  }


    //Make all the columns reorderable:
  //This is not necessary, but it's nice to show the feature.
  //You can use TreeView::set_column_drag_function() to more
  //finely control column drag and drop.
  /*
  for(guint i = 0; i < 3; i++)
  {
    auto column = m_treeView->get_column(i);
    column->set_reorderable();
  }
  */
  m_loadButton->set_sensitive(false);   //disabled until a selection is made
  m_cancelButton->grab_focus();

    Gtk::Window::show_all();  
}


void fileForm::on_loadButton_clicked()
{
  //filename selected when tree selected
  filename += "." + m_fileExtension;  
  hide();
}

void fileForm::on_cancelButton_clicked()
{
  filename = "";
  hide();
}

void fileForm::on_treeview_selected()
{
  ustring f = "";  
  m_loadButton->set_sensitive(true);   //disabled until a selection is made

  Gtk::TreeIter treeiter = m_treeSelection->get_selected();
  Gtk::TreeModel::Row row = *treeiter;
  f = row.get_value(m_columns.m_col_name); //not using f this is just to test, fault still occurs
  //removing the row above stops the error occuring


}

Answer 1

嗯，这花了我一段时间，但我通过检查树符是否有效来消除这些信息。

`void fileForm::on_treeview_selected()
{

  Gtk::TreeIter treeiter = m_treeSelection->get_selected();
  if (treeiter) {
    Gtk::TreeModel::Row row = *treeiter;
    m_filename = row.get_value(m_columns.m_col_name);
  }

}`

似乎on_treeView_selected()必须在没有导致错误的有效选择的情况下被调用。