mirror of
https://github.com/qelectrotech/qelectrotech-source-mirror.git
synced 2026-09-28 13:24:14 +02:00
Beat Hangartner
2269a4641b
QETProject::m_uuid was created in the constructor and never written, so
a project got a new uuid every time it was opened. Inside a running
instance it is only used to name the SQLite connection, but nothing
outside the instance could tell which project a file belongs to.
Motivation
A .qet file is increasingly handled by tools outside QElectroTech: Git
repositories on GitHub or GitLab, cloud storage, key-value stores,
per-project locks. All of them need a stable key for "this project":
- The file name and path are not stable: files get renamed, moved,
checked out in different places.
- The project title is user-editable and not unique.
- Folio uuids (persisted separately) are only unique within their
project; keying folios globally needs a project identifier as well,
e.g. projects/{projectUuid}/folios/{folioUuid}.
Change
Write the uuid as an attribute of <project> and restore it in
QETProject::openFile(), right after parsing and before the project is
built from the XML. Older versions ignore the attribute, so files stay
readable in both directions.
The project database is not affected: it takes its connection name
from the uuid created at construction (m_uuid is declared before
m_data_base), before the file is read. Two open projects carrying the
same persisted uuid therefore still get distinct connections.
Files without a uuid: why not a random one
Keeping the random uuid created by the constructor and saving it
conflicts with #754 / #779: saving an unmodified project must give the
same bytes every time. Every example project predates the attribute.
Measured on the 24 example projects (resaved 3x each from the same
original, QT_HASH_SEED=0 so that QDom's attribute order is stable,
isolated HOME per run):
upstream master 23/24 byte-identical
persist, random uuid 0/24
persist, derived uuid (this) 23/24
The remaining project, schema_indus.qet, differs only in element uuids,
the known residual #779 leaves for elements; its project uuid is
stable.
Instead, a project file without a uuid gets a name-based (version 5)
uuid derived from the raw content of the file:
QUuid::createUuidV5(<fixed QET project namespace>,
"qet-project-legacy\n" + file content without CR)
- The same file always yields the same uuid, so resaving an unmodified
legacy project stays reproducible.
- Different projects practically never share a uuid, because any
difference in content gives a different one. This is unlike folios,
where only data such as title and position could be used; the raw
file bytes are stable input for the whole project.
- Carriage returns are dropped before hashing. QFile's Text mode already
strips them on Windows but not elsewhere, and git's autocrlf can
change them on checkout; either way the uuid is the same on every
platform.
- The uuid is derived once, at load time, and saved from then on. After
that it is read, never recomputed: renaming the project, editing it
or changing it in the same session as the migration does not change
it.
- Two people opening the same legacy file on different branches get the
same project uuid.
The namespace uuid is fixed in the code and must never change, or every
legacy project would get a different uuid.
Known limitations, open for discussion
- Copies share the uuid. Two byte-identical legacy files get the same
uuid (examples/cablage-eclairages_sikli-v5.qet and
câblage-éclairages-sikli-v5.qet are such a pair), and so does a
migrated file copied in the file manager or saved with "Save as".
That is what identity means for a copy, and the same happens with Git,
but a tool that treats the uuid as globally unique has to cope with
it. Regenerating the uuid on "Save as" could be a follow-up, if that
is the preferred behaviour.
- A legacy file that differs from another only in formatting (e.g.
re-indented) gets a different uuid. The two sides of a merge only
agree if they started from the same bytes, which is the normal case.
Tests (Qt 6.4, offscreen, qelectrotech --resave / --set-titleblock /
--info)
- 24 example projects, 3 resaves each from the same original: results
above; the project uuid is identical across runs. All 24 uuids are
distinct, except the byte-identical pair mentioned above.
- Resaving an already migrated file is byte-identical to the first
output.
- The same legacy file with CRLF line endings gets the same uuid as
with LF.
- Changing the project title in a migrated file keeps its uuid.
- Migrating and modifying in the same run (--set-titleblock on a legacy
file) gives the same uuid as a plain resave.
- Re-indenting a legacy file gives a different uuid (expected).
- A migrated file opened with upstream master loads normally; the
attribute is ignored and dropped on save.
- --info on a migrated file still works.
Refs #754, #779
Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01BDyt4txaott5JyPNGQaeVp