I would like SQLAlchemy to return an error if the underlying SQLite3 database file does not exist.
I've looked around, and tried:
#!/usr/bin/env python3
from sqlalchemy import create_engine, Column, Integer
from sqlalchemy.orm import Session, declarative_base
Base = declarative_base()
class SomeTable(Base):
id = Column(Integer)
DB_SPECIFIER = 'sqlite+pysqlite:////tmp/non-exist.db?mode=rw'
engine = create_engine(DB_SPECIFIER, echo=False, future=True, connect_args={'uri': True})
session = Session(engine)
x = session.query(SomeTable)
I'd like the create_engine call to fail if /tmp/non-exist.db does not exist. I thought using this answer would work, but it did not.
Looks like it's in the docs, though fairly hidden:
https://docs.sqlalchemy.org/en/14/dialects/sqlite.html#uri-connections
So you'd do:
DB_SPECIFIER = 'sqlite:///file:/tmp/non-exist.db?mode=ro&uri=true'
engine = create_engine(DB_SPECIFIER, echo=False, future=True)
It picks this apart and sends arguments to the connection, the rest through to the URI. (You can also add some lock disabling and such there, if that helps, since it's read only).
Related
Hello I am new I had a question so I am trying to create a simple api using flask ..
the data I have is in CSV and I want to import it in to SQLlite file .. which I have done. and can access the data
after I data is loaded and I have conformed there is data. I try and get python to reflect the class .. as I need to confirm its there for flask ..
below is what I type.
Python:
Base = automap_base()
Base.prepare(engine, reflect=True)
Base.classes.keys()
I get nothing
know why I am getting nothing I its because there is no class set up before I load the data using pandas ..
below is the code I use to load the data to sqlite;
Base = declarative_base()
engine = create_engine("sqlite:///countrytwo.sqlite")
Base.metadata.create_all(engine)
file_name = 'us.csv'
df=pd.read_csv(file_name)
df.to_sql('us',con=engine, index_label='id', if_exists='replace')
## then to conform theirs data I do below ##
print (engine.table_names())
so do I know I need to set up the class first then load the data in to the sqlite file .. one does any one have a good webiste to do this ..
I would love a clue lead me to the answer but maybe not give me the answer ..
if this is unclear let me know I can load more code. thank you.
import sqlite3
import pandas as pd
import os
class readCSVintoDB():
def __init__(self):
'''
self.csvobj = csvOBJ
self.dbobj = dbOBJ
'''
self.importCSVintoDB()
def importCSVintoDB(self):
userInput= input("enter the path of the csv file: ")
csvfile = userInput
df = pd.read_csv(csvfile,sep=';')
#print("dataFrame Headers is {0}".format(df.columns))# display the Headers
dp = (df[['date','temperaturemin','temperaturemax']])
print(dp)
'''
check if DB file exist
if no create an empty db file
'''
if not(os.path.exists('./rduDB.db')):
open('./rduDB.db','w').close()
'''
connect to the DB and get a connection cursor
'''
myConn = sqlite3.connect('./rduDB.db')
dbCursor = myConn.cursor()
'''
Assuming i need to create a table of (Name,FamilyName,age,work)
'''
dbCreateTable = '''CREATE TABLE IF NOT EXISTS rduWeather
(id INTEGER PRIMARY KEY,
Date varchar(256),
TemperatureMin FLOAT,
TemperatureMax FLOAT)'''
dbCursor.execute(dbCreateTable)
myConn.commit()
'''
insert data into the database
'''
for i in dp:
print(i)
dbCursor.execute('''
INSERT INTO rduWeather VALUES (?,?,?,?)''', i)
myConn.commit()
mySelect=dbCursor.execute('''SELECT * from rduWeather WHERE (id = 10)''')
print(list(mySelect))
myConn.close()
test1 = readCSVintoDB()
I'm looking for a more pythonic way to update a field within a NamedTuple (from typing).
I get field name and value during runtime from a textfile und therefore used exec, but I believe, there must be a better way:
#!/usr/bin/env python3.6
# -*- coding: utf-8 -*-
from typing import NamedTuple
class Template (NamedTuple):
number : int = 0
name : str = "^NAME^"
oneInstance = Template()
print(oneInstance)
# If I know the variable name during development, I can do this:
oneInstance = oneInstance._replace(number = 77)
# I get this from a file during runtime:
para = {'name' : 'Jones'}
mykey = 'name'
# Therefore, I used exec:
ExpToEval = "oneInstance = oneInstance._replace(" + mykey + " = para[mykey])"
exec(ExpToEval) # How can I do this in a more pythonic (and secure) way?
print(oneInstance)
I guess, from 3.7 on, I could solve this issue with dataclasses, but I need it for 3.6
Using _replace on namedtuples can not be made "pythonic" whatsoever. Namedtuples are meant to be immutable. If you use a namedtuple other developers will expect that you do not intent to alter your data.
A pythonic approach is indeed the dataclass. You can use dataclasses in Python3.6 as well. Just use the dataclasses backport from PyPi.
Then the whole thing gets really readable and you can use getattrand setattr to address properties by name easily:
from dataclasses import dataclass
#dataclass
class Template:
number: int = 0
name: str = "^Name^"
t = Template()
# use setattr and getattr to access a property by a runtime-defined name
setattr(t, "name", "foo")
print(getattr(t, "name"))
This will result in
foo
I'm trying to write a quick script to open a family document, change the parameter group of 2 specified parameters, and then close and save the document. I've done multiple tests and I am able to change the parameter groups of the specified parameters, but the changes of the groups don't save back to the family file. When I open the newly saved family, the parameter groups revert back to their original group.
This is with Revit 2017.2.
The same script, when run in RPS in Revit 2018 will do as desired.
import clr
import os
clr.AddReference('RevitAPI')
clr.AddReference('RevitAPIUI')
from Autodesk.Revit.DB import *
from Autodesk.Revit.UI import UIApplication
from System.IO import Directory, SearchOption
searchstring = "*.rfa"
dir = r"C:\Users\dboghean\Desktop\vanity\2017"
docs = []
if Directory.Exists(dir):
files = Directory.GetFiles(dir, searchstring, SearchOption.AllDirectories)
for f in files:
name, extension = os.path.splitext(f)
name2, extension2 = os.path.splitext(name)
if extension2:
os.remove(f)
else:
docs.append(f)
else:
print("Directory does not exist")
doc = __revit__.ActiveUIDocument.Document
app = __revit__.Application
uiapp = UIApplication(app)
currentPath = doc.PathName
pgGroup = BuiltInParameterGroup.PG_GRAPHICS
for i in docs:
doc = app.OpenDocumentFile(i)
paramList = [i for i in doc.FamilyManager.Parameters]
t = Transaction(doc, "test")
t.Start()
for i in paramList:
if i.Definition.Name in ["Right Sidesplash Edge line", "Left Sidesplash Edge line"]:
i.Definition.ParameterGroup = pgGroup
t.Commit()
doc.Close(True)
Any ideas?
Thanks!
I can confirm that this happens in Revit 2017. Strange!
A simple way around it is to arbitrarily rename the parameter using doc.FamilyManager.RenameParameter, then rename it back to the original name.
So in your case this would be three additional lines of code after changing the Parameter group:
originalName = i.Definition.Name
doc.FamilyManager.RenameParameter(i, "temp")
doc.FamilyManager.RenameParameter(i, originalName)
Doesnt get to the root problem, but works around it
I am doing a project in Python, django rest framework. I am using haystack SearchQuerySet. My code is here.
from haystack import indexes
from Medications.models import Salt
class Salt_Index(indexes.SearchIndex, indexes.Indexable):
text = indexes.CharField(document=True, use_template=True)
name = indexes.CharField(model_attr='name',null=True)
slug = indexes.CharField(model_attr='slug',null=True)
if_i_forget = indexes.CharField(model_attr='if_i_forget',null=True)
other_information = indexes.CharField(model_attr='other_information',null=True)
precautions = indexes.CharField(model_attr='precautions',null=True)
special_dietary = indexes.CharField(model_attr='special_dietary',null=True)
brand = indexes.CharField(model_attr='brand',null=True)
why = indexes.CharField(model_attr='why',null=True)
storage_conditions = indexes.CharField(model_attr='storage_conditions',null=True)
side_effects = indexes.CharField(model_attr='side_effects',null=True)
def get_model(self):
return Salt
def index_queryset(self, using=None):
return self.get_model().objects.all()
and my views.py file is -
from django.views.generic import View
from haystack.query import SearchQuerySet
from django.core import serializers
class Medication_Search_View(View):
def get(self,request,format=None):
try:
get_data = SearchQuerySet().all()
print get_data
serialized = ss.serialize("json", [data.object for data in get_data])
return HttpResponse(serialized)
except Exception,e:
print e
my python manage.py rebuild_index is working fine (showing 'Indexing 2959 salts') but in my 'views.py' file , SearchQuerySet() is returning an empty query set...
I am very much worried for this. Please help me friends if you know the reason behind getting empty query set while I have data in my Salt model.
you should check app name it is case sensitive.try to write app name in small letters
My problem is solved now. The problem was that i had wriiten apps name with capital letters and the database tables were made in small letters(myapp_Student). so it was creating problem on database lookup.
I'm trying to get information from a SQLite DB (HDBC.sqlite3) to feed to a web view using the Scotty framework. I'm currently trying to complete a "grab all" or rather select all the information from the table and then return it to display on my web page that is running via Scotty. I've encountered an error and I'm having some trouble figuring out how to fix it.
Here is my error:
Controllers/Home.hs:42:44:
Couldn't match expected type `Data.Text.Lazy.Internal.Text'
with actual type `IO [[(String, SqlValue)]]'
In the expression: getUsersDB
In the first argument of `mconcat', namely
`["<p>/users/all</p><p>", getUsersDB, "</p>"]'
In the second argument of `($)', namely
`mconcat ["<p>/users/all</p><p>", getUsersDB, "</p>"]'
Here is my code:
import Control.Monad
import Web.Scotty (ScottyM, ActionM, get, html, param, text)
import Data.Monoid (mconcat)
import Controllers.CreateDb (createUserDB)
import Database.HDBC
import Database.HDBC.Sqlite3
import Control.Monad.Trans ( MonadIO(liftIO) )
import Data.Convertible
getAllUsers :: ScottyM()
getAllUsers = get "/users/all" $ do
html $ mconcat ["<p>/users/all</p><p>", getUsersDB , "</p>"]
getUsersDB = do
conn <- connectSqlite3 databaseFilePath
stmt <- prepare conn "SELECT name FROM users VALUES"
results <- fetchAllRowsAL stmt
disconnect conn
return (results)
run returns the number of rows modified :
https://hackage.haskell.org/package/HDBC-2.4.0.0/docs/Database-HDBC.html#v:run