### Class

# Gtk.TreeModelSort

#### Description [src]

```
class Gtk.TreeModelSort : GObject.Object {
parent: GObject
}
```

A GtkTreeModel which makes an underlying tree model sortable

The `GtkTreeModelSort`

is a model which implements the `GtkTreeSortable`

interface. It does not hold any data itself, but rather is created with
a child model and proxies its data. It has identical column types to
this child model, and the changes in the child are propagated. The
primary purpose of this model is to provide a way to sort a different
model without modifying it. Note that the sort function used by
`GtkTreeModelSort`

is not guaranteed to be stable.

The use of this is best demonstrated through an example. In the
following sample code we create two `GtkTreeView`

widgets each with a
view of the same data. As the model is wrapped here by a
`GtkTreeModelSort`

, the two `GtkTreeViews`

can each sort their
view of the data without affecting the other. By contrast, if we
simply put the same model in each widget, then sorting the first would
sort the second.

## Using a `GtkTreeModelSort`

```
{
GtkTreeView *tree_view1;
GtkTreeView *tree_view2;
GtkTreeModel *sort_model1;
GtkTreeModel *sort_model2;
GtkTreeModel *child_model;
// get the child model
child_model = get_my_model ();
// Create the first tree
sort_model1 = gtk_tree_model_sort_new_with_model (child_model);
tree_view1 = gtk_tree_view_new_with_model (sort_model1);
// Create the second tree
sort_model2 = gtk_tree_model_sort_new_with_model (child_model);
tree_view2 = gtk_tree_view_new_with_model (sort_model2);
// Now we can sort the two models independently
gtk_tree_sortable_set_sort_column_id (GTK_TREE_SORTABLE (sort_model1),
COLUMN_1, GTK_SORT_ASCENDING);
gtk_tree_sortable_set_sort_column_id (GTK_TREE_SORTABLE (sort_model2),
COLUMN_1, GTK_SORT_DESCENDING);
}
```

To demonstrate how to access the underlying child model from the sort
model, the next example will be a callback for the `GtkTreeSelection`

`GtkTreeSelection::changed`

signal. In this callback, we get a string
from COLUMN_1 of the model. We then modify the string, find the same
selected row on the child model, and change the row there.

## Accessing the child model of in a selection changed callback

```
void
selection_changed (GtkTreeSelection *selection, gpointer data)
{
GtkTreeModel *sort_model = NULL;
GtkTreeModel *child_model;
GtkTreeIter sort_iter;
GtkTreeIter child_iter;
char *some_data = NULL;
char *modified_data;
// Get the current selected row and the model.
if (! gtk_tree_selection_get_selected (selection,
&sort_model,
&sort_iter))
return;
// Look up the current value on the selected row and get
// a new value to change it to.
gtk_tree_model_get (GTK_TREE_MODEL (sort_model), &sort_iter,
COLUMN_1, &some_data,
-1);
modified_data = change_the_data (some_data);
g_free (some_data);
// Get an iterator on the child model, instead of the sort model.
gtk_tree_model_sort_convert_iter_to_child_iter (GTK_TREE_MODEL_SORT (sort_model),
&child_iter,
&sort_iter);
// Get the child model and change the value of the row. In this
// example, the child model is a GtkListStore. It could be any other
// type of model, though.
child_model = gtk_tree_model_sort_get_model (GTK_TREE_MODEL_SORT (sort_model));
gtk_list_store_set (GTK_LIST_STORE (child_model), &child_iter,
COLUMN_1, &modified_data,
-1);
g_free (modified_data);
}
```

#### Constructors

###### gtk_tree_model_sort_new_with_model

Creates a new `GtkTreeModelSort`

, with `child_model`

as the child model.

#### Instance methods

###### gtk_tree_model_sort_clear_cache

This function should almost never be called. It clears the `tree_model_sort`

of any cached iterators that haven’t been reffed with
`gtk_tree_model_ref_node()`

. This might be useful if the child model being
sorted is static (and doesn’t change often) and there has been a lot of
unreffed access to nodes. As a side effect of this function, all unreffed
iters will be invalid.

###### gtk_tree_model_sort_convert_child_iter_to_iter

Sets `sort_iter`

to point to the row in `tree_model_sort`

that corresponds to
the row pointed at by `child_iter`

. If `sort_iter`

was not set, `FALSE`

is returned. Note: a boolean is only returned since 2.14.

###### gtk_tree_model_sort_convert_child_path_to_path

Converts `child_path`

to a path relative to `tree_model_sort`

. That is,
`child_path`

points to a path in the child model. The returned path will
point to the same row in the sorted model. If `child_path`

isn’t a valid
path on the child model, then `NULL`

is returned.

###### gtk_tree_model_sort_convert_iter_to_child_iter

Sets `child_iter`

to point to the row pointed to by `sorted_iter`

.

###### gtk_tree_model_sort_convert_path_to_child_path

Converts `sorted_path`

to a path on the child model of `tree_model_sort`

.
That is, `sorted_path`

points to a location in `tree_model_sort`

. The
returned path will point to the same location in the model not being
sorted. If `sorted_path`

does not point to a location in the child model,
`NULL`

is returned.

###### gtk_tree_model_sort_get_model

Returns the model the `GtkTreeModelSort`

is sorting.

###### gtk_tree_model_sort_iter_is_valid

This function is slow. Only use it for debugging and/or testing purposes.

###### gtk_tree_model_sort_reset_default_sort_func

This resets the default sort function to be in the “unsorted” state. That
is, it is in the same order as the child model. It will re-sort the model
to be in the same order as the child model only if the `GtkTreeModelSort`

is in “unsorted” state.

##### Methods inherited from GtkTreeDragSource (3)

###### gtk_tree_drag_source_drag_data_delete

Asks the `GtkTreeDragSource`

to delete the row at `path`

, because
it was moved somewhere else via drag-and-drop. Returns `FALSE`

if the deletion fails because `path`

no longer exists, or for
some model-specific reason. Should robustly handle a `path`

no
longer found in the model!

###### gtk_tree_drag_source_drag_data_get

Asks the `GtkTreeDragSource`

to return a `GdkContentProvider`

representing
the row at `path`

. Should robustly handle a `path`

no
longer found in the model!

###### gtk_tree_drag_source_row_draggable

Asks the `GtkTreeDragSource`

whether a particular row can be used as
the source of a DND operation. If the source doesn’t implement
this interface, the row is assumed draggable.

##### Methods inherited from GtkTreeModel (28)

##### Methods inherited from GtkTreeSortable (6)

###### gtk_tree_sortable_get_sort_column_id

Fills in `sort_column_id`

and `order`

with the current sort column and the
order. It returns `TRUE`

unless the `sort_column_id`

is
`GTK_TREE_SORTABLE_DEFAULT_SORT_COLUMN_ID`

or
`GTK_TREE_SORTABLE_UNSORTED_SORT_COLUMN_ID`

.

###### gtk_tree_sortable_has_default_sort_func

Returns `TRUE`

if the model has a default sort function. This is used
primarily by GtkTreeViewColumns in order to determine if a model can
go back to the default state, or not.

###### gtk_tree_sortable_set_default_sort_func

Sets the default comparison function used when sorting to be `sort_func`

.
If the current sort column id of `sortable`

is
`GTK_TREE_SORTABLE_DEFAULT_SORT_COLUMN_ID`

, then the model will sort using
this function.

###### gtk_tree_sortable_set_sort_column_id

Sets the current sort column to be `sort_column_id`

. The `sortable`

will
resort itself to reflect this change, after emitting a
`GtkTreeSortable::sort-column-changed`

signal. `sort_column_id`

may either be
a regular column id, or one of the following special values:

###### gtk_tree_sortable_set_sort_func

Sets the comparison function used when sorting to be `sort_func`

. If the
current sort column id of `sortable`

is the same as `sort_column_id`

, then
the model will sort using this function.

###### gtk_tree_sortable_sort_column_changed

Emits a `GtkTreeSortable::sort-column-changed`

signal on `sortable`

.