improved handling of empty DB; "tables,py" now contains verbatim code from sqlacodegen, eliminating the need for code reformatting

the_works/database.py

@@ -5,14 +5,21 @@ db = SQLAlchemy()
 def init_db(app):
   db.init_app(app)
   with app.app_context():
-    print(f"number of db tables is {len(db.metadata.tables)}")
+    # check if database is empty and if so, populate it with fresh tables
-
+		#TODO: does it make sense to try and create all tables by default? Existing tables wouldn't be overwritten but what about DB constraints ?
-    # populate an empty DB with fresh tables
-		#TODO: maybe add tables to metadata in any case since tables won't get overwritten
     if not len(db.metadata.tables):
-      from the_works.tables import add_tables
+      # import table classes from code that was generated via `sqlacodegen --generator tables sqlite:///the_works.sqlite > ./the_works/tables.py` in project root
-      add_tables(db.metadata)
+      import the_works.tables
-      db.metadata.create_all(db.engine)
-      print(f"and now number of db tables is {len(db.metadata.tables)}")
 
+      # filter the objects just imported for those of type sqlalchemy.Table
+      from sqlalchemy import Table
+      table_list = list(filter(lambda t: type(t) == Table, vars(the_works.tables).values()))
+
+      # Table objects imported from sqlacodegen code are associated with a random MetaData() object, so we have to re-associate them with the DB's metadata  
+      table_list = list(map(lambda t: t.to_metadata(db.metadata), table_list))
+
+      # create tables in DB )
+      db.metadata.create_all(db.engine)
+    
+    # generate declarative table objects by reflecting the DB
     db.reflect()

the_works/tables.py

@@ -1,39 +1,41 @@
-# File content is based on the output of `sqlacodegen --generator tables sqlite:///path/to/the_works.sqlite` 
+# file created via `sqlacodegen --generator tables sqlite:///path/to/the_works.sqlite > tables.py` 
 
 from sqlalchemy import Column, ForeignKey, Integer, LargeBinary, MetaData, Table, Text
 
-def add_tables(metadata):
+metadata = MetaData()
-  t_Genre = Table(
+
+
+t_Genre = Table(
     'Genre', metadata,
     Column('ID', Integer, primary_key=True),
     Column('Genre', Text, nullable=False)
-  )
+)
 
-  t_Herausgeber = Table(
+t_Herausgeber = Table(
     'Herausgeber', metadata,
     Column('ID', Integer, primary_key=True),
     Column('Name', Text, nullable=False)
-  )
+)
 
-  t_Pseudonym = Table(
+t_Pseudonym = Table(
     'Pseudonym', metadata,
     Column('ID', Integer, primary_key=True),
     Column('Pseudonym', Text, nullable=False)
-  )
+)
 
-  t_Sprache = Table(
+t_Sprache = Table(
     'Sprache', metadata,
     Column('ID', Integer, primary_key=True),
     Column('Sprache', Text, nullable=False)
-  )
+)
 
-  t_Textform = Table(
+t_Textform = Table(
     'Textform', metadata,
     Column('ID', Integer, primary_key=True),
     Column('Textform', Text, nullable=False)
-  )
+)
 
-  t_Titelbild = Table(
+t_Titelbild = Table(
     'Titelbild', metadata,
     Column('ID', Integer, primary_key=True),
     Column('Mimetype', Text, nullable=False),
@@ -44,28 +46,28 @@ def add_tables(metadata):
     Column('Bild', LargeBinary, nullable=False),
     Column('Thumbnail', LargeBinary, nullable=False),
     Column('sha256', Text, nullable=False, unique=True)
-  )
+)
 
-  t_Verlag = Table(
+t_Verlag = Table(
     'Verlag', metadata,
     Column('ID', Integer, primary_key=True),
     Column('Verlag', Text, nullable=False)
-  )
+)
 
-  t_Werksform = Table(
+t_Werksform = Table(
     'Werksform', metadata,
     Column('ID', Integer, primary_key=True),
     Column('Werksform', Text, nullable=False)
-  )
+)
 
-  t_Reihe = Table(
+t_Reihe = Table(
     'Reihe', metadata,
     Column('ID', Integer, primary_key=True),
     Column('Titel', Text, nullable=False),
     Column('Verlag', ForeignKey('Verlag.ID'))
-  )
+)
 
-  t_Text = Table(
+t_Text = Table(
     'Text', metadata,
     Column('ID', Integer, primary_key=True),
     Column('Titel', Text, nullable=False),
@@ -73,9 +75,9 @@ def add_tables(metadata):
     Column('Reihe', ForeignKey('Reihe.ID')),
     Column('Textform', ForeignKey('Textform.ID')),
     Column('Sprache', ForeignKey('Sprache.ID'))
-  )
+)
 
-  t_Werk = Table(
+t_Werk = Table(
     'Werk', metadata,
     Column('ID', Integer, primary_key=True),
     Column('Titel', Text, nullable=False),
@@ -92,15 +94,15 @@ def add_tables(metadata):
     Column('Titelbild', ForeignKey('Titelbild.ID')),
     Column('Klappentext', Text),
     Column('Anmerkungen', Text)
-  )
+)
 
-  t_Text_Genre = Table(
+t_Text_Genre = Table(
     'Text_Genre', metadata,
     Column('Text', ForeignKey('Text.ID'), primary_key=True),
     Column('Genre', ForeignKey('Genre.ID'), primary_key=True)
-  )
+)
 
-  t_Veroeffentlichung = Table(
+t_Veroeffentlichung = Table(
     'Veroeffentlichung', metadata,
     Column('ID', Integer, primary_key=True),
     Column('Text', ForeignKey('Text.ID'), nullable=False),
@@ -108,16 +110,16 @@ def add_tables(metadata):
     Column('AltTitel', Text),
     Column('AltUntertitel', Text),
     Column('Pseudonym', ForeignKey('Pseudonym.ID'), nullable=False)
-  )
+)
 
-  t_Werk_Genre = Table(
+t_Werk_Genre = Table(
     'Werk_Genre', metadata,
     Column('Werk', ForeignKey('Werk.ID'), primary_key=True),
     Column('Genre', ForeignKey('Genre.ID'), primary_key=True)
-  )
+)
 
-  t_Werk_Herausgeber = Table(
+t_Werk_Herausgeber = Table(
     'Werk_Herausgeber', metadata,
     Column('Herausgeber', ForeignKey('Herausgeber.ID'), primary_key=True),
     Column('Werk', ForeignKey('Werk.ID'), primary_key=True)
-  )
+)