Adding custom fields to a django model (without changes in source code)

You can create a table that follows the EAV principle (Entity Attribute Value). Basically this is a denormalised table with following columns:
[ID (and/or slug), float_value, integer_value, string_value] (Add more columns to this table)

Now say you've a existing table called "Member". When customer adds a dynamic field via your UI, you add the entries here and use "ID" to look them up for a given member.

I use Django Dynamic Forms. Out of the box, it lets users create their own forms through the admin. You might want to extend it to build a more user-friendly UI, but this should get you pretty far. It supports

• boolean
• choices (select)
• multiple choices (multiple select)
• date
• datetime
• time
• email
• integer
• single line text
• multi line text

Well, when I had such problem, I used to create a custom field model, with a name field and a type field, usually a choice field with choices for the possible field types. You can also add a is_active field to filter the active and inactive CustomFields.

Than, when I create the for, I search this objects to know which fields I must have in that form.

To store the data, I'd have another model, called CustomFieldAnswer, or somethink like this. This model should have a ForeignKey to the main model that should have this data, and the custom field.

Doing so, You can have any kinds of fields for yout model dinamically and wothout you client needing to code anything.

You could use metaprogramming to create acutual fields in a form based on the query in the CustomFields. Or, you could just put the fields in the template and change the type of the input for each CustomField.

Hope that helps!

If that's really what you want.

1. Create enough fields that your customer ever need.

   boolean_field_1 = models.BooleanField(..)
   boolean_field_2 ..
   date_field_1 = ..
   date_field_2 = ..
   

2. Store alias mapping somewhere.

   I could add a field for alias mapping.

   json_mapping_field = JSONField()
   # this has is_successful: boolean_field_1
   

3. Then find places where you can substitute the alias back to the real field name

   for simple filter and update, you could override

   1. QuerySet.filter Queryset.exclude
   2. QuerySet.update, UpdateQuery.add_update_values
   3. finally use from_queryset for your manager to use the overidden QuerySet.

I know it sounds like an awful hack, but maybe you can build an interface that creates text files?

1. One file would be models.py, with model definitions, and excluding this model from migrations with managed = False
2. Another file is the SQL with DROP and CREATE table if the customer wants a new table, or just ALTER table.
3. Another script can run the SQL script, copy the models.py file to the correct directory, and reload django.

I just discovered, that there is even a comparison grid on djangopackages about this:

https://www.djangopackages.com/grids/g/dynamic-models/

Heading:

Apps to add fields to models in the settings, or even at runtime.

Some StackOverflow administrator deleted this answer, that's why I write it again.

Reason of deletion was:

While this link may answer the question, it is better to include the essential parts of the answer here and provide the link for reference. Link-only answers can become invalid if the linked page changes.

Here are the current packages which are listed on the comparison grid today:

• django-mutant
• eav-django
• django-dynamic-model
• django-dynamo