I tired to use the SqlAlchemy orm to build the api to insert the values into database from uploaded excel files. when I tested on the codes it kept showing the error:
TypeError: __init__() missing 1 required positional argument: 'id'
I've updated the id key to primary key, auto increment, unique and unsigned in my local MySql data base. I believe the system cannot insert the primary key automatically because it works if I assign the value to id manually
transaction_obj = Transaction(id=1, name="David", date="2018-03-03",
product="fruit", quantity=20, amount=12.55)
Here is model.py
from sqlalchemy import Table, MetaData, Column, Integer, String, DATE, DECIMAL,ForeignKey, DateTime
from sqlalchemy.orm import mapper
metadata = MetaData()
customers = Table('customers', metadata,
Column('id', Integer, primary_key=True),
Column('name', String(20)),
Column('phone', String(20)),
Column('address', String(45)),
Column('source_from', String(45))
)
class Customers(object):
def __init__(self, name, phone, address, source_from):
self.name = name
self.phone = phone
self.address = address
self.source_from = source_from
def __repr__(self):
return "<Customer(name='%s', phone='%s', address='%s', " \
"source_from='%s')" % (self.name, self.phone, self.address,
self.source_from)
mapper(Customers, customers)
transaction = Table('transaction', metadata,
Column('id', Integer, primary_key=True),
Column('name', String(20)),
Column('date', DateTime),
Column('product', String(20)),
Column('quantity', Integer),
Column('amount',DECIMAL(2))
)
class Transaction(object):
def __index__(self, name, date, product, quantity, amount):
self.name = name
self.date = date
self.product = product
self.quantity = quantity
self.amount = amount
def __repr__(self):
return "<Transaction(name='%s', date='%s', product='%s'," \
"quantity='%s', amount='%s')>" % (self.name, self.date,
self.product, self.quantity,
self.amount)
mapper(Transaction, transaction)
Here is my test coding: test.py
import json
import os
import os
import json
from sqlalchemy import create_engine
import config
import pandas as pd
conn = config.conn_str
def tran_test():
engine = create_engine(conn)
Session_class = sessionmaker(bind=engine)
Session = Session_class
# generate the object for the data we would like to insert
transaction_obj = Transaction(name="David", date="2018-03-03",
product="fruit", quantity=20, amount=12.55)
Session.add(transaction_obj)
Session.commit()
def test_uploaded_file(file):
df = pd.read_excel(file)
return df.info()
if __name__ == '__main__':
# set_env_by_setting('prod')
# conn_str = os.environ.get('ConnectionString')
# print(conn_str)
# test_uploaded_file("-1.xlsx")
tran_test()
I'm using SQLAlchemy==1.2.10, PyMySQL==0.9.2.
I'm doubting if I'm using the wrong format in model.py. Please advise. Thx.
While I'm not sure about the pattern you are using, (manually mapping to your table classes) I think you would have a much easier time making use of declarative_base which does this for you.
from sqlalchemy.ext.declarative import declarative_base
Base = declarative_base()
Then make sure your models inherit Base
from sqlalchemy import (
Column,
Integer,
String
)
class Customers(Base):
__tablename__ = 'customer'
id = Column(Integer, primary_key=True) # Auto-increment should be default
name = Column(String(20))
# Etc.
def __repr__(self):
return "<Customer(name='%s', phone='%s', address='%s', " \
"source_from='%s')" % (self.name, self.phone, self.address,
self.source_from)
And finally use Base to create your table:
Base.metadata.create_all(engine)
Here is a good reference to basic declarative use cases. It gets a little more complicated depending on how you are scaffolding your app but its a great starting point:
http://docs.sqlalchemy.org/en/latest/orm/extensions/declarative/basic_use.html
Related
I have an object
class Summary():
__tablename__ = 'employeenames'
name= Column('employeeName', String(128, collation='utf8_bin'))
date = Column('dateJoined', Date)
I want to patch Summary with a mock object
class Summary():
__tablename__ = 'employeenames'
name= Column('employeeName', String)
date = Column('dateJoined', Date)
or just patch name the field to name= Column('employeeName', String)
The reason I'm doing this is that I'm doing my tests in sqlite and some queries that are only for Mysql are interfering with my tests.
I think it would be difficult to mock the column. However you could instead conditionally compile the String type for Sqlite, removing the collation.
import sqlalchemy as sa
from sqlalchemy import orm
from sqlalchemy.ext.compiler import compiles
from sqlalchemy.types import String
#compiles(String, 'sqlite')
def compile_varchar(element, compiler, **kw):
type_expression = kw['type_expression']
type_expression.type.collation = None
return compiler.visit_VARCHAR(element, **kw)
Base = orm.declarative_base()
class Summary(Base):
__tablename__ = 'employeenames'
id = sa.Column(sa.Integer, primary_key=True)
name = sa.Column('employeeName', sa.String(128, collation='utf8_bin'))
date = sa.Column('dateJoined', sa.Date)
urls = ['mysql:///test', 'sqlite://']
for url in urls:
engine = sa.create_engine(url, echo=True, future=True)
Base.metadata.drop_all(engine)
Base.metadata.create_all(engine)
This script produces the expected output for MySQL:
CREATE TABLE employeenames (
id INTEGER NOT NULL AUTO_INCREMENT,
`employeeName` VARCHAR(128) COLLATE utf8_bin,
`dateJoined` DATE,
PRIMARY KEY (id)
)
but removes the collation for Sqlite:
CREATE TABLE employeenames (
id INTEGER NOT NULL,
"employeeName" VARCHAR(128),
"dateJoined" DATE,
PRIMARY KEY (id)
)
I'm using Python Sqlalchemy for MYSQL db. I wrote the following script to create the class object and then added some rows in the table.
from sqlalchemy import create_engine, MetaData, Table, Column, ForeignKey
from sqlalchemy.dialects.mysql.base import VARCHAR, LONGTEXT, INTEGER
from sqlalchemy.orm import sessionmaker
from sqlalchemy.ext.declarative import declarative_base
engine = create_engine("mysql+mysqldb://root:#localhost/mydb")
connection = engine.connect()
Session = sessionmaker(bind=engine)
session = Session()
Base = declarative_base()
metadata = MetaData()
class User(Base):
__tablename__ = 'User'
id = Column('id', INTEGER(display_width=11), primary_key=True, nullable=False)
email = Column('email', VARCHAR(charset='utf8mb4', collation='utf8mb4_0900_ai_ci', length=100), unique=True)
password = Column('password', VARCHAR(charset='utf8mb4', collation='utf8mb4_0900_ai_ci', length=45))
name = Column('name', VARCHAR(charset='utf8mb4', collation='utf8mb4_0900_ai_ci', length=100))
Now, I need to get all the rows from the table "User" so I am doing this:
user = session.query(User).all()
print(user)
but the output I am getting is not the table data but this:
[<__main__.User object at 0x7f10b0c6ebe0>, <__main__.User object at 0x7f10b0c6ec50>]
How would I get the actual data from the table? Any help would be appreciated
The output you will get is a tuple of records.
So, use a loop
users = session.query(User).all()
for user in users:
print (user)
print (user.id, user.email, user.password, user.name)
you should write __str__ method in User class something like:
class User(Base):
...
def __str__(self):
str_out = 'id={} email={} password={} name={}'
str_formated = str_out.format(self.id,self.email,self.password,self.name)
return str_formated
I'm trying to generate the JSON of my SQLAlchemy classes, I followed this example:
https://blogs.gnome.org/danni/2013/03/07/generating-json-from-sqlalchemy-objects/
It’s working very fine, but now I want to include all the data of the subclasses generated by the relationship of SQLAchemy. I've tried several things, the last one is trying to iterate over the subclases but I don't know why the method subclasses doesn't return anything. This is the function tojson modified:
def tojson(self):
res=self.columnitems
for cls in self.__class__.__subclasses__():
res[cls.__name__]=cls.tojson()
return res
Do you know any way to do it?
Thanks in advance
I can't comment yet but based on the information provided I'm assuming you are trying to generate a json from your (related) sqlalchemy classes. You can use the marshmallow (https://marshmallow.readthedocs.io/en/latest/) for this.
The (quick) example below shows how you can generate a json using marshmallow of two related tables.
from sqlalchemy import Column, Integer, String, Boolean
from sqlalchemy.ext.declarative import declarative_base
from sqlalchemy import create_engine, ForeignKey
from sqlalchemy.orm import sessionmaker, relationship
Base = declarative_base()
# Creating dummy classes...
class Owner(Base):
__tablename__ = 'owner'
id = Column('id', Integer, primary_key=True)
name = Column('name', String(250))
interested_in_cars = Column('interest', Boolean)
car = relationship('Car', uselist=False, back_populates="owner")
def __init__(self, name, interested_in_cars, id):
self.id = id
self.name = name
self.interested_in_cars = interested_in_cars
def __repr__(self):
return '< (id={id}) Owner: {name} - interested: {interested_in_cars} >'.format(id=self.id,
name=self.name,
interested_in_cars=self.interested_in_cars)
class Car(Base):
__tablename__ = 'car'
id = Column('id', Integer, primary_key=True)
brand = Column(String(250))
owner_id = Column(Integer, ForeignKey('owner.id'))
owner = relationship('Owner', back_populates='car')
def __init__(self, owner_id, brand):
self.owner_id = owner_id
self.brand = brand
def __repr__(self):
return '< Owner: {owner_id} - Car: {brand} >'.format(owner_id=self.owner_id, brand=self.brand)
engine = create_engine('sqlite:///')
session = sessionmaker()
session.configure(bind=engine)
ex_ses = session()
Base.metadata.create_all(engine)
owner_1 = Owner(interested_in_cars=True, name='Owner a', id=1)
owner_2 = Owner(interested_in_cars=False, name='Owner b', id=2)
ex_ses.add(owner_1)
ex_ses.add(owner_2)
# ID's - quick example
car_1 = Car(owner_id=1, brand='Car a')
car_2 = Car(owner_id=2, brand='Car b')
ex_ses.add(car_1)
ex_ses.add(car_2)
ex_ses.commit()
# Using marshmallow to generate the json
from marshmallow import Schema, fields, pprint
class OwnerShema(Schema):
id = fields.Int()
name = fields.String()
interested_in_cars = fields.Boolean()
car = fields.Nested('CarShema')
class CarShema(Schema):
id = fields.Int()
brand = fields.String()
# Example Owners and cars
owners_cars = ex_ses.query(Owner).all()
print('Owners and cars: ', owners_cars)
owners_cars_shema = OwnerShema()
pprint(owners_cars_shema.dump(owners_cars, many=True).data)
For more information see the marshmallow documentation (link provided above).
I have a question concerning the mapping of entities in SQLAlchemy.
I have a transient object, which already contains foreign keys to some persistent objects. I want that SQLAlchemy fetches the referenced objects and assigns them to their relationship-attributes. From the SQLAlchemy documentation, I thought that I have to use the merge-operation on the session to achieve this. But in my configuration, it doesn't work.
This is a minimum example demonstrating my problem:
# -*- coding: utf-8 -*-
from sqlalchemy import create_engine
from sqlalchemy.orm import mapper
from sqlalchemy import Table, Column, Integer, String, MetaData, ForeignKey
from sqlalchemy.orm import relationship, sessionmaker
class User(object):
def __init__(self, id, name, fullname, password, best_friend_id=None):
self.id = id
self.name = name
self.fullname = fullname
self.password = password
self.best_friend_id = best_friend_id
def __repr__(self):
return "<User('%s','%s', '%s')>" % (self.name, self.fullname, self.password)
class Dog(object):
def __init__(self, id, name):
self.id = id
self.name = name
def __repr__(self):
return "<User('%s','%s', '%s')>" % (self.name, self.fullname, self.password)
engine = create_engine('sqlite:///:memory:', echo=True)
Session = sessionmaker(bind=engine)
session = Session()
metadata = MetaData()
dogs_table = Table('dogs', metadata,
Column('id', Integer, primary_key=True),
Column('name', String),
)
users_table = Table('users', metadata,
Column('id', Integer, primary_key=True),
Column('name', String),
Column('fullname', String),
Column('password', String),
Column('best_friend_id', Integer, ForeignKey('dogs.id'))
)
metadata.create_all(engine)
mapper(User, users_table, properties={'best_friend': relationship(Dog, uselist=False)})
mapper(Dog, dogs_table)
dog = Dog(id=1, name='Hasso')
lordling = User(id=2, name='John', fullname='Miller', password='very_secret', best_friend_id=1)
session.add(dog)
session.commit()
merged_lordling = session.merge(lordling)
print str(merged_lordling.best_friend.name)
I expect that merged_lordling.best_friend contains the dog 'Hasso'. But it is still None.
I was bit by this same problem recently. Once you established a relationship, you should simply assign your Dog instance to User.best_friend directly, not explicitly using the foreign key. I don't know why exactly that happens, but while investigating a similar problem I realized that if you do that, SQLAlchemy doesn't populate the relationship property until you flushed all the related instances.
So, instead of:
dog = Dog(id=1, name='Hasso')
lordling = User(id=2, name='John', fullname='Miller', password='very_secret',
best_friend_id=1)
session.add(dog)
Simply do:
dog = Dog(id=1, name='Hasso')
lordling = User(id=2, name='John', fullname='Miller', password='very_secret',
best_friend=dog)
session.add(lordling)
Or even:
lordling = User(id=2, name='John', fullname='Miller', password='very_secret',
best_friend=Dog(id=1, name='Hasso'))
session.add(lordling)
As a general rule, avoid using the foreign key columns directly when you have a relationship established. Embrace the ORM, and only assign or query directly from foreign keys when you really have no other choice. I learned that the hard way.
Hello I am new with SQLalchemy and have some problems with inserting data in a column.
import sqlalchemy
from sqlalchemy import create_engine
from sqlalchemy.ext.declarative import declarative_base
from sqlalchemy import Column, Integer, String, ForeignKey, Boolean
from sqlalchemy.orm import relationship, backref
from sqlalchemy.orm import sessionmaker
engine = create_engine('sqlite:///test.db')
Base = declarative_base()
class Users(Base):
__tablename__ = 'users'
id = Column(Integer, primary_key=True)
name = Column(String, unique=True)
password = Column(String)
email = Column(String)
def __init__(self, name, password, email):
self._name = name
self._password = password
self._email = email
Base.metadata.create_all(engine)
Session = sessionmaker(bind=engine)
Session.configure(bind=engine)
session = Session()
dm_user = Users("Dungeonmaster", "123", "email")
print dm_user.name
print dm_user.password
print dm_user.email
session.add(dm_user)
our_user = session.query(Users).filter_by(name='Dungeonmaster').first()
session.commit()
I used sqlite studio to see if the data is added, and I see that a new row is being made (with a new id.) but the data name, password and email is not inserted.
With the print I see even before I try to add something goes wrong, but I don't know what. please help me out a bit
( dm_user = Users("Dungeonmaster", "123", "email") tried with single quotes as well (helped me before using sqlalchemy, but no difference here)
Your init method does not initialize the persistent columns. Try instead (remove underscores):
def __init__(self, name, password, email):
self.name = name
self.password = password
self.email = email