Question

I am displaying a SaveFileDialog and when OK is clicked I am creating new file, writing some default content to it and then attempting to Open it via the OpenFile() method of the SaveFileDialog. However, the moment I call OpenFile() the content of the file are deleted.

SaveFileDialog saveFileDialog = new SaveFileDialog();
saveFileDialog.Filter = "XML files (*.xml)|*.xml";
saveFileDialog.RestoreDirectory = true;

if (saveFileDialog.ShowDialog() == System.Windows.Forms.DialogResult.OK)
{
    // First Event Creates file and writes default content to it - works ok 
    NewFileCreated( this, new FileCreatedEventArgs() { Template = Template.BBMF, FilePath = saveFileDialog.FileName } );
    // Second Event clears file content as soon as saveFileDialog.OpenFile() called
    FileLoaded( this, new FileLoadedEventArgs() { FileStream = saveFileDialog.OpenFile() } );
}

Can someone explain why this happens and what I need to be doing to successfully Open the newly created file?

Answer 1

According to MSDN, SaveFileDialog.OpenFile()

Caution

For security purposes, this method creates a new file with the
selected name and opens it with read/write permissions. This can cause
unintentional loss of data if you select an existing file to save to.
To save data to an existing file while retaining existing data, use
the File class to open the file using the file name returned in the
FileName property.