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I want my application to have default data such as user types.
What's the most efficient way to manage default data after migrations?
It needs to handle situations such as, after I add a new table, it adds the default data for it.
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By default, the configuration uses SQLite. If you're new to databases, or you're just interested in trying Django, this is the easiest choice. SQLite is included in Python, so you won't need to install anything else to support your database.
By default, Django adds an id field to each model, which is used as the primary key for that model. You can create your own primary key field by adding the keyword arg primary_key=True to a field. If you add your own primary key field, the automatic one will not be added.
The __str__ method just tells Django what to print when it needs to print out an instance of the any model. It is also what lets your admin panel, go from this. Note: how objects are just plainly numbered. to this.
When you make a model class in Django, consider that class the data-table, each individual instance of that class the table rows, and the attributes(e.g: title) of each table the columns. In the definition of the class Book, title seems to be a class attribute.
You need to create an empty migration file and Do your stuff in operations block, as explained in docs.
Data Migrations
As well as changing the database schema, you can also use migrations to change the data in the database itself, in conjunction with the schema if you want.
Now, all you need to do is create a new function and have RunPython use it
Docs explains this with an example to show ,how to communicate with your models.
From Docs
To create an empty migration file,
python manage.py makemigrations --empty yourappname And this is the example how to update a newly added field.
# -*- coding: utf-8 -*- from __future__ import unicode_literals from django.db import migrations, models def combine_names(apps, schema_editor): # We can't import the Person model directly as it may be a newer # version than this migration expects. We use the historical version. Person = apps.get_model("yourappname", "Person") for person in Person.objects.all(): person.name = "%s %s" % (person.first_name, person.last_name) person.save() class Migration(migrations.Migration): initial = True dependencies = [ ('yourappname', '0001_initial'), ] operations = [ migrations.RunPython(combine_names), ] If you love us? You can donate to us via Paypal or buy me a coffee so we can maintain and grow! Thank you!
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