How to set a property based on an ImportHelper dialog?

Coding Python Support
1

Hello!

I’m working on a little plugin that imports some external data and also creates some Blender objects based on that data. I want to call up the import dialog (with ImportHelper in order to filter by file extension) and save the filepath returned by the import dialog as a property, to be used by other functions. Other functions would parse the filename, and look up some stuff in a little database I have, maybe move some things around that are already in the scene (or not), and also import that file. Alright.

The problem I’m having is that I can’t save the filepath anywhere, and I’m not sure where I should be saving it since I don’t want it attached to a mesh, etc. For example, here’s a snippet:


class SimSceneSettings(bpy.types.PropertyGroup) :
    
    ps_filepath = bpy.props.StringProperty (
        name = "File path for the ps mesh", 
        maxlen = 1024,
        default = ""
    )
# end SimSceneSettings


class PSDialog(Operator, ImportHelper):
    
    bl_idname = "sim_tools.imp_ps"
    bl_label = "PS"
    
    filename_ext = ".x3d"
    
    filter_glob = bpy.props.StringProperty (
        default = "*.x3d",
        options = {'HIDDEN'}
    )
 
    filepath = bpy.props.StringProperty (
        name = "File Path", 
        maxlen = 1024,
        default = ""
    )
    
 
    def execute(self, context) :
        context.scene.sim_tools.ps_filepath = self.properties.filepath
        print("inside execute: ", self.properties.filepath)
        return {'FINISHED'}

This prints the stuff preceded by “inside execute”, but context.scene.sim_tools.ps_filepath is empty after the dialog box returns. I need this property to stay put.

To call up the dialog box, I do Shift+A to call up my toolkit (function add_to_menu referenced below) , which puts one object on the scene at the start. It also draws a panel in the Tool Shelf which has a button which calls up PSDialog. The PropertyGroup is registered under scene, but I’m not sure if that’s correct.


def register() :
    bpy.utils.register_module(__name__)
    bpy.types.Scene.sim_tools = bpy.props.PointerProperty(type = SimSceneSettings)
    bpy.types.INFO_MT_add.prepend(add_to_menu)
# end register

def unregister() :
    del bpy.types.Scene.sim_tools
    bpy.utils.unregister_module(__name__)
    bpy.types.INFO_MT_add.remove(add_to_menu)
# end unregister

I hope this makes sense. I just want to save the filepath from the import dialog somewhere permanent, or at least, somewhere that lives as long as my Tool Shelf panel. Thank you!

2

This works fine for me. I’m assuming your add_to_menu is something similar to


def add_to_menu(self, context):
    self.layout.operator("sim_tools.imp_ps")



inside execute:  F:\blender
odes.crash.x3d



>>> C.scene.sim_tools.ps_filepath
'F:\\blender\
odes.crash.x3d'
3

Not exactly. Here’s some more code - I tried to explain it in words before to be more concise, but maybe it wasn’t clear.

add_to_menu doesn’t reference the file import dialog itself. It adds at least one mesh, as well as a panel in the Tool Shelf to modify that object, which has a button which you press to get the file import dialog. The idea is that, once I have the filename, the plugin will import the x3d file, but it’ll also adjust the size of the one mesh. That’s why I need to get the filename inside the “main” program. Leaving the mesh aside, here’s the relevant code:


class SimToolsStage(bpy.types.Operator) :
    bl_idname = "sim_tools.stage"
    bl_label = "Simulation Tools"
    bl_options = {'REGISTER', 'UNDO'}

    def draw(self, context) :
        layout = self.layout
        layout.operator("sim_tools.imp_ps")
        #this^ is the button that calls up the file import dialog
        #other stuff cut
    #end draw

    def main(self, context) :
        
        if context.scene.sim_tools.ps_filepath == ""  :
            print("FP Empty")
        else :
            print(context.scene.sim_tools.ps_filepath)

       #other stuff cut, incl. calls to another module to draw the mesh
        return {'FINISHED'}
    # end main
    

    def invoke(self, context, event) :
        self.main(context)
        return {'FINISHED'}
    # end invoke
    
    def execute(self, context) :
        self.main(context)
        return {'FINISHED'}
    # end execute
# end SimToolsStage

def add_to_menu(self, context) :
    self.layout.operator("sim_tools.stage", icon = 'PLUGIN')
# end add_to_menu

The problem is that the if statement in the main function always prints “FP Empty”, and if I check the value of context.scene.sim_tools.ps_filepath through the console, it also always says that it’s empty. Thank you.

4

The ImportHelper invokes a the filebrowser. If you don’t use the ImportHelper you need to add this to your invoke of the import op.


context.window_manager.fileselect_add(self)

I’m not sure if this is compatible with the register / undo operator in the op tool panel, and is my guess why your set up isn’t working. You may be able to use a StringProperty(subtype=‘FILE_PATH’) , but that doesn’t allow you to glob files.

5

Thank you for your help! I don’t know why it wasn’t working before, but it works now. I was fiddling around and checked the value of context.scene.sim_tools.ps_filepath through the console, and this time, it wasn’t empty! So, I just added an update function to ps_filepath property, and now it’s all good. Thanks again!