add alembic initialization and add two tables

alembic.ini

@@ -0,0 +1,42 @@
+# A generic, single database configuration.
+
+[alembic]
+# path to migration scripts
+script_location = ./app/db/alembic
+
+# sqlalchemy.url = driver://user:pass@localhost/dbname configured in the .env.yaml file
+
+# Logging configuration
+[loggers]
+keys = root,sqlalchemy,alembic
+
+[handlers]
+keys = console
+
+[formatters]
+keys = generic
+
+[logger_root]
+level = WARN
+handlers = console
+qualname =
+
+[logger_sqlalchemy]
+level = WARN
+handlers =
+qualname = sqlalchemy.engine
+
+[logger_alembic]
+level = INFO
+handlers =
+qualname = alembic
+
+[handler_console]
+class = StreamHandler
+args = (sys.stderr,)
+level = NOTSET
+formatter = generic
+
+[formatter_generic]
+format = %(levelname)-5.5s [%(name)s] %(message)s
+datefmt = %H:%M:%S

app/db/alembic/env.py

@@ -0,0 +1,61 @@
+from logging.config import fileConfig
+
+from sqlalchemy import engine_from_config
+from sqlalchemy import pool
+
+from alembic import context
+
+import sys, pathlib
+sys.path.append(str(pathlib.Path(__file__).resolve().parents[3]))
+
+from app.utils.config_loader import ConfigLoader
+
+import pymysql
+pymysql.install_as_MySQLdb() # we are using python3
+
+# 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)
+
+# add your model's MetaData object here
+# for 'autogenerate' support
+# from myapp import mymodel
+# target_metadata = mymodel.Base.metadata
+from app.db.tables import sqlalchemy_orm
+target_metadata = sqlalchemy_orm.Base.metadata
+
+config.set_main_option("sqlalchemy.url", ConfigLoader().load_env()["MYSQL_CONNECTION"]) # we need to add this in main option, because the configuration of sqlalchemy.url is in .env.yaml, not in alembic.ini
+
+# 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 run_migrations_online():
+    """Run migrations in 'online' mode.
+
+    In this scenario we need to create an Engine
+    and associate a connection with the context.
+
+    """
+    connectable = engine_from_config(
+        config.get_section(config.config_ini_section),
+        prefix="sqlalchemy.",
+        poolclass=pool.NullPool,
+    )
+
+    with connectable.connect() as connection:
+        context.configure(
+            connection=connection, target_metadata=target_metadata
+        )
+
+        with context.begin_transaction():
+            context.run_migrations()
+
+
+run_migrations_online()

app/db/alembic/script.py.mako

@@ -0,0 +1,24 @@
+"""${message}
+
+Revision ID: ${up_revision}
+Revises: ${down_revision | comma,n}
+Create Date: ${create_date}
+
+"""
+from alembic import op
+import sqlalchemy as sa
+${imports if imports else ""}
+
+# revision identifiers, used by Alembic.
+revision = ${repr(up_revision)}
+down_revision = ${repr(down_revision)}
+branch_labels = ${repr(branch_labels)}
+depends_on = ${repr(depends_on)}
+
+
+def upgrade():
+    ${upgrades if upgrades else "pass"}
+
+
+def downgrade():
+    ${downgrades if downgrades else "pass"}

app/db/alembic/versions/5c2ce5113df2_change_comment_s_body_column_type_to_.py

@@ -0,0 +1,47 @@
+"""change comment's body column type to Text
+
+Revision ID: 5c2ce5113df2
+Revises: 
+Create Date: 2021-08-14 13:37:46.787734
+
+"""
+from alembic import op
+import sqlalchemy as sa
+
+
+# revision identifiers, used by Alembic.
+revision = '5c2ce5113df2'
+down_revision = None
+branch_labels = None
+depends_on = None
+
+
+def upgrade():
+    # ### commands auto generated by Alembic - please adjust! ###
+    op.create_table('comments',
+    sa.Column('id', sa.Integer(), nullable=False),
+    sa.Column('pull_request_id', sa.Integer(), nullable=False),
+    sa.Column('comment_id', sa.Integer(), nullable=False),
+    sa.Column('created_at', sa.TIMESTAMP(), nullable=False),
+    sa.Column('body', sa.Text(), nullable=True),
+    sa.PrimaryKeyConstraint('id')
+    )
+    op.create_table('pull_requests',
+    sa.Column('id', sa.Integer(), nullable=False),
+    sa.Column('owner_login', sa.VARCHAR(length=255), nullable=False),
+    sa.Column('repo_name', sa.VARCHAR(length=255), nullable=False),
+    sa.Column('number', sa.Integer(), nullable=False),
+    sa.Column('state', sa.VARCHAR(length=255), nullable=False),
+    sa.Column('created_at', sa.TIMESTAMP(), nullable=False),
+    sa.Column('updated_at', sa.TIMESTAMP(), nullable=True),
+    sa.Column('comment_or_not', sa.Boolean(), nullable=True),
+    sa.PrimaryKeyConstraint('id')
+    )
+    # ### end Alembic commands ###
+
+
+def downgrade():
+    # ### commands auto generated by Alembic - please adjust! ###
+    op.drop_table('pull_requests')
+    op.drop_table('comments')
+    # ### end Alembic commands ###

app/db/tables/sqlalchemy_orm.py

@@ -0,0 +1,24 @@
+from sqlalchemy.ext.declarative import declarative_base
+from sqlalchemy import Column, Integer, VARCHAR, TIMESTAMP, Boolean, Text
+
+Base = declarative_base()
+
+class PullRequest(Base):
+    __tablename__ = "pull_requests"
+    id = Column(Integer, primary_key=True)
+    owner_login = Column(VARCHAR(255), nullable=False)
+    repo_name = Column(VARCHAR(255), nullable=False)
+    number = Column(Integer, nullable=False)
+    state = Column(VARCHAR(255), nullable=False)
+    created_at = Column(TIMESTAMP, nullable=False)
+    updated_at = Column(TIMESTAMP, nullable=True)
+    comment_or_not = Column(Boolean, nullable=True)
+
+
+class Comment(Base):
+    __tablename__ = "comments"
+    id = Column(Integer, primary_key=True)
+    pull_request_id = Column(Integer, nullable=False)
+    comment_id = Column(Integer, nullable=False)
+    created_at = Column(TIMESTAMP, nullable=False)
+    body = Column(Text, nullable=True)