How to update the dependencies of a driver via python script?

Question

i need to be able to update the dependencies of my drivers via script, does anyone knows how to? thank you very much in advance! my script works on changing the values of the drivers , but sometimes i may need to update

import bpy 
import random # Random floating point number between lo and hi 
def randf(lo, hi): 
    return random.uniform(lo, hi) 
bpy.app.driver_namespace["randf"] = randf

import bpy import random
Random floating point number between lo and hi

def randf(lo, hi): return random.uniform(lo, hi) bpy.app.driver_namespace["randf"] = randf — Francesco Shanigawe Kobane, Sep 14 '18 at 12:20
Can you clarify "driver dependencies" Is what is referred to as the_"update"_ effectively the result of re-running script above, ie setting ranf to another float between 0 and 1, How / when to flag the update? — batFINGER, Sep 14 '18 at 14:51
@batFINGER you know the button "update dependencies" in the driver panel in the graph editor? i wanted to access that one. by the way , somebody already gave me a solution : https://blenderartists.org/t/driver-update-dependencies-via-script/1126347 — Francesco Shanigawe Kobane, Sep 14 '18 at 17:56

score 4 · Answer 1 · edited Sep 16 '18 at 19:47

Here, an awesome guy gave me the solution!

Looking at the source code, the button appears to be a direct function rather than a python operator:
but = uiDefIconTextBut(block, UI_BTYPE_BUT, B_IPO_DEPCHANGE, 
ICON_FILE_REFRESH, IFACE_("Update Dependencies"),
0, 0, 10 * UI_UNIT_X, UI_UNIT_Y,
NULL, 0.0, 0.0, 0, 0,
TIP_("Force updates of dependencies"));
UI_but_func_set(but, driver_update_flags_cb, fcu, NULL);
The way I update a driver in my add-on is by adding and removing a space on the driver’s expression attribute. As far as I could tell, it acts the same way:
driver.expression += " "
driver.expression = driver.expression[:-1]

score 4 · Answer 2 · answered Dec 04 '19 at 20:44

4

When I had the same issue during driving a node group node (mixShader), I solved it by finding the expression in bpy.data and just setting it to the original expression. More or less a same hack as Francesco Shanigawe Kobane, but saves one line.

bpy.data.node_groups["<NodeGroup>"].animation_data.drivers[0].driver.expression = '<expression>'

answered Dec 04 '19 at 20:44

Aventau

51
5

thank you so much @aventau for the answer! gonna try that! – Francesco Shanigawe Kobane Dec 06 '19 at 10:21

How to update the dependencies of a driver via python script?

Random floating point number between lo and hi

2 Answers2