Exception in thread "main" java.lang.NoClassDefFoundError - Java

Got this error when I was missing a library that came with the build.

If you’re getting this error, you may need to move the lib folder from your build directory into the folder of your JAR file.

How To Use Endpoint Parameter - Flask-Admin

You can access the endpoint parameter by using self.endpoint.

class displayResults(BaseView):
    @expose('/',methods=('GET','POST'))
    def index(self):
        print self.endpoint

admin.add_view(displayResults(name='test', endpoint='test2'))

That will print “test2”.

UndefinedError: 'admin_base_template' is undefined - Flask Admin

This happens when you try to render a template like this:

return render_template('admin/upload.html')

You need to use self.render instead:

return self.render('admin/upload.html')

Enable UART2 On BeagleBone Black for RS232 Cape

1. Use this script to ensure UART2 is enabled in the device tree: https://github.com/victorporof/BeagleBone-SPI-UART
2. Enable ttyO1 it in the firmware using this guide (makes the device appear): http://www.element14.com/community/blogs/mirandasoft/2013/07/30/beaglebone-black-rapid-activation-of-ttyo1-ttyo2-ttyo4-and-ttyo5
3. Put a paperclip into the RS232 port like in the picture on this page: http://sensorsblog.com/serial-communications/rs232loopbacktest/
4. echo hello > /dev/ttyO1
5. cat /dev/ttyO1

Clustering With Leaflet

Clustering With Leaflet

The Z Layout

I’m definitely going to use this technique on my next business site: Understanding the Z-Layout in Web Design

Two Column Match - Flask + HandsOnTable

I’m getting more comfortable with Flask, so I decided to experiment with Google App Engine + Flask + HandsOnTable.

I made a small app that takes the contents of the 2nd column and matches it to the rows of the first column. I’ve found myself doing this a few times by manually creating two python lists and comparing them in IDLE, so it saves me that work.

Here’s the code: https://github.com/pawl/2ColumnMatch

SQLalchemy - Simple Select Query

from sqlalchemy import create_engine, MetaData, Table

engine = create_engine('sqlite:///cars.db', echo=False)
metadata = MetaData(bind=engine)

table = Table('cars', metadata)
stmt = table.select()
for row in stmt.execute():
    print row

Entity-Attribute-Value - Dynamic Database Columns

This page has a great example of when to use the Entity-Attribute-Value data model: http://stackoverflow.com/questions/7933596/django-dynamic-model-fields

I’m planning to use it for an application I’m making which has user defined fields.

SHOW COLUMNS or Get Column Names From SQLalchemy SELECT Query

http://stackoverflow.com/questions/8947616/python-sqlalchemy-get-column-names-dynamically

Rob Wouter’s answer really helped me out:

You can either find the columns by calling result.keys() or you can access them through calling v.keys() inside the for loop. Here’s an example using items():

for v in result:
    for column, value in v.items():
        print('{0}: {1}'.format(column, value))