Python: Check if file was saved

Question

I want to be able to check if the working .blend file has been saved when a user presses a button. If it has not been, Blender should give an error.

I just want the user to save before running my add-on.

@RayMairlot I don't quite understand why this isn't specifically about Blender, as he is asking how to determine (from within Blender, using Blender's UI) if a Blender file has been saved. — PGmath, Jul 27 '16 at 16:09
@PGmath I don't think it's relevant that it's done within Blender and I didn't see the button press as a core part of the question (there are other questions already on this). As shown by the answer below, the answer is a purely python (not bpy) solution. — Ray Mairlot, Jul 27 '16 at 16:14
@PGmath I guess I may be misunderstanding the question as it's unclear if the 'file' they're referencing is a blender file and if they mean has it been saved since changes have been made or if the file isn't saved at all. Confirmation from OP would be helpful. — Ray Mairlot, Jul 27 '16 at 16:19
@RayMairlot The former was my impression. So OP please add some further clarification. — PGmath, Jul 27 '16 at 16:20

score 11 · Accepted Answer · edited Apr 13 '17 at 12:57

11

If 'the file' you are referencing is a blender file and you want to know if it has been saved then there are two properties you can check.

If a blender file hasn't been saved at all you can check it's is_saved property as this will be False if it hasn't been saved:

if bpy.data.is_saved:
    #File has been saved. Do something.

(A previous version of this answer instead checked if the filepath property was blank instead - the above is a correction thanks to poor's comment).

For files that have been saved you can check the is_dirty property, which will be True when changes have been made since the last save:

if bpy.data.is_dirty:
    #Changes have been made since the last save. Do something.

To get a button to execute code have a look at Simple way to add button to UI.

For error messages look at Proper way to show users error info in the UI for addons.

edited Apr 13 '17 at 12:57

Community

1

answered Jul 27 '16 at 16:32

Ray Mairlot

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This is just what I needed. I already know how to add a button. – John Roper Jul 28 '16 at 12:58
Nitpicking: Using is_saved flag is probably the better option to check if the file is saved - Has the current session been saved to disk as a .blend file If you really like to go with filepath the comparison operator is not necessary here. You can write if not bpy.data.filepath: to check an empty string, that's easier to understand and more pythonic: http://stackoverflow.com/a/9573259/3091066 – p2or Jul 29 '16 at 16:00
@poor Thanks, don't know how I missed that option but I'll add it in. Also didn't know about the empty string, that's a great tip. – Ray Mairlot Jul 29 '16 at 16:03

score 0 · Answer 2 · answered Jul 28 '16 at 13:00

0

Just to make Ray's answer more specific with my question:

The code should be

if bpy.data.is_dirty:
    print("You must save your file!")
else:
    print("File OK!")

answered Jul 28 '16 at 13:00

John Roper

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score -1 · Answer 3 · answered Jul 27 '16 at 12:51

-1

This isn't really a blender question, but more a python question. But anyway, this would do the trick:

from os.path import isfile

if not isfile( PathOfSavedFile ): # Check if file exists
    raise IOError( "file <%s> not saved" % PathOfSavedFile )

answered Jul 27 '16 at 12:51

TLousky

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Python: Check if file was saved

3 Answers3