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# file libs/dbutil.py

from itertools import *
from django.db import connection

def query_to_dicts(query_string, *query_args):
    cursor = connection.cursor()
    cursor.execute(query_string, query_args)
    col_names = [desc[0] for desc in cursor.description]
    while True:

maxivak

from django.db import connection, transaction

cursor = connection.cursor()

cursor.execute("UPDATE yourtablename SET field1=value1, .. WHERE .. ")


transaction.set_dirty()        
transaction.commit()

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  def resize_nocrop_noscale(image, w,h)
    w_original = image[:width].to_f
    h_original = image[:height].to_f

    if w_original < w && h_original < h
      return image
    end

    # resize
    image.resize("#{w}x#{h}")

maxivak

require 'mysql2'
 
    db = Mysql2::Client.new(:host => 'localhost', :username => 'root', :password=> 'password', :database => 'db_name'   )
 
    res = db.query("select * from users")
    res.each do |row|
      col1 = row['id']
      col2 = row['email']
 
      ..

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# in controller

# for local files
send_file '/path/to/file', :type => 'image/jpeg', :disposition => 'attachment'

# for remote files
require 'open-uri'
url = 'http://someserver.com/path/../filename.jpg'
data = open(url).read
send_data data, :disposition => 'attachment', :filename=>"photo.jpg"

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# 1. connection.select_values or connection.select_all

ids = ActiveRecord::Base.connection.select_values("select id from users WHERE ...")

# array of integers
# ["1", "2", "5", "6", "7", "8", "3", "10", "11", "9"]

# return hashes without model
sql = "sql query"
rows = User.connection.select_all(sql.squish!)

maxivak

# 1. connection.select_values or connection.select_all

ids = ActiveRecord::Base.connection.select_values("select id from users WHERE ...")

# array of integers
# ["1", "2", "5", "6", "7", "8", "3", "10", "11", "9"]

# return hashes without model
sql = "sql query"
rows = User.connection.select_all(sql.squish!)

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Rails assets CDN

# serve all assets from CDN  server
config.action_controller.asset_host = 'http://cdn.mydomain.com'

#or if your files in a folder on CDN server
config.action_controller.asset_host = 'http://cdn.mydomain.com/myfolder'

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Rails custom error pages

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#!/usr/bin/env ruby
# put in /etc/munin/plugins and restart munin-node
# by Dan Manges, http://www.dcmanges.com/blog/rails-application-visualization-with-munin
# NOTE: you might need to add munin to allow passwordless sudo for passenger-memory-stats 
 
def output_config
  puts <<-END
graph_category App
graph_title Passenger memory stats 
graph_vlabel count