BathAfrica: Publish rewritten step-by-step OpenSite lesson with checked results

2026-10-29T20:58:54Z

Publish rewritten step-by-step OpenSite lesson with checked results

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__NOTOC__
{{OpenSite scope}}
{{OpenSite lesson
|id=opensite.help.first-document
|summary=Create a small rectangular-section document, change one dimension, undo and redo, then save and reopen it.
|prerequisites=A matching OpenSite development build. Run the complete example with the explicit development host because <code>document.create_section</code> uses <code>document.edit</code>. Use a practice document, not a live project.
|steps==== Create the practice section ===
The example starts at 250 mm wide and 500 mm high. The stored lengths are 0.25 m and 0.50 m. This rectangle is a document-engine example, not a section-design or FEM workflow.
[[File:OpenSite_Rectangle_Lesson.svg|720px|center]]

=== Change width and inspect the result ===
Change width to 300 mm using <code>document.set_quantity</code>. The height remains 500 mm and area changes from 0.125 to 0.15 m². Derived values are recomputed by the transaction.

=== Undo and redo ===
Undo restores the 250 mm width. Redo reapplies 300 mm. Compare values after each operation instead of relying on a visual redraw.

=== Save to a new location and reopen ===
The complete example creates a fresh temporary folder, prints its path, saves an <code>.osdoc</code> and opens it again. The filename extension is conventional; the writer format is version 4. Undo history is not stored.

|result=Area is 0.125 m² initially and 0.15 m² after the edit; undo restores width 0.25 m. The saved document reopens with area 0.15 m².
|limitations=This teaches document transactions and persistence. It does not validate a structural member or perform a design-code check.
}}

== Complete example ==
{{Code|lang=python|code=<nowiki>from pathlib import Path
from tempfile import mkdtemp
import opensite

created = opensite.execute("document.create_section", {
"label": "PracticeBeam",
"width": opensite.QuantityArgument(opensite.Q("250 mm"), "mm"),
"height": opensite.QuantityArgument(opensite.Q("500 mm"), "mm"),
})
doc, beam_id = created["document"], created["object"]
assert abs(doc.property(beam_id, "area").si_value - 0.125) < 1e-12

opensite.execute("document.set_quantity", {
"document": doc, "object": beam_id, "property": "width",
"value": opensite.QuantityArgument(opensite.Q("300 mm"), "mm"),
})
assert abs(doc.property(beam_id, "area").si_value - 0.15) < 1e-12
opensite.execute("document.undo", {"document": doc})
assert abs(doc.property(beam_id, "width").si_value - 0.25) < 1e-12
opensite.execute("document.redo", {"document": doc})

path = Path(mkdtemp(prefix="opensite-lesson-")) / "practice-beam.osdoc"
opensite.execute("document.save", {"document": doc, "path": str(path)})
reopened = opensite.execute("document.open", {"path": str(path)})["document"]
assert abs(reopened.property(beam_id, "area").si_value - 0.15) < 1e-12
print("Saved and reopened:", path)</nowiki>}}

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[[Category:OpenSite documentation]]

OpenSite/Guides/First document - Revision history

BathAfrica: Publish rewritten step-by-step OpenSite lesson with checked results