Refreshing Live Chart on button click event - wpf

Question

I have Live Chart that I am trying to perform a fresh of the values on Button_Click event but the Chart is not refreshing.
I have two TextBoxes where the user can select the start and end date they would like to review and use the butn_ExecuteQuery_Click to display the data.
public HBDBreakdown()
{
InitializeComponent();
ChartValues();
}
private void ChartValues()
{
try
{
// Defines the variable for differnt lines.
List<double> SmallCommercialIndustValues = new List<double>();
List<double> ResidentialValues = new List<double>();
List<string> AnalystName = new List<string>();
SqlConnection connection = new SqlConnection("Data Source=WINDOWS-B1AT5HC\\MSSQLSERVER2;Initial Catalog=CustomerRelations;user id=sa; password=Westside2$; Integrated Security=False;");
string selectQuery = ("SELECT Users.TX_EMPLOYEE, SUM(CASE WHEN d .REV_CLS <> 2 THEN 1 ELSE 0 END) AS Residential, SUM(CASE WHEN d .REV_CLS = 2 THEN 1 ELSE 0 END) AS SmallCommercialIndust FROM hb_Disputes AS d INNER JOIN Users ON d.ASSGNTO = Users.KY_USER_ID WHERE(d.OPENED >=#OPENED) AND(d.OPENED < #CLOSED) GROUP BY Users.TX_EMPLOYEE; ");
connection.Open();
SqlCommand command = new SqlCommand(selectQuery, connection);
command.Parameters.Add("#OPENED", SqlDbType.DateTime).Value = dtepicker_Open.Text;
command.Parameters.Add("#CLOSED", SqlDbType.DateTime).Value = dtepicker_DateResolved.Text;
SqlDataReader sqlReader = command.ExecuteReader();
while (sqlReader.Read())
{
// Check for DBNull and then assign the variable
if (sqlReader["SmallCommercialIndust"] != DBNull.Value)
SmallCommercialIndustValues.Add(Convert.ToInt32(sqlReader["SmallCommercialIndust"]));
// Check for DBNull and then assign the variable
if (sqlReader["Residential"] != DBNull.Value)
ResidentialValues.Add(Convert.ToInt32(sqlReader["Residential"]));
// Check for DBNull and then assign the variable
AnalystName.Add(Convert.ToString(sqlReader["TX_EMPLOYEE"]));
}
SeriesCollection = new SeriesCollection
{
new StackedColumnSeries
{
Title = "Residential",
Values = new ChartValues<double>(ResidentialValues),
StackMode = StackMode.Values, // this is not necessary, values is the default stack mode
DataLabels = true
},
new StackedColumnSeries
{
Title = "Small Commercial Indust",
Values = new ChartValues<double>(SmallCommercialIndustValues),
StackMode = StackMode.Values,
DataLabels = true
}
};
Labels = AnalystName.ToArray();
//Formatter = value => value + " Disputes";
DataContext = this;
}
catch (Exception ex)
{
MessageBox.Show(ex.Message);
}
}
public SeriesCollection SeriesCollection { get; set; }
public string[] Labels { get; set; }
public Func<double, string> Formatter { get; set; }
private void butn_ExecuteQuery_Click(object sender, RoutedEventArgs e)
{
// Refresh Chart
ChartValues();
}

Answer 1

Set DataContext = null; before you call ChartValues() or implement INotifyPropertyChanged and raise the PropertyChanged event from the setters of the source properties.

Answer 2

Better never reset the DataContext only to update the data binding of certain properties. This results in very bad performance as the complete view will be forced to render again. The DataContext is also inherited down the element tree.
Better write cleaner code and handle dynamic data more gracefully and as intended by the framework (see Data Binding Overview).
Inside a control (or on a DependencyObject in general) you should always implement all properties that are involved in data binding as DependencyProperty.
They will automatically refresh the target and depending on the Binding.Mode also the source of the specific Binding.
Since you are reassigning SeriesCollection and Labels, both properties should be a DependencyProperty.
In your case, you can go without implementing dependency properties, because you are only updating collections. So simply avoid reassigning a new collection on each refresh and instead use IList.Clear and IList.Add on collections that implement INotifyCollectionChanged.
SeriesCollection already implements INotifyCollectionChanged, so you only need to change the type of the Labels property from string[] to ObservableCollection<string>. This way IList.Clear and IList.Add operations will be automatically reflected by the binding target (the chart control):
public SeriesCollection SeriesCollection { get; set; }
public ObservableCollection<string> Labels { get; set; }
public HBDBreakdown()
{
InitializeComponent();
// Set the `DataContext` once in the constructor
this.DataContext = this;
// Initialize the collection to prepare them for dynamic clear/add
this.SeriesCollection = new SeriesCollection();
this.Labels = new ObservableCollection<string>();
}
private void ChartValues()
{
try
{
...
this.SeriesCollection.Clear();
this.SeriesCollection.Add(
new StackedColumnSeries
{
Title = "Residential",
Values = new ChartValues<double>(ResidentialValues),
StackMode = StackMode.Values, // this is not necessary, values is the default stack mode
DataLabels = true
});
this.SeriesCollection.Add(
new StackedColumnSeries
{
Title = "Small Commercial Indust",
Values = new ChartValues<double>(SmallCommercialIndustValues),
StackMode = StackMode.Values,
DataLabels = true
});
this.Labels.Clear();
AnalystName.ForEach(this.Labels.Add);
}
// Code smell: never catch 'Exception'.
// Only catch explicitly those exception you can handle.
// A user can't handle exceptions, so in a real business application you wouldn't show the exception message to the user.
catch (Exception ex)
{
// Bad practice
MessageBox.Show(ex.Message);
}
}
Please also read: Exceptions and Exception Handling, especially Exceptions Overview and Design Guidelines for Exceptions.