pulled apart main to make a self-contained author.py... Weird use of importing from __main__ rather than main.py, and ordering the import to after the db object was created seems to be the secret sauce

author.py

@@ -1,8 +1,68 @@
 from wtforms import SubmitField, StringField, HiddenField, validators, Form
+from flask import request, render_template
+from __main__ import db, app, ma
 
+################################################################################
+# Class describing Author in the database, and via sqlalchemy, connected to the DB as well
+################################################################################
+class Author(db.Model):
+    id = db.Column(db.Integer, unique=True, nullable=False, primary_key=True)
+    firstnames = db.Column(db.String(50), unique=False, nullable=False)
+    surname = db.Column(db.String(30), unique=False, nullable=False)
+
+    def __repr__(self):
+        return "<id: {}, firstnames: {}, surname: {}>".format(self.id,self.firstnames, self.surname)
+
+################################################################################
+# Helper class that inherits a .dump() method to turn class Author into json / useful in jinja2
+################################################################################
+class AuthorSchema(ma.SQLAlchemyAutoSchema):
+    class Meta: model = Author
+
+################################################################################
+# Helper class that defines a form for author, used to make html <form>, with field validation (via wtforms)
+################################################################################
 class AuthorForm(Form):
     id = HiddenField()
     firstnames = StringField('FirstName(s):', [validators.DataRequired()])
     surname = StringField('Surname:', [validators.DataRequired()])
     submit = SubmitField('Save' )
     delete = SubmitField('Delete' )
+
+################################################################################
+# Routes for author data
+#
+# /authors -> GET only -> prints out list of all authors
+################################################################################
+@app.route("/authors", methods=["GET"])
+def authors():
+    authors = Author.query.all()
+    return render_template("authors.html", authors=authors)
+
+################################################################################
+# /author/<id> -> GET/POST(save or delete) -> shows/edits/delets a single author
+################################################################################
+@app.route("/author/<id>", methods=["GET", "POST"])
+def author(id):
+    ### DDP: should this be request.form or request.values?
+    alert="Success"
+    author_form = AuthorForm(request.form)
+    if request.method == 'POST' and author_form.validate():
+        id = request.form['id']
+        author = Author.query.get(id)
+        try:
+            request.form['submit']
+        except:
+            message="Sorry, Deleting unsupported at present"
+            alert="Danger"
+        else:
+            print( "seems to be saving" )
+            author.firstnames = request.form['firstnames']
+            author.surname = request.form['surname']
+            db.session.commit()
+            message="Successfully Updated Author (id={})".format(id)
+    else:
+        author = Author.query.get(id)
+        author_form = AuthorForm(request.values, obj=author)
+        message=""
+    return render_template("author.html", author=author, alert=alert, message=message, author_form=author_form)

main.py

@@ -3,20 +3,20 @@ from flask import render_template
 from flask import request
 from flask_sqlalchemy import SQLAlchemy
 from flask_marshmallow import Marshmallow
-from author import AuthorForm
 from flask_bootstrap import Bootstrap
 
-
-DB_URL = 'postgresql+psycopg2://ddp:NWNlfa01@127.0.0.1:5432/library'
 app = Flask(__name__)
+### what is this value? I gather I should chagne it?
+DB_URL = 'postgresql+psycopg2://ddp:NWNlfa01@127.0.0.1:5432/library'
 app.config['SQLALCHEMY_DATABASE_URI'] = DB_URL
 app.config['SQLALCHEMY_TRACK_MODIFICATIONS'] = False
-### what is this value? I gather I should chagne it?
 app.config.from_mapping( SECRET_KEY=b'\xd6\x04\xbdj\xfe\xed$c\x1e@\xad\x0f\x13,@G')
 db = SQLAlchemy(app)
 ma = Marshmallow(app)
 Bootstrap(app)
 
+from author import Author, AuthorForm, AuthorSchema
+
 ####################################### CLASSES / DB model #######################################
 book_author_link = db.Table('book_author_link', db.Model.metadata,
     db.Column('book_id', db.Integer, db.ForeignKey('book.id')),
@@ -64,14 +64,6 @@ class Book(db.Model):
     def __repr__(self):
         return "<id: {}, author: {}, title: {}, year_published: {}, rating: {}, condition: {}, owned: {}, covertype: {}, notes: {}, blurb: {}, created: {}, modified: {}, publisher: {}>".format(self.id, self.author, self.title, self.year_published, self.rating, self.condition, self.owned, self.covertype, self.notes, self.blurb, self.created, self.modified, self.publisher )
 
-class Author(db.Model):
-    id = db.Column(db.Integer, unique=True, nullable=False, primary_key=True)
-    firstnames = db.Column(db.String(50), unique=False, nullable=False)
-    surname = db.Column(db.String(30), unique=False, nullable=False)
-
-    def __repr__(self):
-        return "<id: {}, firstnames: {}, surname: {}>".format(self.id,self.firstnames, self.surname)
-
 class Publisher(db.Model):
     id = db.Column(db.Integer, unique=True, nullable=False, primary_key=True)
     name = db.Column(db.String(50), unique=False, nullable=False)
@@ -87,10 +79,6 @@ class Genre_Lst(db.Model):
     def __repr__(self):
         return "<id: {}, genre: {}>".format(self.id, self.genre)
 
-### setup serializer schemas, to make returning books/authors easier
-class AuthorSchema(ma.SQLAlchemyAutoSchema):
-    class Meta: model = Author
-
 class PublisherSchema(ma.SQLAlchemyAutoSchema):
     class Meta: model = Publisher
 
@@ -158,36 +146,6 @@ def book(id):
 
     return render_template("book.html", books=book_s, subs=sub_book )
 
-@app.route("/authors", methods=["GET"])
-def authors():
-    authors = Author.query.all()
-    return render_template("authors.html", authors=authors)
-
-@app.route("/author/<id>", methods=["GET", "POST"])
-def author(id):
-    ### DDP: should this be request.form or request.values?
-    alert="Success"
-    author_form = AuthorForm(request.form)
-    if request.method == 'POST' and author_form.validate():
-        id = request.form['id']
-        author = Author.query.get(id)
-        try:
-            request.form['submit']
-        except:
-            message="Sorry, Deleting unsupported at present"
-            alert="Danger"
-        else:
-            print( "seems to be saving" )
-            author.firstnames = request.form['firstnames']
-            author.surname = request.form['surname']
-            db.session.commit()
-            message="Successfully Updated Author (id={})".format(id)
-    else:
-        author = Author.query.get(id)
-        author_form = AuthorForm(request.values, obj=author)
-        message=""
-    return render_template("author.html", author=author, alert=alert, message=message, author_form=author_form)
-    
 @app.route("/", methods=["GET"])
 def main_page():
     return render_template("main.html")