Re: ManyToManyField is this right?

On 12-06-27 8:02 AM, David Wagner wrote:

Thanks for all the replies and I think I'm getting it now but it gets more complex too.

So NRA Licenses is essentialy going to become a type of several certifications. For instance.

NRA Instructor

• Home Firearm Safety Instructor
• Refuse to be a Victim Workshop
• and many more could be selected.....

CCL (or CCW in some states)

• State in Which your Certified (possibility of multiple states)

Many more different types of licenses and certifications are going to be added eventually so as you can see these relationships are going to get complex. So If I'm grasping this correctly let me try some code to see if I'm on the right track....

class NRA_Certs(models.Model):
    CRSO = models.BooleanField(blank=True, null=True, "Chief Range Safety Officer")
    HFS = models.BooleanField(blank=True, null=True, "Home Firearm Safety")
    MCR = models.BooleanField(blank=True, null=True, "Metallic Cartridge Reloading")
    PPH = models.BooleanField(blank=True, null=True, "Personal Protection in the Home")
    PPO = models.BooleanField(blank=True, null=True, "Personal Protection Outside the Home")
    PS = models.BooleanField(blank=True, null=True, "Pistol Shooting")
    RS = models.BooleanField(blank=True, null=True, "Rifle Shooting")
    SSR = models.BooleanField(blank=True, null=True, "Shotgun Shell Reloading")
    SS = models.BooleanField(blank=True, null=True, "Shotgun Shooting")
    RTBVDW = models.BooleanField(blank=True, null=True, "Refuse to be a Victim Workshop")
    RTBVO = models.BooleanField(blank=True, null=True, "Refuse to be a Victim Online")
    NMLRA_MP = models.BooleanField(blank=True, null=True, "NMLRA Muzzleloading Pistol Shooting")
    NMLRA_MR = models.BooleanField(blank=True, null=True, "NMLRA Muzzleloading Rifle Shooting")
    NMLRA_MS = models.BooleanField(blank=True, null=True, "NMLRA Muzzleloading Shotgun Shooting")

class NRA(models.Model):
    cert_type = models.ForeignKey(NRA_Certs)
    name = models.CharField() # Is this necessary? Can the name be set to text in the boolean fields from NRA_Certs?
    expiration = models.DateField(blank=True, null=True)

Does that look right or am I missing it completely. I'm not sure sure on the NRA_Certs all being boolean, my thinking is that whether they have that certification should be as simple as true/false.

Probably not. What happens if another new cert gets added to the the list? You will want a separate table entry for each kind of cert so when "Howitzer" gets added you can make that available without changing your models, only changing your data in the database.

afaict your new proposed class "NRA" does not add value here. Have certs, and have users. Should be enough.

You do have more than one piece of info for the cert model: an acronym and a long name or description. Those should be two fields in the model. Then use the many to many relation to allow multiple certs for each user and to allow multiple users to have the same cert.

hth

                - Tom


                 - Tom