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sqlalchemy.exc.OperationalError: (sqlite3.OperationalError) no such table: items

I don't understand why I have this error. Please explain the error.
I used official documentation.
I run Pipenv virtual env:
python 3.8.2
sqlalchemy 1.3.16
You can try run this code too.
import enum
from sqlalchemy import create_engine, Column, Integer, String, Enum
from sqlalchemy.ext.declarative import declarative_base
from sqlalchemy.orm import sessionmaker
engine = create_engine('sqlite:///:memory:', echo=True)
Base = declarative_base()
Session = sessionmaker(bind=engine)
session = Session()
class Type(str, enum.Enum):
ONE = "one"
TWO = "two"
class Item(Base):
__tablename__ = 'items'
id = Column(Integer, primary_key=True, index=True)
name = Column(String, unique=True, index=True)
type = Column(Enum(Type), default=Type.ONE, nullable=False)
item = Item(name="item_name", type="one")
session.add(item)
print(Item.__table__)
session.commit()
for name in session.query(Item.name):
print(name)

I added:
engine = create_engine('sqlite:///:memory:', echo=True)
Base = declarative_base()
Base.metadata.create_all(bind=engine)
Session = sessionmaker(bind=engine)
session = Session()
It creates the tables in the database (there are ways of using SQLAlchemy with preexisting tables, so an explicit instruction isd necessary).

In case it ends up helping someone, my issue was due to using an in memory sqlite db to unittest an API. Pytest would set up the database and tables with one connection while the API would create its own separate connection when the test were hitting endpoints. This ultimately solved it for me.
engine = create_engine("sqlite:///:memory:", poolclass=StaticPool, connect_args={'check_same_thread': False})
Ref: https://docs.sqlalchemy.org/en/14/dialects/sqlite.html#using-a-memory-database-in-multiple-threads

SQLAlchemy: how to create dynamic columns multiple times

I succeeded to create a sql table with columns defined dynamically, thanks to python class reflexion.
But I cannot run the code more than one time.
For instance, the following import_file , should create a static table and a dynamic table with specific columns.
It works if I run it one time. But the second time it crashs and returns the following error :
Table 'dynamic' is already defined for this MetaData instance
Code example :
from sqlalchemy import Column, Integer, String, Float, Boolean, Table
from sqlalchemy import create_engine, MetaData
from sqlalchemy.ext.declarative import declarative_base
from sqlalchemy.orm import sessionmaker, relationship
from sqlalchemy.orm import clear_mappers
import os
def import_file(filename, columns):
path = filename
if os.path.exists(path):
os.remove(path)
engine = create_engine(f"sqlite:///{path}", echo=True)
clear_mappers()
Base = declarative_base()
class StaticTable(Base):
__tablename__ = "static"
id = Column(Integer, primary_key=True)
name = Column(String)
class DynamicTable(Base):
__tablename__ = "dynamic"
id = Column(Integer, primary_key=True)
for c in columns:
setattr(DynamicTable,c,Column(String))
Base.metadata.create_all(engine)
import_file("test.db", columns = ["age","test"]) # WORKS
import_file("test2.db", columns= ["id","age","foo","bar"]) # NOT WORKING
I try to use sqlalchemy.orm.clear_mappers, but unsucessfully.
Any idea how can I resolve it ?

I think that it is not full you code, because conflicts on Base.metadata
Mappers for link on orm classes and tables, you have defined tables.
You can try somethink like that
import_file("test.db", columns = ["age","test"])
Base.metadata.clear()
sqlalchemy.orm.clear_mappers()
import_file("test2.db", columns= ["id","age","foo","bar"])

SQLAlchemy: update & delete value from database

I'm newer in SQLAlchemy I use some examples to create table and insert information to it and it's working 100% .
But what I didn't find is some example for how can I update & delete some information from the database.
What I'm doing is :
from sqlalchemy import Column, ForeignKey, Integer, String
from sqlalchemy.ext.declarative import declarative_base
from sqlalchemy.orm import sessionmaker
from sqlalchemy import create_engine
Base = declarative_base()
## create
class Person(Base):
__tablename__ = 'person'
id = Column(Integer, primary_key=True)
name = Column(String(250), nullable=False)
engine = create_engine('sqlite:///database.db')
Base.metadata.create_all(engine)
## insert
Base.metadata.bind = engine
DBSession = sessionmaker(bind=engine)
session = DBSession()
new_person = Person(name='new person')
session.add(new_person)
session.commit()
## fetch
getperson = session.query(Person).first()
print getperson.name
# this will print : new person
# I need some example to how can I update and delete this : new person
So in this code it'll print "new person" my question is how can I update or delete it ?

Here's some example on each CRUD operation in sqlalchemy (ommiting Create, Read as you already know how to perform those):
First, necessary imports and configs for any operation:
from sqlalchemy import create_engine
from sqlalchemy.orm import sessionmaker
# Category, Item, User are my tables
from database_setup import Base, Category, Item, User
# Generating session to connect to the db's ORM
engine = create_engine('sqlite:///catalogwithusers.db') # my db
Base.metadata.bind = engine
DBSession = sessionmaker(bind = engine)
session = DBSession()
Then peforming an update:
# Get the item filtering by it's id using a one() query on Item table
# If query is not empty, update the attributes, add query to session and commit
q = session.query(Item).filter_by(id=item_id).one()
if q != []:
q.name = edited_name
q.description = edited_description
session.add(q)
session.commit()
Finally, performing a deletion:
# Again get the item similarly to the example above
# Then if query returned results, use the delete method and commit
q = session.query(Item).filter_by(id=item_id).one()
if q != []:
session.delete(q)
session.commit()
These examples are taken from here. I suggest you have a look. ORM Creation is inside database_setup.py and CRUD ops are performed inside project.py and populatecatalog.py.

Is Python Camelot tied to Elixir?

The docs for Camelot say that it uses Elixir models. Since SQLAlchemy has included declarative_base for a while, I had used that instead of Elixir for another app. Now I would like to use the SQLAlchemy/declarative models directly in Camelot.
There is a post on Stackoverflow that says Camelot is not tied to Elixir and that using different models would be possible but it doesn't say how.
Camelot's original model.py only has this content:
import camelot.types
from camelot.model import metadata, Entity, Field, ManyToOne, OneToMany, Unicode, Date, Integer, using_options
from camelot.view.elixir_admin import EntityAdmin
from camelot.view.forms import *
__metadata__ = metadata
I added my SQLAlchemy model and changed model.py to this:
import camelot.types
from camelot.model import metadata, Entity, Field, ManyToOne, OneToMany, Unicode, Date, using_options
from camelot.view.elixir_admin import EntityAdmin
from camelot.view.forms import *
from sqlalchemy import Column, Integer, String
from sqlalchemy.ext.declarative import declarative_base
Base = declarative_base()
__metadata__ = metadata
Base = declarative_base()
class Test(Base):
__tablename__ = "test"
id = Column(Integer, primary_key=True)
text = Column(String)
It didn't work. When I start main.py, I can see the GUI and Test in the sidebar, but can't see any rows. This is the tail of the traceback:
File "/usr/lib/python2.6/dist-packages/camelot/view/elixir_admin.py", line 52, in get_query
return self.entity.query
AttributeError: type object 'Test' has no attribute 'query'
This is the elixir_admin.py code for line 46-52:
#model_function
def get_query(self):
""":return: an sqlalchemy query for all the objects that should be
displayed in the table or the selection view. Overwrite this method to
change the default query, which selects all rows in the database.
"""
return self.entity.query
If this code is causing the problem, how do I overwrite the method to change the default query to make it work?
How can you use SQLAlchemy/declarative models in Camelot?

Here is some sample code on using Declarative to define a Movie model for Camelot, some explanation can be found here.
import sqlalchemy.types
from sqlalchemy import Column
from sqlalchemy.ext.declarative import ( declarative_base,
_declarative_constructor )
from camelot.admin.entity_admin import EntityAdmin
from camelot.model import metadata
import camelot.types
from elixir import session
class Entity( object ):
def __init__( self, **kwargs ):
_declarative_constructor( self, **kwargs )
session.add( self )
Entity = declarative_base( cls = Entity,
metadata = metadata,
constructor = None )
class Movie( Entity ):
__tablename__ = 'movie'
id = Column( sqlalchemy.types.Integer, primary_key = True )
name = Column( sqlalchemy.types.Unicode(50), nullable = False )
cover = Column( camelot.types.Image(), nullable = True )
class Admin( EntityAdmin ):
list_display = ['name']
form_display = ['name', 'cover']

Which version of Camelot are you using ?
With the current version of Camelot (11.12.30) it is possible to use Declarative through some
hacks. The upcoming version will make it much easier, while after this, the examples will be
ported to Declarative as well.

SQLAlchemy - Trying Eager loading.. Attribute Error

I access a a postgres table using SQLAlchemy. I want a query to have eagerloading.
from sqlalchemy.orm import sessionmaker, scoped_session, eagerload
from settings import DATABASE_USER, DATABASE_PASSWORD, DATABASE_HOST, DATABASE_PORT, DATABASE_NAME
from sqlalchemy import create_engine
from sqlalchemy import Table, Column, Integer, String, Boolean, MetaData, ForeignKey
from sqlalchemy.orm import mapper
from sqlalchemy.ext.declarative import declarative_base
def create_session():
engine = create_engine('postgres://%s:%s#%s:%s/%s' % (DATABASE_USER, DATABASE_PASSWORD, DATABASE_HOST, DATABASE_PORT, DATABASE_NAME), echo=True)
Session = scoped_session(sessionmaker(bind=engine))
return Session()
Base = declarative_base()
class Zipcode(Base):
__tablename__ = 'zipcode'
zipcode = Column(String(6), primary_key = True, nullable=False)
city = Column(String(30), nullable=False)
state = Column(String(30), nullable=False)
session = create_session()
query = session.query(Zipcode).options(eagerload('zipcode')).filter(Zipcode.state.in_(['NH', 'ME']))
#query = session.query(Zipcode.zipcode).filter(Zipcode.state.in_(['NH', 'ME']))
print query.count()
This fails with
AttributeError: 'ColumnProperty' object has no attribute 'mapper'
One without eagerloading returns the records correctly.
I am new to SQLAlchemy. I am not sure what the problem is. Any pointers?

You can only eager load on a relation property. Not on the table itself. Eager loading is meant for loading objects from other tables at the same time as getting a particular object. The way you load all the objects for a query will be simply adding all().
query = session.query(Zipcode).options(eagerload('zipcode')).filter(Zipcode.state.in_(['NH', 'ME'])).all()
The query will now be a list of all objects (rows) in the table and len(query) will give you the count.