Updating and persisting a material property

R by randomluck on 29 Aug 2022, edited 20 Mar 2024 #

First of all: thanks for the great Tutorials on IfcOpenShell. Without those I wouldn't know where to even begin! Getting that out of the way, I'm very new to the Ifc format and therefore very new to IfcOpenShell.

I have a wall object with a pset attached to the material properties. Now I want to change a value of one of the material properties. In this case it's about "Test2" which should take the value of "Test1". This means I have to a) extract the value of "Test1" (which is 0.629...) and replace the value of "Test2" by exactly that number.

I've managed to do that in Python, however, I don't know how to proceed from there to "persist" or write the ifc file with the new values. This is what my current code looks like:


import ifcopenshell

import ifcopenshell.util

import ifcopenshell.util.element

import ifcopenshell.util.pset

import ifcopenshell.geom


ifc = ifcopenshell.open("./ifc_file.ifc")


materials = ifc.by_type("IfcMaterial")

wall = ifc.by_type("IfcWall")[0]

for material in materials:

        psets = ifcopenshell.util.element.get_psets(material)

        for key, pset in psets.items():

                if key.startswith("HHLA"):

                    print(pset)

                    pset["Test2"] = pset["Test1"]

                    print(pset)

The question is: how exactly do I manage to write an updated ifc file with everything being the same as the old ifc file but the new entries for Test2? When using "write", I end up having the same file which I had before.

If anything is unclear or if there is a much less complicated way to achieve what I want to do, please let me know.

I've uploaded an excerpt of what the IFC file looks like in FZKViewer here: https://community.osarch.org/uploads/editor/1b/zlmpu5jlz2cj.png

M by Moult on 29 Aug 2022 # +1 votes

This should help :)


ifcopenshell.api.run("pset.edit_pset", ifc, pset=pset, properties={"Test2": pset["Test1"}})

# and once you're done...

ifc.write("/path/to/edited.ifc")

R by randomluck on 29 Aug 2022 #

@Moult said:

This should help :)

ifcopenshell.api.run("pset.edit_pset", ifc, pset=pset, properties={"Test2": pset["Test1"]})

and once you're done...

ifc.write("/path/to/edited.ifc")

Hey there! Thanks a lot fo answering this quick and sorry for answering in a very verbose way since I want to make sure that I don't miss the simple way (again) :)

I'm having a type issue when reading in the material properties which end up being a list which doesn't have an attribtue called is_a (that's what my error message says, which looks as following):


 File "c:\path\main.py", line 39, in <module>

    pset = ifcopenshell.util.element.get_psets(ifc.by_type("IfcMaterial"), psets_only=True)

  File "C:\Program Files\Python310\lib\site-packages\ifcopenshell\util\element.py", line 24, in get_psets

    if element.is_a("IfcTypeObject"):

AttributeError: 'list' object has no attribute 'is_a'

What I am trying to do is to get the correspondig psets of my materials to use in the api call described in your post (ifcopenshell.api.run("pset.edit_pset", ifc, pset=pset <- I'm looking for the pset to pass to the function here). If I access the materials with ifcopenshell.util.element.get_psets(ifc.by_type("IfcMaterial"), psets_only=True), I'm getting a list which is not the expected data type to pass as pset if I understand the error messages correctly.

If I keep iterating over the dictionary (as shown below), I keep getting an AttributeError since my dict object doesn't have an attribute called Name which is expected by the edit_pset method.


propertyname = "Test2"

for material in materials:

        psets = ifcopenshell.util.element.get_psets(material)

        for key, pset in psets.items():

                if propertyname in pset.keys():

                        ifcopenshell.api.run("pset.edit_pset", ifc, pset=pset, properties={"Test2": pset["Test1"]})

What is the correct way to query to actually get a data type which is compatible with the edit_pset method? I've tried to find a solution in this thread. There is a good example (coincidentally written by yourself as well) here which seems to work for psets of walls, however, I can't access the psets of my materials in the same way without ending up with an error message.

M by Moult on 29 Aug 2022 # +1 votes

ifc.by_type('IfcMaterial') returns a list of all materials in your project. You can get the psets of a single material by doing:


for material in ifc.by_type('IfcMaterial'):

    psets = ifcopenshell.util.element.get_psets(material)

get_psets returns a dictionary of psets, whereas the API expects an element. Each pset has an ID, which you can use to fetch the element.


        for key, pset in psets.items():

                if propertyname in pset.keys():

                        ifcopenshell.api.run("pset.edit_pset", ifc, pset=ifc.by_id(pset["id"]), properties={"Test2": pset["Test1"]})

Also of interest is the ifcopenshell.util.element.get_material(element) function :)

R by randomluck on 29 Aug 2022 # +1 votes

Thanks again @Moult - I've been awkward for some reasons. I didn't get right away that when looping over my pset keys, ifc.by_id(pset["id"] would already get the pset keys so I was trying a way more complicated solution by passing the id's by parsing them outside of the loop until I've noticed that I can leave it as is haha. The usual fun and "aha"-moments when digging into a new library :)

To wrap it up, this is what my solution looks like:



def modify_mat_pset(input, output, propertyname, newvalue):

        ifc = ifcopenshell.open(input)

        materials = ifc.by_type("IfcMaterial")



        for material in materials:

                psets = ifcopenshell.util.element.get_psets(material)

                for key, pset in psets.items():

                        if propertyname in pset.keys():

                                ifcopenshell.api.run(

                                        "pset.edit_pset", 

                                        file = ifc, 

                                        pset = ifc.by_id(pset["id"]), 

                                        properties = {propertyname:newvalue}

                                        )

        ifc.write(output)

The solution, however, is only good with prior knowledge of the property I want to change. It's also not (yet) considered that if there is a property set that shoulnd't be modified which however includes a property with the same name (since I'm querying for the propertyname (if propertyname in pset.keys()).

Thanks again and I'll take a look at the ifcopenshell.util.element.get_material(element)! :)

M by Moult on 29 Aug 2022 # +2 votes

Cheers, glad it works now :)

Z by Zanoni on 20 Mar 2024, edited 20 Mar 2024 #

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