added in loans support, also particular route for book_for_loan without markup used as div content on loan.html page via ajax load

loan.py

@@ -0,0 +1,79 @@
+from wtforms import SubmitField, StringField, HiddenField, validators, TextAreaField
+from flask_wtf import FlaskForm
+from flask import request, render_template
+from wtforms.fields.html5 import DateField
+from __main__ import db, app, ma
+
+################################################################################
+# Class describing Loan in the database, and via sqlalchemy, connected to the DB as well
+################################################################################
+class Loan(db.Model):
+    id = db.Column(db.Integer, unique=True, nullable=False, primary_key=True)
+    surname = db.Column(db.String(30), unique=False, nullable=False)
+    firstnames = db.Column(db.String(50), unique=False, nullable=False)
+    contact_details = db.Column(db.String(256), unique=False, nullable=False)
+    date_lent = db.Column(db.Date, 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 Loan into json / useful in jinja2
+################################################################################
+class LoanSchema(ma.SQLAlchemyAutoSchema):
+    class Meta:
+        model = Loan
+        ordered = True
+
+################################################################################
+# Helper class that defines a form for loan, used to make html <form>, with field validation (via wtforms)
+################################################################################
+class LoanForm(FlaskForm):
+    id = HiddenField()
+    firstnames = StringField('FirstName(s):', [validators.DataRequired()])
+    surname = StringField('Surname:', [validators.DataRequired()])
+    contact_details = TextAreaField('Contact Details:', [validators.DataRequired()])
+    surname = StringField('Surname:', [validators.DataRequired()])
+    date_lent = DateField('Date Lent:', format='%Y-%m-%d' )
+    submit = SubmitField('Save' )
+    delete = SubmitField('Delete' )
+
+################################################################################
+# Routes for loan data
+#
+# /loans -> GET only -> prints out list of all loans
+################################################################################
+@app.route("/loans", methods=["GET"])
+def loans():
+    loans = Loan.query.all()
+    return render_template("loans.html", loans=loans)
+
+################################################################################
+# /loan/<id> -> GET/POST(save or delete) -> shows/edits/delets a single loan
+################################################################################
+@app.route("/loan/<id>", methods=["GET", "POST"])
+def loan(id):
+    ### DDP: should this be request.form or request.values?
+    alert="Success"
+    loan_form = LoanForm(request.form)
+    if request.method == 'POST' and loan_form.validate_on_submit():
+        id = request.form['id']
+        loan = Loan.query.get(id)
+        try:
+            request.form['submit']
+        except:
+            message="Sorry, Deleting unsupported at present"
+            alert="Danger"
+        else:
+            loan.firstnames = request.form['firstnames']
+            loan.surname = request.form['surname']
+            loan.surname = request.form['surname']
+            loan.contact_details = request.form['contact_details']
+            loan.date_lent = request.form['date_lent']
+            db.session.commit()
+            message="Successfully Updated Loan (id={})".format(id)
+    else:
+        loan = Loan.query.get(id)
+        loan_form = LoanForm(request.values, obj=loan)
+        message=""
+    return render_template("loan.html", loan=loan, alert=alert, message=message, loan_form=loan_form)