// Add the selected field in the "group by" list to the "order by" list
private void AddSortFieldClicked(object sender, EventArgs e)
{
// Verify that there is a selected field in the "group by" list
if (GroupFieldsListBox.SelectedItem == null)
{
return;
}
// Get the name of the selected field and ensure that it's in the list of selected group fields (checked on in the list, e.g.)
string selectedFieldName = GroupFieldsListBox.SelectedItem.ToString();
if (!_groupByFields.Contains(selectedFieldName))
{
((Page)Parent).DisplayAlert("Only fields used for grouping can be used to order results.", "Query", "OK");
return;
}
// Verify that the field isn't already in the "order by" list
OrderFieldOption existingOrderBy = _orderByFields.FirstOrDefault(field => field.OrderInfo.FieldName == selectedFieldName);
if (existingOrderBy == null)
{
// Create a new OrderBy for this field and add it to the collection (default to ascending sort order)
OrderBy newOrderBy = new OrderBy(selectedFieldName, SortOrder.Ascending);
OrderFieldOption orderField = new OrderFieldOption(false, newOrderBy);
_orderByFields.Add(orderField);
}
}
// Toggle the sort order (ascending/descending) for the field selected in the sort fields list
private void ChangeFieldSortOrder(object sender, EventArgs e)
{
// Verify that there is a selected sort field in the list
OrderFieldOption selectedSortField = OrderByFieldsListBox.SelectedItem as OrderFieldOption;
if (selectedSortField == null)
{
return;
}
// Create a new order field info to define the sort for the selected field
OrderBy newOrderBy = new OrderBy(selectedSortField.OrderInfo.FieldName, selectedSortField.OrderInfo.SortOrder);
OrderFieldOption newSortDefinition = new OrderFieldOption(true, newOrderBy);
// Toggle the sort order from the current value
if (newSortDefinition.OrderInfo.SortOrder == SortOrder.Ascending)
{
newSortDefinition.OrderInfo.SortOrder = SortOrder.Descending;
}
else
{
newSortDefinition.OrderInfo.SortOrder = SortOrder.Ascending;
}
// Add the new OrderBy at the same location in the collection and remove the old one
_orderByFields.Insert(_orderByFields.IndexOf(selectedSortField), newSortDefinition);
_orderByFields.Remove(selectedSortField);
}
// Handle the dismiss event on the dialog to raise a custom event that passes the updated order fields back
public override void OnDismiss(IDialogInterface dialog)
{
base.OnDismiss(dialog);
// Verify the event has listeners
if (OrderFieldDialogClosed != null)
{
// Get an array of checked list item positions (indices)
SparseBooleanArray checkedItemsArray = _orderFieldsListView.CheckedItemPositions;
// Loop through all the available order fields
for (int i = 0; i < _potentialOrderByFields.Count; i++)
{
// Initially set each order option to false
OrderFieldOption orderOption = _potentialOrderByFields[i];
orderOption.OrderWith = false;
// If the item was checked in the list view, set the order option to true
if (checkedItemsArray.KeyAt(i) == i && checkedItemsArray.ValueAt(i))
{
orderOption.OrderWith = true;
}
}
// Raise the event and pass back the updated list of order field options
OrderFieldDialogClosed(this, _potentialOrderByFields);
}
}
private void OrderBySwitched(object sender, EventArgs e)
{
// Use the control's tag to get the row that was changed
nint index = (sender as UISwitch).Tag;
// Get the corresponding field and update it's choice as a sort field
OrderFieldOption orderByOption = _potentialOrderByFields.ElementAt((int)index);
orderByOption.OrderWith = (sender as UISwitch).On;
}
// Remove the selected field from the list of "order by" fields
private void RemoveSortFieldClicked(object sender, EventArgs e)
{
// Verify that there is a selected item in the "order by" list
if (OrderByFieldsListBox.SelectedItem == null)
{
return;
}
// Get the selected OrderFieldOption object and remove it from the collection
OrderFieldOption selectedOrderBy = OrderByFieldsListBox.SelectedItem as OrderFieldOption;
_orderByFields.Remove(selectedOrderBy);
}
private void ShowGroupFields(object sender, EventArgs e)
{
// Create a dialog for choosing fields to group results with
GroupFieldsDialog groupFieldsDialog = new GroupFieldsDialog(_groupByFields);
// Handle the dialog closing event to read the selected fields
groupFieldsDialog.GroupFieldDialogClosed += (s, args) =>
{
// Update the dictionary of group fields from the dialog
_groupByFields = args;
// Get the current list of group fields and create/update the sort field choices
// (only fields selected for grouping can be used to order results)
List <KeyValuePair <string, bool> > currentGroupFields = _groupByFields.Where(field => field.Value == true).ToList();
// Loop through the group fields
foreach (KeyValuePair <string, bool> groupField in currentGroupFields)
{
// Check if this field is missing from the current sort field options
OrderFieldOption existingOption = _orderByFields.Find((opt) => opt.OrderInfo.FieldName == groupField.Key);
if (existingOption == null)
{
// If the field is missing, create a new OrderFieldOption and add it to the list
existingOption = new OrderFieldOption(false, new OrderBy(groupField.Key, SortOrder.Ascending));
_orderByFields.Add(existingOption);
}
}
// Also make sure to remove any 'order by' fields that were removed from the 'group by' list
for (int i = _orderByFields.Count - 1; i >= 0; i--)
{
// If the order by field is not also one of the group fields, remove it from the list
OrderFieldOption opt = _orderByFields.ElementAt(i);
KeyValuePair <string, bool> existingGroupField = currentGroupFields.FirstOrDefault(field => field.Key == opt.OrderInfo.FieldName);
if (existingGroupField.Key == null)
{
_orderByFields.RemoveAt(i);
}
}
};
// Begin a transaction to show a UI fragment (group fields dialog)
FragmentTransaction trans = FragmentManager.BeginTransaction();
groupFieldsDialog.Show(trans, "group_flds");
}
// Show fields the user can choose to sort results with (must be one of the group by fields)
private void ShowOrderByFields(object sender, EventArgs e)
{
// Create a new table
UITableViewController sortFieldsTable = new UITableViewController(UITableViewStyle.Plain);
// Get the current list of group fields and create/update the sort field choices
IEnumerable <KeyValuePair <string, bool> > sortFieldChoices = _groupByFields.Where(field => field.Value);
foreach (KeyValuePair <string, bool> sortChoice in sortFieldChoices)
{
// If this group field is not in the list of available order fields, add it to the list
OrderFieldOption existingOption = _orderByFields.Find(opt => opt.OrderInfo.FieldName == sortChoice.Key);
if (existingOption == null)
{
existingOption = new OrderFieldOption(false, new OrderBy(sortChoice.Key, SortOrder.Ascending));
_orderByFields.Add(existingOption);
}
}
// Also make sure to remove any order by fields that were removed as 'group by' fields
for (int i = _orderByFields.Count - 1; i >= 0; i--)
{
// If this field is not in the grouped field list, remove it from the order fields list
OrderFieldOption opt = _orderByFields.ElementAt(i);
KeyValuePair <string, bool> existingGroupField = sortFieldChoices.FirstOrDefault(field => field.Key == opt.OrderInfo.FieldName);
if (existingGroupField.Key == null)
{
_orderByFields.RemoveAt(i);
}
}
// Create an instance of a custom data source to show the order fields
OrderByFieldsDataSource sortFieldsDataSource = new OrderByFieldsDataSource(_orderByFields);
// Set the data source on the table
sortFieldsTable.TableView.Source = sortFieldsDataSource;
// Show the table view
NavigationController.PushViewController(sortFieldsTable, true);
}
// Handle when the switch for a "group by" field is toggled on or off by adding or removing the field from the collection
private void GroupFieldCheckChanged(object sender, EventArgs e)
{
// Get the check box that raised the event (group field)
Switch groupFieldCheckBox = (Switch)sender;
// Get the field name
string fieldName = groupFieldCheckBox.BindingContext.ToString();
// See if the field is being added or removed from the "group by" list
bool fieldAdded = groupFieldCheckBox.IsToggled;
// See if the field already exists in the "group by" list
bool fieldIsInList = _groupByFields.Contains(fieldName);
// If the field is being added, and is NOT in the list, add it ...
if (fieldAdded && !fieldIsInList)
{
_groupByFields.Add(fieldName);
// Also add it to the "order by" list
OrderBy orderBy = new OrderBy(fieldName, SortOrder.Ascending);
OrderFieldOption orderOption = new OrderFieldOption(false, orderBy);
_orderByFields.Add(orderOption);
}
// If the field is being removed and it IS in the list, remove it ...
else if (!fieldAdded && fieldIsInList)
{
_groupByFields.Remove(fieldName);
// Also check for this field in the "order by" list and remove if necessary (only group fields can be used to order results)
OrderFieldOption orderBy = _orderByFields.FirstOrDefault(field => field.OrderInfo.FieldName == fieldName);
if (orderBy != null)
{
// Remove the field from the "order by" list
_orderByFields.Remove(orderBy);
}
}
}
