wx.dataview.DataViewModel¶

wx.dataview.DataViewModel is the base class for all data model to be displayed by a wx.dataview.DataViewCtrl.

All other models derive from it and must implement its pure virtual functions in order to define a complete data model. In detail, you need to override wx.dataview.DataViewModel.IsContainer , wx.dataview.DataViewModel.GetParent , wx.dataview.DataViewModel.GetChildren , and wx.dataview.DataViewModel.GetValue in order to define the data model which acts as an interface between your actual data and the wx.dataview.DataViewCtrl.

Note that wx.dataview.DataViewModel does not define the position or index of any item in the control because different controls might display the same data differently. wx.dataview.DataViewModel does provide a wx.dataview.DataViewModel.Compare method which the wx.dataview.DataViewCtrl may use to sort the data either in conjunction with a column header or without (see wx.dataview.DataViewModel.HasDefaultCompare ).

wx.dataview.DataViewModel (as indeed the entire wx.dataview.DataViewCtrl code) is using Variant to store data and its type in a generic way. Variant can be extended to contain almost any data without changes to the original class. To a certain extent, you can use (the somewhat more elegant) Any instead of Variant as there is code to convert between the two, but it is unclear what impact this will have on performance.

Since you will usually allow the wx.dataview.DataViewCtrl to change your data through its graphical interface, you will also have to override wx.dataview.DataViewModel.SetValue which the wx.dataview.DataViewCtrl will call when a change to some data has been committed.

If the data represented by the model is changed by something else than its associated wx.dataview.DataViewCtrl, the control has to be notified about the change. Depending on what happened you need to call one of the following methods:

wx.dataview.DataViewModel.ValueChanged ,
wx.dataview.DataViewModel.ItemAdded ,
wx.dataview.DataViewModel.ItemDeleted ,
wx.dataview.DataViewModel.ItemChanged ,
wx.dataview.DataViewModel.Cleared .

There are plural forms for notification of addition, change or removal of several item at once. See:

wx.dataview.DataViewModel.ItemsAdded ,
wx.dataview.DataViewModel.ItemsDeleted ,
wx.dataview.DataViewModel.ItemsChanged .

Note that Cleared can be called for all changes involving many, or all, of the model items and not only for deleting all of them (i.e. clearing the model).

This class maintains a list of wx.dataview.DataViewModelNotifier which link this class to the specific implementations on the supported platforms so that e.g. calling wx.dataview.DataViewModel.ValueChanged on this model will just call wx.dataview.DataViewModelNotifier.ValueChanged for each notifier that has been added. You can also add your own notifier in order to get informed about any changes to the data in the list model.

Currently wxWidgets provides the following models apart from the base model: wx.dataview.DataViewIndexListModel, wx.dataview.DataViewVirtualListModel, wx.dataview.DataViewTreeStore, wx.dataview.DataViewListStore.

Note that wx.dataview.DataViewModel is reference counted, derives from wx.RefCounter and cannot be deleted directly as it can be shared by several DataViewCtrls. This implies that you need to decrease the reference count after associating the model with a control like this:

musicCtrl = wx.dataview.DataViewCtrl(self, wx.ID_ANY)
musicModel = MyMusicModel()
musicCtrl.AssociateModel(musicModel)
musicModel.DecRef()  # avoid memory leak !!

# add columns now

A potentially better way to avoid memory leaks is to use ObjectDataPtr

### wxPython does not provide wrappers for wxObjectDataPtr

Class Hierarchy¶

Inheritance diagram for class DataViewModel:

Known Subclasses¶

wx.dataview.DataViewListModel, wx.dataview.DataViewTreeStore

Methods Summary¶

`__init__`	Constructor.
`AddNotifier`	Adds a wx.dataview.DataViewModelNotifier to the model.
`ChangeValue`	Change the value of the given item and update the control to reflect it.
`Cleared`	Called to inform the model that all of its data has been changed.
`Compare`	The compare function to be used by the control.
`GetAttr`	Override this to indicate that the item has special font attributes.
`GetChildren`	Override this so the control can query the child items of an item.
`GetParent`	Override this to indicate which wx.dataview.DataViewItem representing the parent of item or an invalid wx.dataview.DataViewItem if the root item is the parent item.
`GetValue`	Override this to indicate the value of item.
`HasContainerColumns`	Override this method to indicate if a container item merely acts as a headline (or for categorisation) or if it also acts a normal item with entries for further columns.
`HasDefaultCompare`	Override this to indicate that the model provides a default compare function that the control should use if no wx.dataview.DataViewColumn has been chosen for sorting.
`HasValue`	Return `True` if there is a value in the given column of this item.
`IsContainer`	Override this to indicate if item is a container, i.e. if it can have child items.
`IsEnabled`	Override this to indicate that the item should be disabled.
`IsListModel`
`IsVirtualListModel`
`ItemAdded`	Call this to inform the model that an item has been added to the data.
`ItemChanged`	Call this to inform the model that an item has changed.
`ItemDeleted`	Call this to inform the model that an item has been deleted from the data.
`ItemsAdded`	Call this to inform the model that several items have been added to the data.
`ItemsChanged`	Call this to inform the model that several items have changed.
`ItemsDeleted`	Call this to inform the model that several items have been deleted.
`RemoveNotifier`	Remove the notifier from the list of notifiers.
`Resort`	Call this to initiate a resort after the sort function has been changed.
`SetValue`	This gets called in order to set a value in the data model.
`ValueChanged`	Call this to inform this model that a value in the model has been changed.
`~wxDataViewModel`	Destructor.

Class API¶

class wx.dataview.DataViewModel(RefCounter)¶

Possible constructors:

DataViewModel()

DataViewModel is the base class for all data model to be displayed by a DataViewCtrl.

Methods¶

__init__(self)¶: Constructor.

AddNotifier(self, notifier)¶

Adds a wx.dataview.DataViewModelNotifier to the model.

Parameters: notifier (wx.dataview.DataViewModelNotifier) –

ChangeValue(self, variant, item, col)¶

Change the value of the given item and update the control to reflect it.

This function simply calls SetValue and, if it succeeded, ValueChanged .

Parameters

variant (DVCVariant) – The new value.
item (wx.dataview.DataViewItem) – The item (row) to update.
col (int) – The column to update.

Return type

bool

Returns

True if both SetValue and ValueChanged returned True.

New in version 2.9.1.

Cleared(self)¶

Called to inform the model that all of its data has been changed.

This method should be called if so many of the model items have changed, that the control should just reread all of them, repopulating itself entirely.

Note that, contrary to the name of the method, it doesn’t necessarily indicate that model has become empty – although this is the right method to call, rather than ItemsDeleted , if it was indeed cleared, which explains the origin of its name.

Return type: bool

Compare(self, item1, item2, column, ascending)¶

The compare function to be used by the control.

The default compare function sorts most data types implemented by Variant (i.e. bool, int, long, double, string) as well as datetime and wx.dataview.DataViewIconText. Override this method to implement a different sorting behaviour or override just DoCompareValues to extend it to support other Variant types.

The function should return negative, null or positive for an ascending comparison, depending on whether the first item is less than, equal to or greater than the second one. The reverse is True for descending comparisons. The items should be compared using the appropriate type for the column passed.

Parameters

item1 (wx.dataview.DataViewItem) – First item to compare.
item2 (wx.dataview.DataViewItem) – Second item to compare.
column (int) – The column holding the items to be compared. If the model class overrides HasDefaultCompare to return True, this parameter will be
ascending (bool) – Indicates whether the sort is being performed in ascending or descending order.

Return type

int

Returns

For an ascending comparison: a negative value if the item1 is less than (i.e. should appear above) item2, zero if the two items are equal or a positive value if item1 is greater than (i.e. should appear below) the second one. The reverse for a descending comparison.

Note

If there can be multiple rows with the same value, consider differentiating them form each other by their IDs rather than returning zero. This to prevent rows with the same value jumping positions when items are added etc. For example:

obj1 = self.ItemToObject(item1)
obj2 = self.ItemToObject(item2)
if obj1[column] == obj2[column]:
    return 1 if ascending == (item1.GetId() > item2.GetId()) else -1
else:
    return 1 if ascending == (obj1[column] > obj2[column]) else -1

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