Technical writing about Python & Django

I have some slow running, low priority Celery tasks that I don’t want holding up more important tasks. I learnt how to configure Celery tasks, and queues, to support message priorities. Note, the project in question uses Django, Celery, and RabbitMQ. Firstly, I needed to decide on my priority values. Whilst RabbitMQ supports priorities between 1 and 255, their docs highly recommend using values between 1 and 5. It is important to know that higher priority values require more CPU and memory resources, since RabbitMQ needs to internally maintain a sub-queue for each priority from 1, up to the maximum value configured for a given queue....

I recently ran into this error uploading images to AWS S3 using the boto3 package. Parameter validation failed: Non ascii characters found in S3 metadata for key “filename”, value: “ACME™ Anvil.jpg”. S3 metadata can only contain ASCII characters. The character in question was ™. Here’s a simplified example of the code. filename = "ACME™ Anvil.jpg" metadata: dict[str, str] = { "filename": filename, } client.upload_fileobj( Fileobj=..., Bucket=..., Key=..., ExtraArgs={"Metadata": metadata} ) I wanted to preserve the original filename, so I learnt to use backslashreplace when encoding the filename to ASCII....

Let’s say I have the following Django model. from django.db import models class User(models.Model): name = models.CharField(blank=True) And I want to filter those like so. users = User.objects.filter(name__istartswith="John") That would perform the following query. SELECT "data_user"."id", "data_user"."name" FROM "data_user" WHERE UPPER("data_user"."name"::text) LIKE UPPER('John%') I can improve the performance of that query by adding the following index to the model. To complement the use of UPPER() in the query I can use the Upper() function for the index’s expression....