更新笔记于 2023-12-08_16:48:45

python/python可变对象在sqlalchemy中的问题.md

@@ -0,0 +1,72 @@
+# python可变对象在sqlalchemy中的问题
+
+
+## 问题
+sqlalchemy 在处理可变对象时，如果可变对象地址没有变化，不会触发更新
+
+
+```python
+
+repo = session_maker
+
+async def test_edit_fields(
+    self, engine,init_app_page_extractions
+):
+    repo = container.repo()
+    async with repo.new_session() as session, session.begin():
+        result = await repo.session.execute(select(PageCommandOrm))
+        pages = result.scalars().all()
+        for row in pages:
+            print(row.edit_fields)
+            row.edit_fields["ff"] = 1
+
+
+        repo.session.add_all(pages)
+
+    async with repo.new_session() as session, session.begin():
+        session.flush()
+        result = await repo.session.execute(select(PageCommandOrm))
+        pages = result.scalars().all()
+        for row in pages:
+            print(row.edit_fields)
+
+```
+
+输出如下
+```
+{}
+{}
+{}
+{}
+{}
+{}
+```
+
+在上面的例子中，`row.edit_fields["ff"] = 1` 这样的操作不会修改edit_fields 这个变量的地址，因此sqlalchemy认为未修改该字段，不会更新该字段
+
+而`row.edit_fields = {"ff":1}` 修改了，触发了更新
+
+
+## 解决方案
+
+使用官方提供的方法`flag_modified`
+
+```
+from sqlalchemy.orm.attributes import flag_modified
+
+async def test_edit_fields(
+    self, engine, init_app_page_extractions
+):
+    
+    repo = container.repo()
+    async with repo.new_session() as session, session.begin():
+        result = await repo.session.execute(select(PageCommandOrm))
+        pages = result.scalars().all()
+        for row in pages:
+            print(row.edit_fields)
+            row.edit_fields["ff"] = 1
+            flag_modified(row, "edit_fields") # 标记该字段需更新
+           
+
+        repo.session.add_all(pages)
+```

python/vx.json

@@ -160,6 +160,16 @@
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+            "created_time": "2023-12-08T07:18:13Z",
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+            "modified_time": "2023-12-08T08:48:35Z",
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