makemigration - 创建模型并只插入一次数据

Question

我有一个模型如下：

from django.db import models

class Country(models.Model):
    cid = models.SmallAutoField(primary_key=True)
    label = models.CharField(max_length=100)
    abbr = models.CharField(max_length=3)

countries = {
"AFG": "Afghanistan",
"ALB": "Albania",
"DZA": "Algeria",
"ASM": "American Samoa",
"AND": "Andorra",
"AGO": "Angola",
"AIA": "Anguilla"
};


for c in countries:
    row = Country(label = countries[c], abbr = c)
    row.save()

现在每当我运行以下命令时：

python manage.py makemigrations

第一次，它创建表并填充它。第 2 次、第 3 次等等，一直插入相同的数据（我肯定会多次使用 makemigration 命令，所以我不希望它每次运行命令时都插入它）

有什么方法可以做到这一点？创建并插入一次？

Answer 1

您可以添加创建数据的data migrations，这些会在应用迁移时运行一次。这是一个示例，您的数据迁移被添加到同时添加模型的迁移中

from django.db import migrations, models

countries = {
    "AFG": "Afghanistan",
    "ALB": "Albania",
    "DZA": "Algeria",
    "ASM": "American Samoa",
    "AND": "Andorra",
    "AGO": "Angola",
    "AIA": "Anguilla"
}


def create_countries(apps, schema_editor):
    Country = apps.get_model('myapp', 'Country')
    for c in countries:
        Country.objects.create(label=countries[c], abbr=c)


class Migration(migrations.Migration):

    dependencies = [
        ('myapp', '0000_previous'),
    ]

    operations = [
        migrations.CreateModel(
            name='Country',
            fields=[
                ('cid', models.SmallAutoField(primary_key=True, serialize=False)),
                ('label', models.CharField(max_length=100)),
                ('abbr', models.CharField(max_length=3)),
            ],
        ),
        migrations.RunPython(create_countries),
    ]