Create a partial model definition of a pydantic model

Sometimes I want to create a partial model definition of a pydantic model. For example, if I want to expose a database model from API, some of the fields I would like to keep in secret, or I just want to expose very few fields in a summary API. I don’t want to write model definition twice. I would like to write something like ModelExposed = partial_model(ModelSource, 'ModelExposed', include=["title", "description"]) So I write a funciton as below to do it, including support of passing list of excluding fields, copying computed fields and validators. Continue reading

psql vs. mysql shell command cheatsheet

MySQL Postgres list databases SHOW DATABASES \l change to a database USE <db_name> \c <db_name> list tables SHOW TABLES \dt describe a table DESC <table_name> \d <table_name> show the create table sql SHOW CREATE TABLE <table_name> pg_dump -st <table_name> <db_name> explain a query EXPLAIN <sql_statement> EXPLAIN <sql_statement> quit shell QUIT \q

Deploy next.js using pm2 cluster mode(and with docker)

We can simply start the Next.js application using next start. However, when facing higher traffic demands in practical use, how can we deploy Next.js using a multi-process approach? We can achieve this using the cluster mode of pm2. The cluster mode is a powerful way of scaling Node.js applications, allowing you to start multiple processes, all listening on the same port. How do we do this? First, we can create a . Continue reading

Use python -m http.server in SSL

python -m http.server is a very convenient command line tool to start an ad-hoc static web server. This tool is very useful when you want to develop small web applications or serve static files. But it does not support SSL. A lot of modern web applications as well as browser features require a secured connection. So I want to wrap http.server in SSL and try making it simple to use. Continue reading

The contextvars and the chain of asyncio tasks in Python

In Python, the contextvars is somehow like thread local, but mostly for coroutines. But will the context itself be kept consistent in a chain of asyncio tasks? Let’s find out. contextvars Let’s have a rough review of the contextvars in Python. The contextvars module provides a way to maintain a context across a chain of function calls, natively supported with asyncio. For example import asyncio import contextvars var = contextvars.ContextVar('var', default={}) async def sub2(): print(f'in sub2, {var. Continue reading

Unix pipe to clipboard with WSL, and in UTF-8

WSL is good, it will be even better if we can pipe stdout directly into Windows host’s clipboard. Just like ./myscript.sh | to-my-clipboard.sh Note that xclip requires X, so it is not an option. From WSL, we have direct access to Windows executables. The easiest method would be using clip.exe: ./myscript.sh | clip.exe The method works fine if you don’t touch CJK characters or emojis. clip.exe didn’t handle the encoding well since the default codepage in Windows is not 65001(UTF-8). Continue reading

Several tips for better working with Python in Excel

After enrolled for Python in Excel preview, now I can type =py( in any Excel cell to write some Python code. Python in Excel doesn’t have detailed documents, only Get Started tutorials, like link 1, link 2, or articles talking about topics like pandas, matplotlib, seaborn, etc., it may confuse you when you want to do some real work in an unfamiliar environment. The article notes several tips from my understanding of Python in Excel. Continue reading