Question

Django (and database) newbie here.

I’m trying to figure out a way to enable the creation of n custom text fields for a table (let’s call it Book) using the admin interface. I would like a way for the user to define new text fields through the admin interface (instead of defining fields like CustomField1, CustomField2, etc, through a model followed by running manage.py syncdb).

Ultimately, I would want to create a separate table called CustomFields. The django admin user (who is not a programmer), would go and enter the custom text fields in this table (e.g. pubdate, isbn, country). Then, when doing data entry for a Book, they would hit “+” for every custom field they wanted, have them available in a dropdown, and add accompanying text for the custom field. The text entered for each field is specific to the parent Book.

Any suggestions? I have a feeling there’s a simple solution that I’m somehow not grasping here.

Answer 1

Where you might run into problems is because Django will not recreate tables or columns based on changing model declarations. This means you’re unable to add fields to a table at run-time without running the generated sql on your database manually. What you’ll need, instead, is a way of defining custom fields, and linking them to your model.

What I’d suggest is the following:

class CustomField(models.Model):
    name = models.CharField(max_length=32)

class Book(models.Model):
    ... fields

class CustomValue(models.Model):
    field = models.ForeignKey(CustomField)
    value = models.CharField(max_length=255)
    book = models.ForeignKey(Book)

The validation on the above is fairly non-existant, and this doesn’t allow you to define required custom fields for each model, but you should be able to come up with that part if you need it later on.

# taken and modified from django online tutorial
class CustomValueInline(admin.StackedInline):
    model = CustomValue
    extra = 3

class BookAdmin(admin.ModelAdmin):
    fieldsets = [
       # your fields in here
    ]
    inlines = [CustomValueInline]

admin.site.register(Book, BookAdmin)

This will allow users to select up to 3 custom fields and values directly, with the option to add more if they wish.

Edit: Changed the answer to reflect further information in comments.