How to convert a foreign key field into many fields without breaking existing data in the database?

Question

My code snippet is as follows:

class Table1(models.Model):
    name = models.CharField(max_length=20)

class Table2(models.Model):
    name = models.CharField(max_length=20)
    description = models.TextField()
    table1 = models.ForeignKey(Table1)

Consider that the table has data in the database. What is a possible way to convert a field Foreign Key Field(in Table2)to Many To Manywithout losing existing data in the database?

*Note: I am using Django 1.6.4(not using Django migrations)*

Answer 1

You need to do this in a couple of steps. First add an M2M field and copy your data. Then change the application logic to use the new field. Finally, you can remove the old ForeignKey field.

Answer 2

class Table2(models.Model):
    name = models.CharField(max_length=20)
    description = models.TextField()
    table1 = models.ForeignKey(Table1)
    table1_new = models.ManyToManyField(Table1, related_name='_')

# python manage.py makemigrations && python manage.py migrate && python manage.py shell
# get things done by a for loop


class Table2(models.Model):
    name = models.CharField(max_length=20)
    description = models.TextField()
    table1_new = models.ManyToManyField(Table1, related_name='_')

# python manage.py makemigrations && python manage.py migrate


class Table2(models.Model):
    name = models.CharField(max_length=20)
    description = models.TextField()
    table1 = models.ManyToManyField(Table1)

# python manage.py makemigrations && python manage.py migrate