IfcOpenShell, how to add a new property and value to an object?

FDinis

Hey guys, I'm pretty new to IfcOpenShell.
What I'm trying to achieve is to iterate through a dictionary of attributes (keys) and their corresponding values and add them to an existing object.
I know I can access an object's attributes using something like:
wall.Name
or even change the Name to something that I want:
wall.Name = 'some value'
However, I don't want to have to type the name of the attribute since I'm iterating through a dictionary of attribute names and values.
Additionally, I know it is possible to change the values inside the someobject.get_info(), although that does not update the real object's attributes.
If I try to print the object, it still has the "original" set of attributes:
print(str(someobject))
Something like:
currentObject.my_custom_attributeName = my_custom_attributeValue
does not work.
How can I achieve this?
Thank you!

Coen

What about assigning a propertyset with Python IfOpenShell?

# Create and assign property set
import ifcopenshell 
ifc_file = 'path\to_your\ifc_file'
ifcfile = ifcopenshell.open(ifc_file)
products = ifcfile.by_type("IfcProduct")
owner_history = ifcfile.by_type("IfcOwnerHistory")[0]

walls=[]
for i in products:
    if i.is_a("IfcWall"):
        walls.append(i) 

property_values = [
    ifcfile.createIfcPropertySingleValue("Some Property Set Name ", "Some Property  Name", ifcfile.create_entity("IfcText", "Some Value"), None),
]   
for wall in walls:
    property_set = ifcfile.createIfcPropertySet(wall.GlobalId, owner_history, "Some Property Set Name ", None, property_values)
    ifcfile.createIfcRelDefinesByProperties(wall.GlobalId, owner_history, None, None, [wall], property_set)

ifcfile.write(ifc_file)  

Coen

I just tested this little script on a simple IfcWall,

IFC file after running this script.

Moult

In IFC, attributes are fixed. If you want to add arbitrary properties, use property sets, not attributes. This is as @Coen has explained. However, there is a simpler method using the IfcOpenShell API.

import ifcopenshell
import ifcopenshell.api
ifc = ifcopenshell.open('path\to_your\ifc_file')
element = ifc.by_type("IfcElement")[0] # Just as an example, you will need to select the elements you want to add properties to yourself.
pset = ifcopenshell.api.run("pset.add_pset", ifc, product=element, name="Your Property Set Name")
ifcopenshell.api.run("pset.edit_pset", ifc, pset=pset, properties={"foo": "foobar", "foo2": "foobaz"})

Coen

@Moult
Maybe it's convenient to mention how to install the ifcopenshell.api as you described here.

FDinis

Thanks for your answers @Moult and @Coen!
But what should I do in case I need to change the actual attributes of an object? I mean, I know I can type wall.Name = "Some other name", or wall.OwnerHistory = "some new value", etc. However, if I have a dictionary with a set of keys (attribute names that already exist on target object) and values (attribute values that I want to change on target object), what should I do?
It should be something like:
1. Select target object given an ID
2. Iterate through a given dictionary and then change the values of target object's attributes

Do you have any advice?
Thank you once again.

Moult

@Coen indeed thanks.

@FDinis once you have the pset element, use ifcopenshell.api.run("pset.edit_pset", ifc, pset=pset, properties={"foo": "foobar", "foo2": "foobaz"}). It will take care of editing it.

FDinis

@Moult
Thank you! :)

bernd

great code examples.

@Moult said:
In IFC, attributes are fixed. If you want to add arbitrary properties, use property sets, not attributes. This is as @Coen has explained. However, there is a simpler method using the IfcOpenShell API.

import ifcopenshell
import ifcopenshell.api
ifc = ifcopenshell.open('path\to_your\ifc_file')
element = ifc.by_type("IfcElement")[0] # Just as an example, you will need to select the elements you want to add properties to yourself.
pset = ifcopenshell.api.run("pset.add_pset", ifc, product=element, name="Your Property Set Name")
ifcopenshell.api.run("pset.edit_pset", ifc, pset=pset, properties={"foo": "foobar", "foo2": "foobaz"})

asumed I do not want to add a new pset but edit a property from a existing pset. What is a simple method to retrieve the pset entities what works with IFC2x3? ifcopenshell.util.element.get_psets(e) returns the contents but not the entity.

cheers bernd

vpajic

@bernd - Do you want to edit a single occurrence of a property, aka for a single object, or are you trying to edit all instances of a certain property?

Moult

@bernd the latest IfcOpenShell util module has a fix for exactly this purpose, ifcopenshell.util.element.get_psets(e) will now return an id for each pset so you can easily grab it for editing.

bernd

@Moult said:
@bernd the latest IfcOpenShell util module has a fix for exactly this purpose, ifcopenshell.util.element.get_psets(e) will now return an id for each pset so you can easily grab it for editing.

means I need to use 0.7.0 ?

bernd

@vpajic said:
@bernd - Do you want to edit a single occurrence of a property, aka for a single object, or are you trying to edit all instances of a certain property?

both, but for the latter I just iterate over all single ones

Moult

@bernd you don't need to, the util module is Python only so you can just grab the latest Python files from there.

bernd

@Moult said:
@bernd you don't need to, the util module is Python only so you can just grab the latest Python files from there.

ahh sure that would work too.

I upgraded to 0.70 anyway ...

BTW: works great with this is it is much simpler to get the pset.

cheers bernd

bernd

It does not work to access a changed property. Still the old value is used before the edit. Is there a way this is possible without writing and rereading the IFC file?

As a workaround I do save the properties in separate dicts, but this gets complicated as more properties are involved or if a property is for some reason changed twice.

cheers bernd

Moult

@bernd I don't understand. You don't need to write (serialise) and re-read the IFC file.

import ifcopenshell
import ifcopenshell.api
import ifcopenshell.util.element
ifc = ifcopenshell.api.run("project.create_file")
element = ifc.createIfcWall()
pset = ifcopenshell.api.run("pset.add_pset", ifc, product=element, name="Pset_Name")
ifcopenshell.api.run("pset.edit_pset", ifc, pset=pset, properties={"foo": "foobar", "foo2": "foobaz"})
psets = ifcopenshell.util.element.get_psets(element)
ifcopenshell.api.run("pset.edit_pset", ifc, pset=ifc.by_id(psets["Pset_Name"]["id"]), properties={"foo": "changed"})
print(ifcopenshell.util.element.get_psets(element))

bernd

ok works great here ...

BTW: related in the regard of property types ... https://github.com/IfcOpenShell/IfcOpenShell/issues/1889

vpajic

@bernd have you tested dions commit related to this issue?

bernd

NO not yet, ATM I do not need to change the property type, but I wanted to save the link in case it is needed.
ATM I only change property values, but I make heavy usage of this :-) works great so far.

shanmama

By observing the problems with IfcOpenShell in recent months, in fact, I think that only one "tool" can solve more than 90% of related problems: a complete documentation. Link: https://pythonhosted.org/eppy/Main_Tutorial.html
I came across a Python plug-in for parsing idf files, called eppy, on Sunday. I read the documentation on Monday morning and completed the development of a computing plug-in in the afternoon. There are detailed calculation examples, code examples, and even clear explanations of some algorithms and data structures in the documentation of eppy.

Obviously IfcOpenShell does not have such a clear documentation, many functions are "fuzzy" for beginners, and the calculation examples are not very abundant.

I hope that enthusiastic researchers can refer to the documentation of eppy to write a documentation of IfcOpenShell. This can be more friendly to beginners