Python Postgresql SQLAlchemy drop_all

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#Python #PostgreSQL

本文提供了一种解决方案来处理使用Python、PostgreSQL和SQLAlchemy时遇到的drop_all()失败问题，该问题由表之间的循环引用引起。通过自定义PGCascadeSchemaDropper类并覆盖visit_table方法，可以实现级联删除所有表。

Python + Postgresql + SQLAlchemy fix: drop_all() fails due to circular references

Posted by dandriff on Friday September 12, 2008@01:31PM

Here is the fix, as described by this helpful guy:

from sqlalchemy.databases import postgres

class PGCascadeSchemaDropper(postgres.PGSchemaDropper):
def visit_table(self, table):
for column in table.columns:
if column.default is not None:
self.traverse_single(column.default)
self.append("\nDROP TABLE " +
self.preparer.format_table(table) +
" CASCADE")
self.execute()

postgres.dialect.schemadropper = PGCascadeSchemaDropper