If you want to get an attribute of an object where the name of the
attribute is variable, you can use the getattr function:
attrname = "lastname"
column = getattr(User, attrname)
for item in session.query(column):
print(item)
or:
attrname = "lastname"
for user in session.query(User):
value = getattr(user, attrname)
print(value)
Simon
On Wed, Aug 19, 2020 at 3:20 PM Mike Bayer <[email protected]> wrote:
>
> __table__ is public (private would be a single or double underscore prefix
> only), but also you could use inspect(cls).column_attrs:
>
> https://docs.sqlalchemy.org/en/13/orm/mapping_api.html?highlight=column_attrs#sqlalchemy.orm.Mapper.column_attrs
>
>
>
> On Wed, Aug 19, 2020, at 1:22 AM, Dale Preston wrote:
>
> Thanks. The label is an interesting option; I'll look into that.
>
> On a StackOverflow thread, I got row.__table__.columns which I can iterate
> over and test the key, allowing me to get the column I need but I have to
> loop through all the columns until I find the one I want for each row because
> columns doesn't have an index either. I also don't like using a private
> property but I guess (hope) __table__ would always be there.
> On Tuesday, August 18, 2020 at 6:05:49 PM UTC-5 Mike Bayer wrote:
>
>
>
> On Tue, Aug 18, 2020, at 5:20 PM, Dale Preston wrote:
>
> I'm using sqlalchemy 1.3.18. I'm trying to write an app that looks at data
> from an ORM declarative table without necessarily knowing the table
> definition.
>
> What I am looking for is a way to get a single object (row in resultSet),
> having the name of column[1] is "lastname", and having "lastname" as a string
> in memory, how can I get the value of the "lastname" field from the row in
> resultSet?
>
> It's easy if I know in code that the row has a lastname property and I can
> use row.lastname but I want to do something like row["lastname"] or
> row.columns["lastname"] if there's a way.
>
>
> to get individual columns in the row you query for those columns directly:
>
>
> row = sess.query(User.lastname).first()
>
> print(row.lastname)
>
>
> otherwise you can always label a column if you need:
>
> row = sess.query(User.anything.label("lastname")).first()
>
> print(row.lastname)
>
>
>
>
>
>
>
>
> I'm using reflection to get the columns for the table. Here's some code I
> tried:
>
> class Users(Base):
> __tablename__ = 'users'
> userid = Column(String(80), primary_key=True)
> lastname = Column(String(40), nullable=False)
> firstname = Column(String(40), nullable=False)
> emailaddress = Column(String(80), nullable=False)
>
> def ReflectTableColumns(DbEngine, meta, targetTable):
> tableschema = Table(targetTable, meta, autoload=True,
> autoload_with=DbEngine)
> cols = dict()
> for c in tableschema.columns:
> print("{0}\t|\t{1}".format(c.name, c.type))
> cols[c.name] = c.type
>
> return cols
>
> def GetUsers():
> DBSession = sessionmaker(bind=Engine)
> session = DBSession()
> ShowTableData(session.query(Users).all(), 'users')
>
>
> def ShowTableData(resultSet, tablename):
> columns = ReflectTableColumns(Engine, Base.metadata, tablename)
> columnNames = list(columns.keys())
> print (type(resultSet))
> for row in resultSet:
> print (row.items[columnNames[1]])
> print (row.columns[columnNames[1]])
> print (row[columnNames[1]])
>
> GetUsers()
>
>
> --
> SQLAlchemy -
> The Python SQL Toolkit and Object Relational Mapper
>
> http://www.sqlalchemy.org/
>
> To post example code, please provide an MCVE: Minimal, Complete, and
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>
> --
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> The Python SQL Toolkit and Object Relational Mapper
>
> http://www.sqlalchemy.org/
>
> To post example code, please provide an MCVE: Minimal, Complete, and
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> SQLAlchemy -
> The Python SQL Toolkit and Object Relational Mapper
>
> http://www.sqlalchemy.org/
>
> To post example code, please provide an MCVE: Minimal, Complete, and
> Verifiable Example. See http://stackoverflow.com/help/mcve for a full
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--
SQLAlchemy -
The Python SQL Toolkit and Object Relational Mapper
http://www.sqlalchemy.org/
To post example code, please provide an MCVE: Minimal, Complete, and Verifiable
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