Kev’s Blog – Page 158 – Kev's Development Toolbox

May 19, 2016

Node.js and Mongoose: connection hanging on find()

Following this tutorial to build a simple REST api on Node.js with Express, attempting to retrieve all docs from my MongoDB gave these errors:

2016-05-19T20:10:47.311-0700 [initandlisten] connection accepted from 127.0.0.1:52053 #4 (2 connections now open)

2016-05-19T20:10:47.325-0700 [conn4]  authenticate db: nodetest { authenticate: 1, user: "", nonce: "xxx", key: "xxx" }

2016-05-19T20:10:47.336-0700 [conn4] Failed to authenticate @nodetest with mechanism MONGODB-CR: ProtocolError field missing/wrong type in received authenticate command

Some quick Googling turned up the same error in this post that just suggested authentication was failing because no user was passed. So created a new used with:

db.createUser({user : 'nodetest', pwd: 'passwordhere', roles: ['readWrite', 'nodetest']})

… and problem solved.

May 16, 2016

Update: onscreen keyboard for Raspberry Pi 7″ touchscreen

Quick followup from last week’s post on setting up an onscreen keyboard. I couldn’t find a way of getting an onscreen keyboard, either matchbox-keyboard or florence, to respond on Raspbian’s logon screen. Rather than spend more time on investigating this, I just enabled the logon to desktop in raspi-config, and now logged on, either of the keyboards work as expected, perfectly well.

Florence seems to be the better of the two I tried. Once opened from the menu you can drag it around, or minimize it to a keyboard icon, so you can pop-it open as needed.

If I could get it to work from the logon screen too that would be awesome, but avoiding that issue and once you get to the desktop, it works great.

May 14, 2016

In progress: Setting up an onscreen keyboard for the 7″ touchscreen on the Raspberry Pi

I just received one of these very cool 7″ touchscreens for the Raspberry Pi: https://www.raspberrypi.org/products/raspberry-pi-touch-display/

I have the default logon prompt when my Pi starts up, so first challenge is, how do you logon without a real keyboard attached, without having to disable the logon? There are a number of onscreen keyboards available – based on this thread I installed florence:

sudo apt-get install florence

and then edited /etc/lightdm/lightdm-gtk-greeter.conf adding ~a11y; for the Accessibility icon on the logon screen, and keyboard=florence so it appears in the menu.

The keyboard now appears, but as soon as I press a key it disappears. From this thread, installing at-spi2-core appears to fix the issue:

sudo apt-get install at-spi2-core

This seems to fix the keybaord not disappearing, but not having any luck getting characters to appear in the username/password fields. Still some investigation to do on this one.

April 29, 2016

Booting Raspbian Jessie to a shell prompt

Raspbian Wheezy on the Raspberry Pi used to boot to a shell by default, but on Jessie, the default is to boot in graphical mode to the desktop. You can easily change this with raspi-config, either from the desktop menu using the gui app or raspi-config from the command line. Step by step instructions in this post.