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The specifics of how the migration environment are invoked. The exact specifics of how to connect are here, as well as The env.py script is part of the generated environment so that the way migrations run Procure a connection from that engine along with a transaction, and then invoke the migrationĮngine, using the connection as a source of database connectivity. It can be named anything, and a project that uses multiple databasesĮnv.py - This is a Python script that is run whenever the alembic migration tool is invoked.Īt the very least, it contains instructions to configure and generate a SQLAlchemy engine, Yourproject - this is the root of your application’s source code, or some directory within it.Īlembic - this directory lives within your application’s source tree and is the home of the The directory includes these directories/files: The structure of this environment, including some generated migration scripts, looks like: The environment isĬreated using the init command of Alembic, and is then customizable to suit the specific The migration environment is created just once,Īnd is then maintained along with the application’s source code itself. That is specific to a particular application. Usage of Alembic starts with creation of the Migration Environment. The local path and when invoked, will have access to the same Python moduleĮnvironment as that of the target project. The tutorial below assumes the alembic command line utility is present in This is not strictly necessary in all cases, however in the vast majority of

Project’s env.py script, will have access to your application’s models. Usually using a Python virtual environment, so that when the alembicĬommand is run, the Python script which is invoked by alembic, namely your Installed in the same module / Python path as that of the target project,

To begin, make sure Alembic is installed as described at Installation.Īs stated in the linked document, it is usually preferable that Alembic is This tutorial will provide a full introduction to the theory and usage of this tool. Scripts for a relational database, using SQLAlchemy as the underlying engine. Alembic provides for the creation, management, and invocation of change management