如何动态创建 SQLAlchemy 列
我有一个 csv 文件,第一行作为字段,其余行作为数据。我想用这个文件创建一个表。由于字段很长并且可能会有所不同,因此我想动态创建它。 经过几次尝试和搜索,我想我也许可以从工厂生成一个类,然后将属性分配给新类可以生成动态列。但它失败了。根据这个错误,我尝试了一些其他方法,但都失败了。请帮忙。我正在考虑这样的想法是否可行。
Reader = csv.reader(open('Book1.csv', 'rb'), delimiter=',', quotechar='|')
TableItem = Reader.next()[0:]
def Factory(*args, **kwargs):
args=args[0]
def init(self, *iargs, **ikwargs):
#setattr(self,__tablename__,ikwargs[__tablename__])
for k,v in kwargs.items():
setattr(self, k, v)
for i in range(len(iargs)):
setattr(self, args[i], iargs[i])
for k,v in ikwargs.items():
setattr(self, k, v)
name = kwargs.pop("name", "myFactory")
kwargs.update(dict((k, None) for k in args))
return type(name, (object,), {'__init__': init})
LIS=Factory(TableItem)
class newLIS(LIS,Base):
__tablename__='testonly'
pass
mytest=[]
for row in Reader:
mytest.append(newLIS(row))
错误是这样的:
sqlalchemy.exc.ArgumentError: Mapper Mapper|newLIS|testonly could not assemble
any primary key columns for mapped table 'testonly'
I have a csv file with first line as fields and remaining lines as data. With this file I would like to create a table. Since the fields are quite long and may vary, I want to dynamically create it.
After several tries and searches, I figured I could maybe generate a Class from factory and then assign the attributes to the new class could generate dynamic columns. But it fails. And based on the error, I tried some other methods, all failed. Please help. I'm considering whether it's doable for such an idea.
Reader = csv.reader(open('Book1.csv', 'rb'), delimiter=',', quotechar='|')
TableItem = Reader.next()[0:]
def Factory(*args, **kwargs):
args=args[0]
def init(self, *iargs, **ikwargs):
#setattr(self,__tablename__,ikwargs[__tablename__])
for k,v in kwargs.items():
setattr(self, k, v)
for i in range(len(iargs)):
setattr(self, args[i], iargs[i])
for k,v in ikwargs.items():
setattr(self, k, v)
name = kwargs.pop("name", "myFactory")
kwargs.update(dict((k, None) for k in args))
return type(name, (object,), {'__init__': init})
LIS=Factory(TableItem)
class newLIS(LIS,Base):
__tablename__='testonly'
pass
mytest=[]
for row in Reader:
mytest.append(newLIS(row))
The error is like:
sqlalchemy.exc.ArgumentError: Mapper Mapper|newLIS|testonly could not assemble
any primary key columns for mapped table 'testonly'
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我是相关答案的作者:
sqlalchemy 动态映射
我有这个答案另一个问题,我认为更相关 - 它甚至可能是重复的:
使用脚本语言的动态数据库
如您所见,要创建它,您需要创建一个表对象并将其映射到您的类。另外,sqlalchemy 中的映射类需要表上的主键,因此您必须添加一个。除此之外你还有其他问题吗?如果是这样,您可以粘贴您更新的代码吗?
I'm the author of the related answer:
sqlalchemy dynamic mapping
I have this answer to another question, which I think is even more related - it could even be a duplicate:
Database on the fly with scripting languages
As you can see, to make it you need to create a table object and map it against your class. Also, mapped classes in sqlalchemy need a primary key on the table, so you have to add one. Are you having any other problem besides that? If so, can you paste your updated code?