# Programming the Open Button

Now it is time to use those dialogs to program the Open, Save, and Save As buttons in our UI. We shall start by first implementing the Open button by creating a new method called open_file(), which we shall integrate within our connect_events() method.

## Open Button

The open_file() button will obtain access to our current_file entity, which will be updated upon successfully opening the selected file.

# #![allow(unused_variables)]
#fn main() {
pub fn connect_events(self) -> ConnectedApp {
// External state to share across events.
let current_file = Arc::new(RwLock::new(None));

// Connect all of the events that this UI will act upon.
self.open_file(current_file.clone());

// Wrap the App within ConnectedApp to enable the developer to execute the program.
ConnectedApp(self)
}

#}

### connect_clicked()

Now, the open_file method will simply be grabbing references to the editor's source buffer, to write the opened file's data into the buffer; then grabbing a reference to the web view so that we can update it after opening the file; a reference to the header bar so that we can update the title and subtitle; and finally the Open button itself, so that we can map the connect_clicked() event to it.

# #![allow(unused_variables)]
#fn main() {
let editor = self.content.source.buff.clone();
let preview = self.content.preview.clone();
// Program the button here
});
}

#}

### Creating an OpenDialog

Within connect_clicked(), we shall start by creating a new OpenDialog. When opening this dialog, we are to attempt to pass in the current_file's parent directory, if it exists, so that the open file dialog uses that directory in the file search view by default.

Note that I am using if let Some(ref path) rather than a map here due to borrowing concerns -- if you can't get a map to borrow correctly, using a match or if let usually does the trick.

# #![allow(unused_variables)]
#fn main() {
// Create a new open file dialog using the current file's parent
// directory as the preferred directory, if it's set.
let open_dialog = OpenDialog::new({
if let Some(ref path) = *lock {
path.get_dir()
} else {
None
}
});

#}

### Running the Dialog

Once we have our open_dialog variable, it's then just a matter of running the dialog, grabbing the selected file path, and then handling that file accordingly: read the file into the source buffer, update the web view, and then update the title and subtitle.

# #![allow(unused_variables)]
#fn main() {
// Runs the dialog, and opens the file if a file was selected.
if let Some(new_file) = open_dialog.run() {
if let Ok(mut file) = File::open(&new_file) {
// Read the file's contents into an in-memory buffer
let mut contents = String::new();

// Update the title and subtitle
if let Some(parent) = new_file.parent() {
let subtitle: &str = &parent.to_string_lossy();
}

// Set the shared file path as this file.
*current_file.write().unwrap() =

// Update the editor & preview
editor.set_text(&contents);
}
}

#}

### The Completed Code

# #![allow(unused_variables)]
#fn main() {
let editor = self.content.source.buff.clone();
let preview = self.content.preview.clone();
// Create a new open file dialog using the current file's parent
// directory as the preferred directory, if it's set.
let open_dialog = OpenDialog::new({
if let Some(ref path) = *lock {
path.get_dir()
} else {
None
}
});

// Runs the dialog, and opens the file if a file was selected.
if let Some(new_file) = open_dialog.run() {
if let Ok(mut file) = File::open(&new_file) {
// Read the file's contents into an in-memory buffer
let mut contents = String::new();

// Update the title and subtitle
if let Some(parent) = new_file.parent() {
let subtitle: &str = &parent.to_string_lossy();
}

// Set the shared file path as this file.
*current_file.write().unwrap() =
#}