Simulating a foreign key constraint in ActiveRecord (Ruby on Rails)

eddiewould (Eddie) — Thu, 01 Feb 2007 00:55:54 GMT

Say for example we have products and a business rule that every product must have a category. Before ActiveRecord we would have done this with a NOT NULL foreign key constraint at the database level.

It wasn't entirely obvious (to me) how to achieve this in an ActiveRecord model - you need *both* of the following two lines:



  validates_presence_of :category, :message => " must be specified" 

  validates_associated :category

Hope this helps someone.

Xorg.conf file for Acer C300 Notebook/Tablet (Dual head support with 1280x1024)

eddiewould (Eddie) — Fri, 05 Jan 2007 11:37:06 GMT

Supports 1280x1024 on a second screen as well as 1024x768 on main LCD. The following two lines are particularly important:
Option "DDC" "0"
Option "VBERestore" "0"
Without them, the setup breaks unless you wait for X to start before plugging in the external monitor.



Section "Device"

       Identifier  "Videocard0"

       Driver      "i810"

       VendorName  "Videocard vendor"

       BoardName   "Intel Corporation 82852/855GM Integrated Graphics Device"

       BusID       "PCI:0:2:0"

       Screen      0

      Option      "MonitorLayout" "CRT,LFP"

       Option      "AGPMode"      "0"

       VideoRam    32768

       Option	  "DDC"		"0"

       Option	  "VBERestore"  "0"

EndSection

Section "Device"

       Identifier  "Videocard1"

       Driver      "i810"

       VendorName  "Videocard vendor"

       BoardName   "Intel Corporation 82852/855GM Integrated Graphics Device"

       BusID       "PCI:0:2:0"

       Screen      1

       Option      "MonitorLayout" "CRT,LFP"

       Option      "AGPMode"      "0"

       VideoRam    32768

       Option	  "DDC"		"0"

       Option	  "VBERestore"  "0"

EndSection

Section "Monitor"

       Identifier  "Laptop LCD"

       Option      "DPMS"

       HorizSync   30-81	

       VertRefresh 56-75

EndSection

Section "Monitor"

       Identifier  "Desktop CRT"

       Option      "DPMS"

       HorizSync   30-81

       VertRefresh 56-75

EndSection

Section "Screen"

         Identifier      "Screen0"

         Device           "Videocard0"

         Monitor           "Laptop LCD"

         DefaultDepth      24

         SubSection "Display"

               Depth           24

               Modes           "1024x768"

         EndSubSection

EndSection

Section "Screen"

         Identifier          "Screen1"

         Device                "Videocard1"

         Monitor               "Desktop CRT"

         DefaultDepth      24

         SubSection "Display"

               Depth           24

               Modes           "1280x1024"

         EndSubSection

EndSection

Section "ServerLayout"

       Identifier      "DefaultLayout"

       Screen          0 "Screen0" 0 0

       Screen          1 "Screen1" LeftOf "Screen0"

       InputDevice	"Generic Keyboard"

       InputDevice	"Configured Mouse"

       InputDevice	"Synaptics Touchpad"	

       Option          "Xinerama"

       Option          "Clone"    "Off"

EndSection



Section "DRI"

	Mode 0666

EndSection

Create an regexp (Regular expression) from an array of Strings

eddiewould (Eddie) — Tue, 19 Dec 2006 12:36:07 GMT

// description of your code here
Create a DNF regular expression from an array of strings even if they have special characters.



Regexp.new(array.collect{|string| Regexp.escape(string)}.join("|"))

DZone Snippets: Eddiewould's Code Snippets

Simulating a foreign key constraint in ActiveRecord (Ruby on Rails)

Xorg.conf file for Acer C300 Notebook/Tablet (Dual head support with 1280x1024)

Create an regexp (Regular expression) from an array of Strings