DXF Content

General preconditions:

import ezdxf
doc = ezdxf.readfile("your_dxf_file.dxf")
msp = doc.modelspace()

Get/Set Block Reference Attributes

Block references (Insert) can have attached attributes (Attrib), these are simple text annotations with an associated tag appended to the block reference.

Iterate over all appended attributes:

# get all INSERT entities with entity.dxf.name == "Part12"
blockrefs = msp.query('INSERT[name=="Part12"]')
if len(blockrefs):
    entity = blockrefs[0]  # process first entity found
    for attrib in entity.attribs:
        if attrib.dxf.tag == "diameter":  # identify attribute by tag
            attrib.dxf.text = "17mm"  # change attribute content

Get attribute by tag:

diameter = entity.get_attrib('diameter')
if diameter is not None:
    diameter.dxf.text = "17mm"

Adding XDATA to Entities

Adding XDATA as list of tuples (group code, value) by set_xdata(), overwrites data if already present:

doc.appids.new('YOUR_APPID')  # IMPORTANT: create an APP ID entry

circle = msp.add_circle((10, 10), 100)
circle.set_xdata(
    'YOUR_APPID',
    [
        (1000, 'your_web_link.org'),
        (1002, '{'),
        (1000, 'some text'),
        (1002, '{'),
        (1071, 1),
        (1002, '}'),
        (1002, '}')
    ])

For group code meaning see DXF reference section DXF Group Codes in Numerical Order Reference, valid group codes are in the range 1000 - 1071.

Method get_xdata() returns the extended data for an entity as Tags object.

Get Overridden DIMSTYLE Values from DIMENSION

In general the Dimension styling and config attributes are stored in the Dimstyle entity, but every attribute can be overridden for each DIMENSION entity individually, get overwritten values by the DimstyleOverride object as shown in the following example:

for dimension in msp.query('DIMENSION'):
    dimstyle_override = dimension.override()  # requires v0.12
    dimtol = dimstyle_override['dimtol']
    if dimtol:
        print(f'{str(dimension)} has tolerance values:')
        dimtp = dimstyle_override['dimtp']
        dimtm = dimstyle_override['dimtm']
        print(f'Upper tolerance: {dimtp}')
        print(f'Lower tolerance: {dimtm}')

The DimstyleOverride object returns the value of the underlying DIMSTYLE objects if the value in DIMENSION was not overwritten, or None if the value was neither defined in DIMSTYLE nor in DIMENSION.

Override DIMSTYLE Values for DIMENSION

Same as above, the DimstyleOverride object supports also overriding DIMSTYLE values. But just overriding this values have no effect on the graphical representation of the DIMENSION entity, because CAD applications just show the associated anonymous block which contains the graphical representation on the DIMENSION entity as simple DXF entities. Call the render method of the DimstyleOverride object to recreate this graphical representation by ezdxf, but ezdxf does not support all DIMENSION types and DIMVARS yet, and results will differ from AutoCAD or BricsCAD renderings.

dimstyle_override = dimension.override()
dimstyle_override.set_tolerance(0.1)

# delete associated geometry block
del doc.blocks[dimension.dxf.geometry]

# recreate geometry block
dimstyle_override.render()