SQLAlchemy & Postgresql

[Peter Otten]

Buddy Peacock wrote:

> Hello group,
> I have a pretty good background in MySQL & MSSQL as well as VB & Php, but
> I am new to Python and Postgresql.
> 
> I am taking a class and working on a project to insert authors and books
> into a table.  My code for this is:
> ===============================================================
> import csv
> import os
> 
> from flask import Flask
> from sqlalchemy import create_engine
> from sqlalchemy.orm import scoped_session, sessionmaker
> 
> app = Flask(__name__)
> 
> # Configure session to use filesystem
> app.config["SESSION_PERMANENT"] = False
> app.config["SESSION_TYPE"] = "filesystem"
> # Session(app)
> 
> # Set up database
> engine = create_engine(os.getenv("DATABASE_URL"))
> db = scoped_session(sessionmaker(bind=engine))
> 
> print (os.getenv("DATABASE_URL"))
> 
> def main():
>     f = open("books.csv")
>     reader = csv.reader(f)
>     for isbn, title, author, year in reader:
>         if db.execute("SELECT * FROM authors WHERE name = :author",
> {"name": author}).rowcount == 0:
>             db.execute("INSERT INTO authors (name) VALUES (author)")
> 
>         print(f" {author} was read.")
>     db.commit()
> 
> if __name__ == "__main__":
>     main()
> ====================================================================
> If I comment out the "if" statement then the authors all print on screen.
> But when I run this with the if statement I am getting a message that
> says: ssqlalchemy.exc.StatementError: (sqlalchemy.exc.InvalidRequestError)
> A value is required for bind parameter 'author'
> [SQL: SELECT * FROM authors WHERE name = %(author)s]
> [parameters: [{'name': 'author'}]]
> 
> What am I missing?

The variable name for name is :author. Therefore I think you have to use
"author" as the key in the dict:

db.execute("SELECT * FROM authors WHERE name = :author", {"author": author})