[update] Remove foreign key constraints

.gitignore

@@ -1,4 +1,6 @@
 __pycache__/
 .env
 app.log
-.DS_Store
+.DS_Store
+migrations/__pycache__/
+migrations/*.pycg

app/__init__.py

@@ -8,6 +8,7 @@ from app.errors import register_error_handlers
 from flask_sqlalchemy import SQLAlchemy
 from flask_migrate import Migrate
 
+
 db = SQLAlchemy()
 migrate = Migrate()
 
@@ -36,7 +37,7 @@ def create_app():
     # Error Handlers
     register_error_handlers(app)
     
-
+    from . import models
     # Database and Migrations
     db.init_app(app)
     

app/models/account.py

@@ -6,13 +6,22 @@ class Account(db.Model):
     __table_args__ = {'schema': 'flask_app'} 
 
     id = db.Column(db.String(50), primary_key=True)  
-    customer_id = db.Column(db.String(50), db.ForeignKey('customer.id'), nullable=False)
+    customer_id = db.Column(db.String(50), nullable=False)
     account_type = db.Column(db.String(50))
     status = db.Column(db.String(20), default='active')
     lien_amount = db.Column(db.Float, default=0.0)
     created_at = db.Column(db.DateTime, default=datetime.utcnow)
     updated_at = db.Column(db.DateTime, default=datetime.utcnow, onupdate=datetime.utcnow)
 
+    # Database relationship
+    # customer = db.relationship(
+    #     'Customer',
+    #     primaryjoin='Account.customer_id == Customer.id',
+    #     backref='accounts',
+    #     foreign_keys=[customer_id],
+    #     viewonly=True
+    # )
+
     def __repr__(self):
         return f'<Account {self.id}>'
     

app/models/customer.py

@@ -11,5 +11,6 @@ class Customer(db.Model):
     created_at = db.Column(db.DateTime, default=datetime.utcnow)
     updated_at = db.Column(db.DateTime, default=datetime.utcnow, onupdate=datetime.utcnow)
 
+
     def __repr__(self):
         return f'<Customer {self.id}>'

app/models/loan.py

@@ -7,8 +7,8 @@ class Loan(db.Model):
     __table_args__ = {'schema': 'flask_app'} 
 
     id = db.Column(db.String(50), primary_key=True) 
-    customer_id = db.Column(db.String(50), db.ForeignKey('customer.id'), nullable=False)
-    account_id = db.Column(db.String(50), db.ForeignKey('account.id'), nullable=False)
+    customer_id = db.Column(db.String(50), nullable=False)
+    account_id = db.Column(db.String(50), nullable=False)
     product_id = db.Column(db.String(20), nullable=False)
     principal_amount = db.Column(db.Float, nullable=False)
     status = db.Column(db.String(20), default='pending')

app/models/transaction.py

@@ -6,7 +6,7 @@ class Transaction(db.Model):
     __table_args__ = {'schema': 'flask_app'} 
 
     id = db.Column(db.String(50), primary_key=True)
-    account_id = db.Column(db.String(50), db.ForeignKey('account.id'), nullable=False)
+    account_id = db.Column(db.String(50), nullable=False)
     type = db.Column(db.String(50), nullable=False)
     amount = db.Column(db.Float, nullable=False)
     status = db.Column(db.String(20), default='pending')

migrations/env.py

@@ -0,0 +1,113 @@
+import logging
+from logging.config import fileConfig
+
+from flask import current_app
+
+from alembic import context
+
+# this is the Alembic Config object, which provides
+# access to the values within the .ini file in use.
+config = context.config
+
+# Interpret the config file for Python logging.
+# This line sets up loggers basically.
+fileConfig(config.config_file_name)
+logger = logging.getLogger('alembic.env')
+
+
+def get_engine():
+    try:
+        # this works with Flask-SQLAlchemy<3 and Alchemical
+        return current_app.extensions['migrate'].db.get_engine()
+    except (TypeError, AttributeError):
+        # this works with Flask-SQLAlchemy>=3
+        return current_app.extensions['migrate'].db.engine
+
+
+def get_engine_url():
+    try:
+        return get_engine().url.render_as_string(hide_password=False).replace(
+            '%', '%%')
+    except AttributeError:
+        return str(get_engine().url).replace('%', '%%')
+
+
+# add your model's MetaData object here
+# for 'autogenerate' support
+# from myapp import mymodel
+# target_metadata = mymodel.Base.metadata
+config.set_main_option('sqlalchemy.url', get_engine_url())
+target_db = current_app.extensions['migrate'].db
+
+# other values from the config, defined by the needs of env.py,
+# can be acquired:
+# my_important_option = config.get_main_option("my_important_option")
+# ... etc.
+
+
+def get_metadata():
+    if hasattr(target_db, 'metadatas'):
+        return target_db.metadatas[None]
+    return target_db.metadata
+
+
+def run_migrations_offline():
+    """Run migrations in 'offline' mode.
+
+    This configures the context with just a URL
+    and not an Engine, though an Engine is acceptable
+    here as well.  By skipping the Engine creation
+    we don't even need a DBAPI to be available.
+
+    Calls to context.execute() here emit the given string to the
+    script output.
+
+    """
+    url = config.get_main_option("sqlalchemy.url")
+    context.configure(
+        url=url, target_metadata=get_metadata(), literal_binds=True
+    )
+
+    with context.begin_transaction():
+        context.run_migrations()
+
+
+def run_migrations_online():
+    """Run migrations in 'online' mode.
+
+    In this scenario we need to create an Engine
+    and associate a connection with the context.
+
+    """
+
+    # this callback is used to prevent an auto-migration from being generated
+    # when there are no changes to the schema
+    # reference: http://alembic.zzzcomputing.com/en/latest/cookbook.html
+    def process_revision_directives(context, revision, directives):
+        if getattr(config.cmd_opts, 'autogenerate', False):
+            script = directives[0]
+            if script.upgrade_ops.is_empty():
+                directives[:] = []
+                logger.info('No changes in schema detected.')
+
+    conf_args = current_app.extensions['migrate'].configure_args
+    if conf_args.get("process_revision_directives") is None:
+        conf_args["process_revision_directives"] = process_revision_directives
+
+    connectable = get_engine()
+
+    with connectable.connect() as connection:
+        context.configure(
+            connection=connection,
+            target_metadata=get_metadata(),
+            **conf_args
+        )
+
+        with context.begin_transaction():
+            context.run_migrations()
+
+
+if context.is_offline_mode():
+    run_migrations_offline()
+else:
+    run_migrations_online()

migrations/versions/4a12e1b143a4_create_tables.py

@@ -0,0 +1,74 @@
+"""Create tables
+
+Revision ID: 4a12e1b143a4
+Revises: 
+Create Date: 2025-03-28 09:24:49.669509
+
+"""
+from alembic import op
+import sqlalchemy as sa
+
+
+# revision identifiers, used by Alembic.
+revision = '4a12e1b143a4'
+down_revision = None
+branch_labels = None
+depends_on = None
+
+
+def upgrade():
+    # ### commands auto generated by Alembic - please adjust! ###
+    op.create_table('accounts',
+    sa.Column('id', sa.String(length=50), nullable=False),
+    sa.Column('customer_id', sa.String(length=50), nullable=False),
+    sa.Column('account_type', sa.String(length=50), nullable=True),
+    sa.Column('status', sa.String(length=20), nullable=True),
+    sa.Column('lien_amount', sa.Float(), nullable=True),
+    sa.Column('created_at', sa.DateTime(), nullable=True),
+    sa.Column('updated_at', sa.DateTime(), nullable=True),
+    sa.PrimaryKeyConstraint('id'),
+    schema='flask_app'
+    )
+    op.create_table('customers',
+    sa.Column('id', sa.String(length=50), nullable=False),
+    sa.Column('msisdn', sa.String(length=20), nullable=False),
+    sa.Column('country_code', sa.String(length=3), nullable=False),
+    sa.Column('created_at', sa.DateTime(), nullable=True),
+    sa.Column('updated_at', sa.DateTime(), nullable=True),
+    sa.PrimaryKeyConstraint('id'),
+    sa.UniqueConstraint('msisdn'),
+    schema='flask_app'
+    )
+    op.create_table('loans',
+    sa.Column('id', sa.String(length=50), nullable=False),
+    sa.Column('customer_id', sa.String(length=50), nullable=False),
+    sa.Column('account_id', sa.String(length=50), nullable=False),
+    sa.Column('product_id', sa.String(length=20), nullable=False),
+    sa.Column('principal_amount', sa.Float(), nullable=False),
+    sa.Column('status', sa.String(length=20), nullable=True),
+    sa.Column('created_at', sa.DateTime(), nullable=True),
+    sa.Column('updated_at', sa.DateTime(), nullable=True),
+    sa.PrimaryKeyConstraint('id'),
+    schema='flask_app'
+    )
+    op.create_table('transactions',
+    sa.Column('id', sa.String(length=50), nullable=False),
+    sa.Column('account_id', sa.String(length=50), nullable=False),
+    sa.Column('type', sa.String(length=50), nullable=False),
+    sa.Column('amount', sa.Float(), nullable=False),
+    sa.Column('status', sa.String(length=20), nullable=True),
+    sa.Column('created_at', sa.DateTime(), nullable=True),
+    sa.Column('updated_at', sa.DateTime(), nullable=True),
+    sa.PrimaryKeyConstraint('id'),
+    schema='flask_app'
+    )
+    # ### end Alembic commands ###
+
+
+def downgrade():
+    # ### commands auto generated by Alembic - please adjust! ###
+    op.drop_table('transactions', schema='flask_app')
+    op.drop_table('loans', schema='flask_app')
+    op.drop_table('customers', schema='flask_app')
+    op.drop_table('accounts', schema='flask_app')
+    # ### end Alembic commands ###