mongo_orm Exception: missing bson key: publish_acl (Exception)

By Maximilian Batz | 2019-05-10

When you extend your field definitions in the mongo_orm document classes, specifically with embedded documents, you might run into the following runtime (!) error: Exception: missing bson key: <name> (Exception) This is not an error in your code – your code is raising, because the database structure is not as it expects it to be!…

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Introduction to the SNAP protocol

By Maximilian Batz | 2019-04-23

Introduction S.N.A.P. is a protocol for communication between several connected hosts. It provides: · addressing · flags · ack/nak request · error detection (different error detection methods available) It can be run over different media, including RS485. It is optimized for a small footprint (limited computing, memory resources), but scaleable depending upon your needs. Basically,…

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Elektronik-Gehäuse & Platinenabmessungen Standards

By Maximilian Batz | 2019-04-20

Abmessungen Raspberry Pi Ein Raspberry Pi 3B+ hat, als Vergleich, die Abmessungen: 85 mm x 56 mm für die Basisplatine. (USB & LAN, sowie andere Stecker ragen teilweise über die Platine hinaus). Hutschiene / DIN-Schiene Hutschiene: TS35, U-förmiges Profil. Standarisierte Befestigungsschiene für Gehäuse, Racks, Schaltschränke, u.s.w. Sie wird vielfach in der Industrie eingesetzt. Einer der…

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Packaging Python projects for Debian / Raspbian with dh-virtualenv

By Maximilian Batz | 2019-04-19

This article aims to explain some things to developers which don’t use Python a lot, and might struggle with some of the concepts otherwise. I highly recommend the lecture of the following article as an introduction to the concepts discussed here: https://www.dabapps.com/blog/introduction-to-pip-and-virtualenv-python/ pypi.org pypi.org is an official repository of software for the Python programming language.…

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mongo_orm custom name for collection

By Maximilian Batz | 2019-04-17

mongo_orm will automatically determine the name for your collection by using the Module and Class name, and appending an “s”. In cases where you want to name your collection, you can simply do this: class PapiTest < Mongo::ORM::Document     collection_name “Buster”     field test : String end get “/” do     pt = PapiTest.new     pt.test = “I want…

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Avahi how to assign several .local names to same IP

By Maximilian Batz | 2019-04-10

In some situations you would like to access the same computer / IP using different .local names. This is possible using the Avahi daemon. The following is written for Ubuntu 18.04 Bionic Beaver. Install Avahi apt install avahi-daemon avahi-utils Avahi automatically adds your computer’s hostname to the .local Domain. For instance, my computer is called…

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Creating a Raspbian repository

By Maximilian Batz | 2019-04-03

If you want to host your own Raspbian repository, this article is for you. A Raspbian repository consists of a special directory structure on a webserver. The files, including the packages, are all static – therefore this repository could also simply be hosted on an Amazon S3 instance, for example. The sources.list entry in Raspbian…

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Cancel datafeedwatch subscription / Datafeedwatch kündigen

By Maximilian Batz | 2019-02-11

DataFeedWatch is a very useful tool for generating feeds from your online shop into a variety of targets (e.g. eBay MIP, Amazon Marketplace, Geizhals, other price comparison engines). However some time you may want to cancel your subscription. The link for it is quite hidden. Here’s the way to do it: click on Account (the…

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Instructions for adding a user to a mongo database for mongo_orm

By Maximilian Batz | 2019-02-09

You don’t want your web application to access the database using your database admin user. Additionally you want it to access only one specific database – maybe you have additional databases running in your mongo instance. Prerequisites: mongo_orm expects the database configuration as environment variables or as a file config/database.yml in your project. The config/database.yml…

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