The gtk.TreeModel interface defines a generic tree interface for use by the gtk.TreeView widget. It is an abstract interface, and is designed to be usable with any appropriate data structure. The programmer just has to implement this interface on their own data type for it to be viewable by a gtk.TreeView widget.

The model is represented as a hierarchical tree of strongly-typed, columned data. In other words, the model can be seen as a tree where every node has different values depending on which column is being queried. The type of data found in a column is determined by using the GType system (ie. G_TYPE_INT, GTK_TYPE_BUTTON, G_TYPE_POINTER, etc). The types are homogeneous per column across all nodes. It is important to note that this interface only provides a way of examining a model and observing changes. The implementation of each individual model decides how and if changes are made.

In order to make life simpler for programmers who do not need to write their own specialized model, two generic models are provided — the gtk.TreeStore and the gtk.ListStore To use these, the developer simply pushes data into these models as necessary. These models provide the data structure as well as all appropriate tree interfaces. As a result, implementing drag and drop, sorting, and storing data is trivial. For the vast majority of trees and lists, these two models are sufficient.

Models are accessed on a node/column level of granularity. One can query for the value of a model at a certain node and a certain column on that node. There are two structures used to reference a particular node in a model. They are the [GtkTreePath-struct|GtkTreePath-struct] and the [GtkTreeIter-struct|GtkTreeIter-struct] (“iter” is short for iterator). Most of the interface consists of operations on a [GtkTreeIter-struct|GtkTreeIter-struct]

A path is essentially a potential node. It is a location on a model that may or may not actually correspond to a node on a specific model. The [GtkTreePath-struct|GtkTreePath-struct] can be converted into either an array of unsigned integers or a string. The string form is a list of numbers separated by a colon. Each number refers to the offset at that level. Thus, the path 0 refers to the root node and the path 2:4 refers to the fifth child of the third node.

By contrast, a [GtkTreeIter-struct|GtkTreeIter-struct] is a reference to a specific node on a specific model. It is a generic struct with an integer and three generic pointers. These are filled in by the model in a model-specific way. One can convert a path to an iterator by calling TreeModel.getIter. These iterators are the primary way of accessing a model and are similar to the iterators used by gtk.TextBuffer They are generally statically allocated on the stack and only used for a short time. The model interface defines a set of operations using them for navigating the model.

It is expected that models fill in the iterator with private data. For example, the gtk.ListStore model, which is internally a simple linked list, stores a list node in one of the pointers. The gtk.TreeModelSort stores an array and an offset in two of the pointers. Additionally, there is an integer field. This field is generally filled with a unique stamp per model. This stamp is for catching errors resulting from using invalid iterators with a model.

The lifecycle of an iterator can be a little confusing at first. Iterators are expected to always be valid for as long as the model is unchanged (and doesn’t emit a signal). The model is considered to own all outstanding iterators and nothing needs to be done to free them from the user’s point of view. Additionally, some models guarantee that an iterator is valid for as long as the node it refers to is valid (most notably the gtk.TreeStore and gtk.ListStore). Although generally uninteresting, as one always has to allow for the case where iterators do not persist beyond a signal, some very important performance enhancements were made in the sort model. As a result, the GTK_TREE_MODEL_ITERS_PERSIST flag was added to indicate this behavior.

To help show some common operation of a model, some examples are provided. The first example shows three ways of getting the iter at the location 3:2:5. While the first method shown is easier, the second is much more common, as you often get paths from callbacks.

Acquiring a [GtkTreeIter-struct|GtkTreeIter-struct]

// Three ways of getting the iter pointing to the location
GtkTreePath *path;
GtkTreeIter iter;
GtkTreeIter parent_iter;

// get the iterator from a string
gtk_tree_model_get_iter_from_string (model,

// get the iterator from a path
path = gtk_tree_path_new_from_string ("3:2:5");
gtk_tree_model_get_iter (model, &iter, path);
gtk_tree_path_free (path);

// walk the tree to find the iterator
gtk_tree_model_iter_nth_child (model, &iter,
NULL, 3);
parent_iter = iter;
gtk_tree_model_iter_nth_child (model, &iter,
&parent_iter, 2);
parent_iter = iter;
gtk_tree_model_iter_nth_child (model, &iter,
&parent_iter, 5);

This second example shows a quick way of iterating through a list and getting a string and an integer from each row. The populate_model() function used below is not shown, as it is specific to the gtk.ListStore For information on how to write such a function, see the gtk.ListStore documentation.

Reading data from a gtk.TreeModel



GtkTreeModel *list_store;
GtkTreeIter iter;
gboolean valid;
gint row_count = 0;

// make a new list_store
list_store = gtk_list_store_new (N_COLUMNS,

// Fill the list store with data
populate_model (list_store);

// Get the first iter in the list, check it is valid and walk
// through the list, reading each row.

valid = gtk_tree_model_get_iter_first (list_store,
while (valid)
gchar *str_data;
gint   int_data;

// Make sure you terminate calls to [gtk.TreeModel.TreeModel.get|TreeModel.get] with a “-1” value
gtk_tree_model_get (list_store, &iter,
STRING_COLUMN, &str_data,
INT_COLUMN, &int_data,

// Do something with the data
g_print ("Row `d:` (`s`,`d`)\n",
row_count, str_data, int_data);
g_free (str_data);

valid = gtk_tree_model_iter_next (list_store,

The gtk.TreeModel interface contains two methods for reference counting: TreeModel.refNode and TreeModel.unrefNode. These two methods are optional to implement. The reference counting is meant as a way for views to let models know when nodes are being displayed. gtk.TreeView will take a reference on a node when it is visible, which means the node is either in the toplevel or expanded. Being displayed does not mean that the node is currently directly visible to the user in the viewport. Based on this reference counting scheme a caching model, for example, can decide whether or not to cache a node based on the reference count. A file-system based model would not want to keep the entire file hierarchy in memory, but just the folders that are currently expanded in every current view.

When working with reference counting, the following rules must be taken into account:

- Never take a reference on a node without owning a reference on its parent. This means that all parent nodes of a referenced node must be referenced as well.

- Outstanding references on a deleted node are not released. This is not possible because the node has already been deleted by the time the row-deleted signal is received.

- Models are not obligated to emit a signal on rows of which none of its siblings are referenced. To phrase this differently, signals are only required for levels in which nodes are referenced. For the root level however, signals must be emitted at all times (however the root level is always referenced when any view is attached).

interface TreeModelIF {}



gulong addOnRowChanged(void delegate(TreePath, TreeIter, TreeModelIF) dlg, ConnectFlags connectFlags)

This signal is emitted when a row in the model has changed.

gulong addOnRowDeleted(void delegate(TreePath, TreeModelIF) dlg, ConnectFlags connectFlags)

This signal is emitted when a row has been deleted.

gulong addOnRowHasChildToggled(void delegate(TreePath, TreeIter, TreeModelIF) dlg, ConnectFlags connectFlags)

This signal is emitted when a row has gotten the first child row or lost its last child row.

gulong addOnRowInserted(void delegate(TreePath, TreeIter, TreeModelIF) dlg, ConnectFlags connectFlags)

This signal is emitted when a new row has been inserted in the model.

gulong addOnRowsReordered(void delegate(TreePath, TreeIter, void*, TreeModelIF) dlg, ConnectFlags connectFlags)

This signal is emitted when the children of a node in the gtk.TreeModel have been reordered.

void foreach_(GtkTreeModelForeachFunc func, void* userData)

Calls func on each node in model in a depth-first fashion.

GType getColumnType(int index)

Returns the type of the column.

GtkTreeModelFlags getFlags()

Returns a set of flags supported by this interface.

int getIter(TreeIter iter, TreePath path)

Sets iter to a valid iterator pointing to path.

bool getIterFirst(TreeIter iter)

Initializes iter with the first iterator in the tree (the one at the path "0") and returns TRUE. Returns FALSE if the tree is empty.

bool getIterFromString(TreeIter iter, string pathString)

Sets iter to a valid iterator pointing to path_string, if it exists. Otherwise, iter is left invalid and FALSE is returned.

int getNColumns()

Returns the number of columns supported by tree_model.

TreePath getPath(TreeIter iter)

Returns a newly-created [GtkTreePath-struct|GtkTreePath-struct] referenced by iter.

string getStringFromIter(TreeIter iter)

Generates a string representation of the iter.

void* getStruct()

the main Gtk struct as a void*

GtkTreeModel* getTreeModelStruct(bool transferOwnership)

Get the main Gtk struct

void getValist(TreeIter iter, void* varArgs)

See TreeModel.get, this version takes a va_list for language bindings to use.

Value getValue(TreeIter iter, int column, Value value)

Initializes and sets value to that at column. When done with value, Value.unset needs to be called to free any allocated memory.

int getValueInt(TreeIter iter, int column)

Get the value of a column as a char array. this is the same calling getValue and get the int from the value object

string getValueString(TreeIter iter, int column)

Get the value of a column as a char array. this is the same calling getValue and get the string from the value object

bool iterChildren(TreeIter iter, TreeIter parent)

Sets iter to point to the first child of parent.

bool iterHasChild(TreeIter iter)

Returns TRUE if iter has children, FALSE otherwise.

int iterNChildren(TreeIter iter)

Returns the number of children that iter has.

bool iterNext(TreeIter iter)

Sets iter to point to the node following it at the current level.

bool iterNthChild(TreeIter iter, TreeIter parent, int n)

Sets iter to be the child of parent, using the given index.

bool iterParent(TreeIter iter, TreeIter child)

Sets iter to be the parent of child.

bool iterPrevious(TreeIter iter)

Sets iter to point to the previous node at the current level.

void refNode(TreeIter iter)

Lets the tree ref the node.

void rowChanged(TreePath path, TreeIter iter)

Emits the row-changed signal on tree_model.

void rowDeleted(TreePath path)

Emits the row-deleted signal on tree_model.

void rowHasChildToggled(TreePath path, TreeIter iter)

Emits the row-has-child-toggled signal on tree_model. This should be called by models after the child state of a node changes.

void rowInserted(TreePath path, TreeIter iter)

Emits the row-inserted signal on tree_model.

void rowsReordered(TreePath path, TreeIter iter, int* newOrder)

Emits the rows-reordered signal on tree_model.

void rowsReorderedWithLength(TreePath path, TreeIter iter, int[] newOrder)

Emits the rows-reordered signal on tree_model.

void unrefNode(TreeIter iter)

Lets the tree unref the node.

Static functions

GType getType()