BathAfrica: Add rewritten practical lesson with steps, code and expected results

2026-10-29T21:00:59Z

Add rewritten practical lesson with steps, code and expected results

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__NOTOC__
{{OpenSite scope}}
{{OpenSite lesson
|id=opensite.help.exchange-materials
|summary=Export a material set and import it into another document.
|prerequisites=Two practice documents and the material API. This lesson uses an in-memory exchange string rather than overwriting a file.
|steps==== Build the source material set ===
Create a user-defined material with explicit SI inputs.

=== Export and identify the format ===
<code>material_export</code> returns text containing <code>opensite-material-exchange</code>. This is a material exchange payload, not the full <code>opensite-document</code> file.

=== Import into a fresh document ===
Pass the exported text to <code>material_import</code> with the destination handle.

=== Verify the imported properties ===
List the destination materials and read the imported object’s elastic modulus. Check values, not equality of source/destination object IDs.

|result=The destination has one material and its elastic modulus is 210 GPa.
|limitations=Exchange does not copy geometry, undo history or the entire model. Do not assume identity values or numbering are portable between documents.
}}

== Complete example ==
{{Code|lang=python|code=<nowiki>import opensite

source = opensite.execute("document.new", {})["document"]
values = {
"name": "Practice steel", "family": "steel", "role": "structural_steel",
"has_elastic": True, "elastic_pa": 210.0e9,
"has_poisson": True, "poisson": 0.28,
"has_mass_density": True, "mass_density": 7850.0,
"has_thermal": True, "thermal_per_k": 1.2e-5,
}
opensite.material_create_user(source, values)
payload = opensite.material_export(source)["text"]
assert "opensite-material-exchange" in payload
destination = opensite.execute("document.new", {})["document"]
opensite.material_import(destination, payload)
rows = opensite.material_list(destination)
assert len(rows) == 1
item = destination.get_object(rows[0]["id"])
assert abs(item.elastic_modulus.si_value - 210e9) < 1.0
print("Imported materials:", len(rows))
# This is a material exchange, not a copy of the whole source document.</nowiki>}}

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BathAfrica: Add rewritten practical lesson with steps, code and expected results