sqlalchemy

问题 This question already has an answer here : Need classic mapper example for SqlAlchemy single table inheritance (1 answer) Closed 3 years ago . I need to use the classical mapping instead of the declarative, for the last two days I am trying to make inheritance work, I tried with the declarative style and it worked but whatever I tried I cant get it to work when using the old mapping style. class Item(object): def specialised_method(self): return "I am not special" class SpecialisedItem(Item):

问题 I come to you because i cannot fix an issues with pandas.DataFrame.to_sql() method. I've made the connection between my script and my database, i can send queries, but actually it's too slow for me. I would like to find a way to improve the performance of my script on this. Maybe someone will find a solution? Here is my code : engine = sqlalchemy.create_engine(con['sql']['connexion_string']) conn = engine.connect() metadata = sqlalchemy.Metadata() try : if(con['sql']['strategy'] == 'NEW'):

问题 For example: sql = "select a, b, c from tb" rs = engine.execute(sql) the columns' types in rs.cursor.description are python types, not sql types, so how can I get columns' sql types? 来源： https://stackoverflow.com/questions/44692892/how-to-get-columns-sql-type-queried-by-sqlalchemy

问题 In a (postgres) SQLAlchemy model/class, I have several columns that are 'price' columns. I have read that using numeric/money/float types for this sort of data is not a good idea, so I'm storing as INTs (pennies). I have created validators for these columns that will multiply the input value by 100 and cast to an INT upon insert and update, so that is taken care of. How do I do the reverse? When I select this data, I want to cast these values to a float and then divide by 100. I cannot seem

问题 For example: sql = "select a, b, c from tb" rs = engine.execute(sql) the columns' types in rs.cursor.description are python types, not sql types, so how can I get columns' sql types? 来源： https://stackoverflow.com/questions/44692892/how-to-get-columns-sql-type-queried-by-sqlalchemy

问题 In a (postgres) SQLAlchemy model/class, I have several columns that are 'price' columns. I have read that using numeric/money/float types for this sort of data is not a good idea, so I'm storing as INTs (pennies). I have created validators for these columns that will multiply the input value by 100 and cast to an INT upon insert and update, so that is taken care of. How do I do the reverse? When I select this data, I want to cast these values to a float and then divide by 100. I cannot seem

问题 I'm creating my DB from an existing shema and it's stored in :memory: . db = Database(filename=':memory:', schema='schema.sql') db.recreate() I now want to "link" this to SQL Alchemy. Followed different methods but could not get it right. My current attempt stands as follow: engine = create_engine('sqlite:///:memory:') Base = automap_base() Base.prepare(engine, reflect=True) User = Base.classes.user session = Session(engine) Much like the other stuff I tried this will throw AttributeError:

问题 I'm creating my DB from an existing shema and it's stored in :memory: . db = Database(filename=':memory:', schema='schema.sql') db.recreate() I now want to "link" this to SQL Alchemy. Followed different methods but could not get it right. My current attempt stands as follow: engine = create_engine('sqlite:///:memory:') Base = automap_base() Base.prepare(engine, reflect=True) User = Base.classes.user session = Session(engine) Much like the other stuff I tried this will throw AttributeError:

问题 I have 2 classes: class A(Base): id = Column(Integer, primary_key=True) name = Column(String) children = relationship('B') class B(Base): id = Column(Integer, primary_key=True) id_a = Column(Integer, ForeignKey('a.id')) name = Column(String) Now I need all object A which contains B with some name and A object will contain all B objects filtered. To achieve it I build query. query = db.session.query(A).join(B).options(db.contains_eager(A.children)).filter(B.name=='SOME_TEXT') Now I need only

问题 I am using flask + sqlalchemy + alembic + postgresql, and am trying to find a simple architecture to solve the following problem. I have a simple database structure, lets say two tables : -- Users -- UserItems My users are in several different domains. I would like to have several of this database structure. For that I have database schemas in SQL. I created the matching class structure using sqlalchemy decalrative_base, and end up with a MetaData object that isn't tied to a specific schema.