33 lines
1.2 KiB
Python
33 lines
1.2 KiB
Python
from django.db import migrations, models
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from django.db.models import Min, Subquery
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def keep_earliest(apps, schema_editor):
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"""一人一题只保留最早的一条表情，多余的删掉。
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以前上限是 3 个，改成单选后这些老数据仍在给全站计数贡献数字。
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同一次提交的 create_time 相同，所以按自增 id 认「最早」。
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"""
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Reaction = apps.get_model("reaction", "Reaction")
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keep_ids = Reaction.objects.values("user_id", "problem_id").annotate(keep=Min("id")).values("keep")
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Reaction.objects.exclude(id__in=Subquery(keep_ids)).delete()
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class Migration(migrations.Migration):
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dependencies = [
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("reaction", "0002_delete_comment"),
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]
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operations = [
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# 删掉的数据回不来，回滚只当无事发生
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migrations.RunPython(keep_earliest, migrations.RunPython.noop),
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migrations.AlterUniqueTogether(
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name="reaction",
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unique_together=set(),
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),
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migrations.AddConstraint(
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model_name="reaction",
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constraint=models.UniqueConstraint(fields=("problem", "user"), name="reaction_problem_user_unique"),
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),
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]
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