Use tablename in QRCode

Use the tablename instead instead of an abbreviation.
The scanner client can thus directly get the name of the fields to use.

app/models.py

@@ -129,7 +129,14 @@ class QRCodeMixin:
     name = db.Column(db.String(50), nullable=False, unique=True)
 
     def image(self):
-        data = ','.join([self.code, str(self.id), self.name])
+        """Return a QRCode image to identify a record
+
+        The QRCode includes:
+             - the table name
+             - the id of the record
+             - the name of the record
+        """
+        data = ','.join([self.__tablename__, str(self.id), self.name])
         return qrcode.make(data, version=1, box_size=5)
 
     def __str__(self):
@@ -140,16 +147,14 @@ class QRCodeMixin:
 
 
 class Action(QRCodeMixin, db.Model):
-    code = 'AC'
+    pass
 
 
 class Manufacturer(QRCodeMixin, db.Model):
-    code = 'MA'
     items = db.relationship('Item', back_populates='manufacturer')
 
 
 class Model(QRCodeMixin, db.Model):
-    code = 'MO'
     description = db.Column(db.Text)
     items = db.relationship('Item', back_populates='model')
 
@@ -158,12 +163,10 @@ class Model(QRCodeMixin, db.Model):
 
 
 class Location(QRCodeMixin, db.Model):
-    code = 'LO'
     items = db.relationship('Item', back_populates='location')
 
 
 class Status(QRCodeMixin, db.Model):
-    code = 'ST'
     items = db.relationship('Item', back_populates='status')