I am fairly new to Django and I think I pretty much get the basic idea
of ORM. However, there is a peculiar situation to which I do not see a
plausible solution. I have a legacy database for which I am trying to
write a Django app. The sql structure of both the tables is:
mysql> describe event;
+-----------+------------------+------+-----+---------+-------+
| Field | Type | Null | Key | Default | Extra |
+-----------+------------------+------+-----+---------+-------+
| sid | int(10) unsigned | NO | PRI | NULL | |
| cid | int(10) unsigned | NO | PRI | NULL | |
| signature | int(10) unsigned | NO | MUL | NULL | |
| timestamp | datetime | NO | MUL | NULL | |
+-----------+------------------+------+-----+---------+-------+
mysql> describe alerts;
+----------------+-----------+------+-----+-------------------
+----------------+
| Field | Type | Null | Key | Default |
Extra |
+----------------+-----------+------+-----+-------------------
+----------------+
| id | int(11) | NO | PRI | NULL |
auto_increment |
| sid | int(11) | YES | MUL | NULL
| |
| cid | int(11) | YES | | NULL
| |
| confidence | int(11) | YES | | NULL
| |
| cvss_base | float | YES | | NULL
| |
| composite_conf | float | YES | | NULL
| |
+----------------+-----------+------+-----+-------------------
+----------------+
The first table cannot be altered because it would break a lot of code
(which I have not written). The second table was written by me (hence
the surrogate key).In the second ('alerts') table, (sid,cid) is
unique.
The problem is that (sid,cid) is the key on which tables can be
effectively joined. How should the models be re-written so that Django
can accurately capture the relation between the two tables? I tried
OnetoOne for both sid and cid separately but that is clearly not
useful since OnetoOne should apply on (sid,cid) simultaneously.
OnetoMany is also of no use and neither is ForeignKey since I need
(sid,cid) to be the foreign key.
It appears that (sid,cid) composite field should be OnetoOne but I
don't know how to achieve that.
Note - (sid,cid) value will be of the type
1-55,2-55,3-55,1-56,2-57,3-60 etc. all of which are unique and will
have only one entry in both the tables.
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