neilmcguigan

# TAG is a Redshift keyword, so we have to create this table ourselves, and quote TAG
# otherwise, you need a custom database class for liquibase
# see https://github.com/liquibase/liquibase-redshift

CREATE TABLE public.databasechangelog (
  ID VARCHAR(255) NOT NULL, 
  AUTHOR VARCHAR(255) NOT NULL, 
  FILENAME VARCHAR(255) NOT NULL, 
  DATEEXECUTED TIMESTAMP WITHOUT TIME ZONE NOT NULL, 
  ORDEREXECUTED INTEGER NOT NULL, 

neilmcguigan

# main.py

@app.middleware("http")
async def set_xhr(request: Request, call_next):
    request.state.is_xhr = "HX-Request" in request.headers
    return await call_next(request)
    
# in your Jinja2 template :

{% if request.state.is_xhr %}

neilmcguigan

"""
A sample app to show how to use optimistic concurrency / optimistic locking in Flask and SQLAlchemy

The trick is to store your entity in session between requests
You need to use Flask-Session, so can serialize your entities properly

Usage:
flask --app optimistic-locking.py run
navigate to http://127.0.0.1:5000/edit/1

neilmcguigan

1. Jinja Macros can return results (but only if `called`):

```
{% macro foo() %}
  hello from foo
  {{ caller({"bar":1}) if caller is defined }}
{% endmacro %}

{% call(result) foo() %}
  {{result.bar}}