How to add custom property to bone in pose mode with python?

Question

I want to create custom property for a bone in "pose mode" and then make it drive a shape key on mesh. As there are lots of shape keys and I need to apply this to every rig I want to script it.

Answer 1

1st Method

1. Assign a custom property to an existing type

   "type" are blender data types please note that "Bone" is different from "PoseBone" type "custom_float2" is just random name it can be anything you like

   bpy.types.PoseBone.custom_float2 = bpy.props.FloatProperty(name="Test Prob", default=0.3, min=0.0, max=1)

   For more description on Creation of Custom property

2. Then Assign it to the bone you wish to use it with

   bpy.data.objects["Armature"].pose.bones["Bone"].custom_float2 = 2.0

   • Select the bone in pose mode and you will see the custom property

   • Note: bones["Bone"].custom_float2 is unique from bones["Bone 2"].custom_float2 and bones["Bone 3"].custom_float2 just you have to repeat step 2 to assing custom property to other bones

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2nd Method

Create the property. Assigning some value is very important.

pbone = bpy.data.objects["Armature"].pose.bones["Bone"]
pbone['myControl'] = 0

Now as Jerryno pointed To change min, max, softmin or softmax you need to adjust the _RNA_UI_ dictionary with those parameters. There are few things have to be kept in mind.

_RNA_UI is a single dictionary for all ID-Properties for any given object.

we have to check if this _RNA_UI dictionary exists if not create

if "_RNA_UI" not in pbone.keys():
            pbone["_RNA_UI"] = {}

And we have to use update() method to append this dictionary

pbone["_RNA_UI"].update({"myControl": {"min":0.0, "max":1.0, "soft_min":0.0, "soft_max":1.0}})