41 lines
1.1 KiB
Python
41 lines
1.1 KiB
Python
# Data migration: 从 Factory.short_name 的唯一值创建 Brand，并回填 Material.brand
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from django.db import migrations
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def forwards(apps, schema_editor):
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Factory = apps.get_model('factory', 'Factory')
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Brand = apps.get_model('brand', 'Brand')
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Material = apps.get_model('material', 'Material')
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short_names = (
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Factory.objects
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.exclude(short_name__isnull=True)
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.exclude(short_name='')
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.values_list('short_name', flat=True)
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.distinct()
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)
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for sn in short_names:
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Brand.objects.get_or_create(name=sn)
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for brand in Brand.objects.all():
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Material.objects.filter(factory__short_name=brand.name).update(brand=brand)
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def backwards(apps, schema_editor):
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# schema migration 回滚时会删掉 Material.brand 字段，这里无需操作
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pass
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class Migration(migrations.Migration):
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dependencies = [
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('material', '0007_add_brand_fk'),
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('factory', '0004_rename_brand_to_short_name'),
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('brand', '0001_initial'),
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]
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operations = [
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migrations.RunPython(forwards, backwards),
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]
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