How to know what enums are valid for an operator?

Coding Python Support
1

Hi,
Could some one help me with a py question?
How can I know what enums an operator can take in an argument?
For example mode changing in 3D view is done by:

bpy.ops.object.mode_set(mode='EDIT', toggle=False)

How do I find out what modes are available for this object type? For example only ‘OBJECT’ is available for lamps, but meshes also have ‘EDIT’ and so on.

Thanks

2

Here are some ways I have done this in the past. Following your example.

  1. Use the wiki. This can be frustrating and you almost have to know what you are searching for beforehand.
    http://www.blender.org/documentation/blender_python_api_2_64_release/bpy.ops.object.html?highlight=bpy.ops.object.edit#bpy.ops.object.editmode_toggle

  2. Try the operator in the console and intentionally make an error in your keyword argument. eg

bpy.ops.object.mode-set(mode = 'What the heck goes here')

will give you back

Traceback (most recent call last):
  File "<blender_console>", line 1, in <module>
  File "C:\Dev\Blender\blender-2.65-r53841-win64\2.65\scripts\modules\bpy\ops.py", line 188, in __call__
    ret = op_call(self.idname_py(), None, kw)
TypeError: Converting py args to operator properties:  enum "What the heck goes here" not found in ('OBJECT', 'EDIT', 'SCULPT', 'VERTEX_PAINT', 'WEIGHT_PAINT', 'TEXTURE_PAINT')

Other than that…I’m not really sure either.

1 Like
3

Thanks, but that way around I know about.

From the “Blender Experimental 2012” key-map I have found the following code that makes a menu with the available modes.

class ModeSwitchMenu(bpy.types.Menu):
    """ A menu for switching between object modes.
    """
    bl_idname = "OBJECT_MT_mode_switch_menu"
    bl_label = "Switch Mode"


    def draw(self, context):
        layout = self.layout
        layout.operator_enum("object.mode_set", "mode")
bpy.utils.register_class(ModeSwitchMenu)




# Temporary work around: Blender does not properly limit the mode switch menu
# items until the first mode switch (e.g. mesh objects will show pose mode as
# an option).
# TODO: file a bug report for this behavior.
bpy.ops.object.mode_set(mode='OBJECT', toggle=False)

So this is almost what I want, but I don´t want the menu.

4

the mode menu is generated by c-code, operator_enum calls a c-code function as well. I don’t see a chance with current API to retrieve the possible modes. You better test all object types and write the modes down.

What do you need this for btw?

5

Here’s an automated approach for getting the available modes (however hacky):

import bpy

modes = bpy.types.OBJECT_OT_mode_set.bl_rna.properties['mode'].enum_items.keys()
ob_types = bpy.types.Object.bl_rna.properties['type'].enum_items.keys()


window = bpy.context.window


obs = []


for ob_type in ob_types:
    if bpy.context.object and bpy.context.object.mode != 'OBJECT':
        bpy.ops.object.mode_set() # object mode
    
    bpy.ops.object.add(type=ob_type)
    ob = bpy.context.object
    obs.append(ob)
    
    modes_available = []
    
    for mode in modes:
        #print(mode, ob_type)
        try:
            bpy.ops.object.mode_set(mode=mode)
        except TypeError:
            continue
        else:
            modes_available.append(mode)
    print("Object type '%s' supports modes:" % ob_type)
    [print(" -", m) for m in modes_available]
    print()
    
bpy.ops.object.mode_set() # object mode
for ob in obs:
    ob.select = True
bpy.ops.object.delete()
6

A bit hacky, so I think I will just hard code the values.

I´m just exploring the api by implementing a mode-switch similar how to alt + tab works in windows.

7

Nice…that is very handy

8

i got that idea from Bart Crouch’s icon display addon :slight_smile:

https://sites.google.com/site/bartiuscrouch/scripts/icon_display