Thank you very much Simone and Michal for your timely response. I made all
the fields those are part of primary keys as unique and added a dummy
auto-increment ID for these tables and did migrations.
So far so good.
Thanks,
Ramesh.
On Tuesday, January 3, 2017 at 5:35:07 PM UTC+5:30, ramesh wrote:
>
> Hi,
>
> Below is the model generated for one of the table from the legacy database
> using "inspectdb"
>
> class Test(models.Model):
> field1 = models.AutoField(db_column='Field1') # Field name made
> lowercase.
> field2 = models.ForeignKey('Field2', models.DO_NOTHING,
> db_column='Field2') # Field name made lowercase.
> field3 = models.CharField(db_column='Field3', max_length=200) # Field
> name made lowercase.
> field4 = models.CharField(db_column='Field4', max_length=300,
> blank=True, null=True) # Field name made lowercase.
>
> class Meta:
> managed = False
> db_table = 'test'
> unique_together = (('field1', 'field2'),)
>
>
> Table definition in MySQL:
> CREATE TABLE comment (
> Field1 INT UNSIGNED NOT
> NULL AUTO_INCREMENT COMMENT 'Field1',
> Field2 INT UNSIGNED NOT
> NULL COMMENT 'Field2',
> Field3 VARCHAR(200) NOT
> NULL COMMENT 'Field3',
> Field4
> VARCHAR(300) DEFAULT NULL COMMENT
> 'Field4',
> KEY ( Field2 ),
> FOREIGN KEY (Field2) REFERENCES item (Field2) ON DELETE CASCADE,
> PRIMARY KEY ( Field1, Field2 )
> ) ENGINE=InnoDB DEFAULT CHARSET=utf8;
>
> Migrations failed with the error,
> "A model can't have more than one AutoField."
> AssertionError: A model can't have more than one AutoField.
>
> Tried work around of
>
> from compositekey import db
>
> id = db.MultiFieldPK("field1", "field2")
>
>
> Now a different error,
>
> from django.db.models.sql.aggregates import Aggregate
> ImportError: No module named aggregates
>
>
> Another work around of defining a new auto_increment field as primary key
> but here one of the composite keys (field1) is auto_incremental causing 2
> auto_increment fields in a table.
>
> Also this needs MySQL table alter, as this is a legacy database with many
> tables, this is quite difficult.
>
> Please advise me on work around, correct me if I am missing some thing
> here in the process.
>
> Thanks in advance.
>
> Ramesh.
>
>
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