Bad documentation of post_syncdb signal

[Vlastimil Zíma]

Signal post_sycndb is badly documented:

• documentation says that created_models is list, but emit_post_sync_signal is called with set when it is called from syncdb command. Surprisingly it is called with set from flush command, so there is probably error in code as well.
• documentation suggests that post_syncdb signal is called only when table is created, so it looks like you can use it to change database structure (create contraints, triggers, ...) These SQL fail when yout post_sycndb handler is called from flush, because flush does not change database structure (except SQLs with 'IF NOT EXISTS'-like conditions). Documentation should noted that handlers of this signal should not change database structure and for such cases customize sql hack in syncdb should be used.

[Vlastimil Zíma]

Bug in description: flush command calls emit_post_sync_signal with list of models as in documentation

[Ramiro Morales]

Seems to be a duplicate of #5848 -- but this ticket was opened on Mach 17 2011 against trunk and the other ticket was fixed on Sep 12 2010.

[Vlastimil Zíma]

Replying to ramiro:

Seems to be a duplicate of #5848 -- but this ticket was opened on Mach 17 2011 against trunk and the other ticket was fixed on Sep 12 2010.

I probably missed that, but the second point is still valid.

[Aymeric Augustin]

Regarding your second point, there's already a solution for this problem, see ​https://docs.djangoproject.com/en/dev/howto/initial-data/#providing-initial-sql-data

[Vlastimil Zíma]

Replying to aaugustin:

Regarding your second point, there's already a solution for this problem, see ​https://docs.djangoproject.com/en/dev/howto/initial-data/#providing-initial-sql-data

This does not work one would expected from documentation.

If I create initial SQL like

ALTER TABLE "some_table"
    ADD CONSTRAINT "some_table_constraint1" CHECK (some_column = 45);

This will make flush command fail, as it emits post_syncdb signal marking that table is created (but it is not). This can be sometimes prevented using IF NOT EXISTS condition, but not always.

[Justin Lilly]

​https://github.com/django/django/pull/43

[Preston Holmes]

applied - built docs, reads well

[Paul McMillan]

In [16874]:

Fixed #15633 -- Improved docs for post_syncdb signal.

[Paul McMillan]

In [16879]:

[1.3.X] Fixed #15633 -- Improved docs for post_syncdb signal. Thanks Justin Lilly for the patch.