Question

I m using Django (specifically django-admin) to be the admin panel for a site that uses PHP for client-facing features. I ve been messing around making the admin look exactly the way I want and so far so good. However, I ve run into a few problems that I need solving.

Here s the models that I m working with:

class Permissions(models.Model):
    id = models.IntegerField(primary_key=True)
    league_key = models.CharField(max_length=15) 
    commissioner_id = models.ForeignKey(Accounts, db_column= commissioner_id ,
                                        to_field= id )
    status = models.IntegerField()
    key = models.CharField(max_length=50)
    publisher_key = models.CharField(max_length=25)
    publisher_display_name = models.CharField(max_length=50)
    base_league = models.ForeignKey( self , db_column= id )
    share = models.IntegerField()
    default_fixture_key = models.CharField(max_length=50)

    def __unicode__(self):
        return self.publisher_key +   /   + self.league_key

    class Meta:
        db_table = u permissions 
        verbose_name =  Permissions 
        verbose_name_plural =  Permissions 

class PermissionsAdmin(admin.ModelAdmin):
    list_display = ( league_key ,  publisher_key ,  commissioner_id ,  status ,
                     base_league ,  share ,  default_fixture_key )
    list_display_links = ( league_key , commissioner_id ,  base_league )
    exclude = ( id ,)

First problem is that the admin form for editing an existing record is marking one of the fields as required. How do I tell the django-admin when a field is required and not required?

Second problem I am running into is that when I tell it to Save this record, I get the following error: duplicate key value violates unique constraint "permissions_pkey". That leads me to think that Django is not doing an update, it s trying to do an INSERT

It also occurred to me that this might be a problem related to Postgresql. permissions_pkey is a constraint on that table, keeping track of the sequence being used for auto-incrementing the id for that table

While the Django docs are awesome, they don t seem to have the info I need to figure this out.

(EDIT: Digging into the stack trace, I found this awesome little nugget:

sql 
 UPDATE "permissions" SET "league_key" = E l.1258472565  , "commissioner_id" = 7,
 "status" = 0, "key" = E cfcd208495d565ef66e7dff9f98764da  , 
"publisher_key" =     E chrishartjes.com  , 
"publisher_display_name" = E Chris Hartjes Free Press  , 
"id" = 744, "share" = 0, 
"default_fixture_key" = E   WHERE "permissions"."id" = 745

which leads me to think that my little ForeignKey to itself entry is causing the problem)

Answer 1

Problem 1: See the documentation on setting null and blank. Short story: setting null will allow the DB to store a null value. What you want here (most likely) is to set blank to True so that when it validates the model that field won t be required. If the field isn t a CharField, you should also set null to True. See the docs here: http://docs.djangoproject.com/en/dev/ref/models/fields/#field-options

Problem 2: I believe that what you want here is an AutoField, not an IntegerField. The difference is just that an AutoField will create a new id for you automatically when saving a new object. See the docs here: http://docs.djangoproject.com/en/dev/ref/models/fields/#autofield

Edit: (from my comment) Looking again I see that the error references permissions_pkey. Try replacing the id field with pkey = AutoField(primary_key=True).

Answer 2

On the field, put null=True in the field constructor if the field is not required. Edit: commenter says blank=True -- he s probably right -- I don t have the docs in front of me.
It does an insert if the ID is empty and an update if the id has a value. Not sure where the save you are talking about is happening, but that info might help. (there s a deleted answer that points out that the exclude( id ) is probably causing this problem -- I think that s right as well)

Also, I agree about the docs. If you can read python, I highly suggest just trying to read the Django source code for the area you want to figure out. The source is some of the nicest, most readable source I ve ever read. I ve never had a problem just jumping in and reading it -- it s almost as good as a doc.

Answer 3

null=True, blank=True
You don t need to explicitly have the "id" column in your Permissions model, I believe that s what s causing your second problem.

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