Objet name
Introduction
Tous les objets du programme ont un object name qui les identifie de manière unique dans un Document donné.
Ces informations s'appliquent à tous les objets dérivés de App DocumentObject (classe App::DocumentObject
), qui comprend essentiellement tous les objets qu'il est possible de créer dans un document.
Les Names
Il existe différentes propriétés pour les noms:
- Le
Name
ne peut contenir que des caractères alphanumériques simples et le trait de soulignement,[_0-9a-zA-Z]
. - Le
Name
ne peut pas commencer par un nombre. Il doit commencer par une lettre ou le trait de soulignement,[_a-zA-Z]
. - Le
Name
est attribué au moment de la création de l'objet ensuite, il n'est plus modifiable. L'objet ne peut jamais être renommé. - Le
Name
doit être unique dans tout le document. Peu importe si deux objets sont de types complètement différents, par exemple, l'un est un PartDesign Poche et l'autre est un Arch Mur. Ils doivent avoir des noms différents. - Lors de la création d'un objet du même type, normalement le nom est augmenté d'un numéro séquentiel par exemple
Box
,Box001
,Box002
etc.... Cela permet d'éviter la collusion des noms.. - Une fois l'objet supprimé, son
Name
devient disponible pour être utilisé par un objet nouvellement créé. Cela signifie que siBox
,Box001
etBox002
existent et que nous supprimons le premier élément, la boîte suivante créée avec Part Cube ne sera pasBox003
, ce sera à nouveauBox
, cette chaîne étant disponible pour être réutilisée. Notez qu'il n'est pas possible de renommerBox001
ouBox002
enBox
car leurs noms sont fixes.
In summary, the Name
essentially acts like a unique identifier (UID) for an object. Since a unique Name
is very restrictive, all objects also have a Label
property which allows "renaming" the object to something more descriptive. The internal Name
actually remains fixed, but the user editable Label
can be used in most situations where the Name
would be used. In common usage in the program and the documentation, "renaming" means changing the Label
and not the actual Name
of the object.
Labels
There are various properties for Labels:
- The
Label
can accept any UTF8 string, including accents and spaces. - The tree view actually displays the
Label
of the object, not theName
. Therefore, whenever a new object is created, it is a good practice to change theLabel
to a more descriptive string. To rename (relabel) the object, select it in the tree view and press F2, or open the context menu (right-click) and choose Rename. - Even after an object was renamed (relabelled), the internal
Name
will still be reported in many places, for example, in the status bar or in the selection view, when the object is selected. - Since the internal functions of the program refer to the objects by
Name
, many dialogs will display theName
first, followed by the user editableLabel
in parentheses, for example,Box (Extruded piece)
. - By default the
Label
is unique, just like theName
. However, this behavior can be changed in the preferences editor, Edit → Preferences → General → Document → Allow duplicate object labels in one document. This means that in general theLabel
is not unique in the document, and may actually be repeated. However, the recommendation is to keep theLabel
unique, as this is probably what is most useful to identify different objects. When writing custom functions that manipulate objects, the methods should use theName
of the object rather than itsLabel
to guarantee that the correct object is used.
Label2
This property was introduced in v0.19. It is a simple string that can contain arbitrary text, and therefore can be used for documenting (describing with more detail) the created object.
- In the tree view edit the field next to the icon, under "Description", by clicking on it and pressing F2.
- You can also change this property by modifying the
Label2
attribute from the Python console. - The DonnéesLabel2 attribute is normally hidden in the property editor but can be made visible by opening the context menu (right click) and selecting Show all.
Scripting
See also: FreeCAD Scripting Basics, and scripted objects.
Any object in the software is internally created with the addObject()
method of the document. The majority of 2D and 3D objects that the user will see in the 3D view are derived from a Part Feature. In the following example, the object created is a Part Box.
import FreeCAD as App
doc = App.newDocument()
obj = doc.addObject("Part::Box", "Name")
obj.Label = "Custom label"
Name
The addObject
function has two basic string arguments.
- The first argument indicates the type of object, in this case,
"Part::Box"
. - The second argument is a string that defines the
Name
attribute. If it is not provided, it defaults to the same name as the class of the object, that is,"Part__Box"
, where the two invalid symbols, the colons::
, are replaced by two underscores__
.- The
Name
can only include simple alphanumeric characters, and the underscore,[_0-9a-zA-Z]
. If other symbols are given, these will be converted to underscores; for example,"A+B:C*"
is converted to"A_B_C_"
. - The
Name
cannot start with a number; it must start with a letter or the underscore,[_a-zA-Z]
. For example,"123ABC"
is converted to"_23ABC"
. - The
Name
is fixed at creation time; it cannot be modified afterwards. - The
Name
must be unique in the entire document. If the same"Name"
is used, a sequential number will be appended automatically so that the resulting names are unique; for example, if"Name"
already exists, then new objects will be called"Name001"
,"Name002"
,"Name003"
, etc.
- The
Label
The Label
is a property of the created object and can be changed to a more meaningful text.
- Upon creating the object, the
Label
is the same as theName
. - However, unlike the
Name
, theLabel
can accept any UTF8 string, including accents and spaces. - The
Label
can be changed at any point in time just by assigning the desired string,obj.Label = "New label"
Getting an object by Name or Label
All objects in a document are data attributes of the corresponding Document object. The attribute's name correspond to the internal Name
of the object.
import FreeCAD as App
obj1 = App.ActiveDocument.Box
obj2 = App.ActiveDocument.Box001
obj3 = App.ActiveDocument.Box002
This is equivalent to using the getObject
method of the Document.
import FreeCAD as App
obj1 = App.ActiveDocument.getObject('Box')
obj2 = App.ActiveDocument.getObject('Box001')
obj3 = App.ActiveDocument.getObject('Box002')
However, it is also possible to get the object by the more descriptive Label
.
import FreeCAD as App
obj1 = App.ActiveDocument.getObjectsByLabel("Concrete wall")[0]
obj2 = App.ActiveDocument.getObjectsByLabel("Custom parallelepiped")[0]
obj3 = App.ActiveDocument.getObjectsByLabel("Some special name for this cube__002")[0]
Given that the Label
is in general not unique, the getObjectsByLabel
method returns a list with all objects found with that Label
. However, if the Label
is unique in the document then the first element in that list should be the desired object.
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