Code Samples

sorting rails view with will_paginate plugin

2010-03-23T08:32:00.000-07:00

This solution for sorting data on rails index actions does NOT use ajax. Sometimes sorting with ajax is nice but often it is not actually as user friendly; breaking the browser back button, etc...

Disclaimer 1: this code is probably using all kinds of ruby anti-patterns :) - but it is a very simple implementation and so I just went with it...

Disclaimer 2: the title of the post might be a little miss leading as you can use this with or without the will_paginate plugin. In my case I am using it with the will_paginate plugin - and I highly recommend it!

put this file in your rails lib directory /lib/sort_index.rb

in your controller code, set up the SortIndex::Config (you can have more than one if you have multiple actions that need to support sorting

then in your view code render your table headers using the sort object

Does not support the following:

additional attributes on the anchor tags
additional attributes on the table header tags
additional query string parameters - might add this later, would be nice for search results

Ruby Http Get with Net::HTTP

2010-01-06T10:03:00.000-08:00

Resources

Ruby Regex to remove script tags

2010-01-06T09:56:00.000-08:00

Resources

Attribute "target" exists, but can not be used for this element.

2009-09-25T07:58:00.000-07:00

These days I am all about valid xhtml and was surprised to receive this validation error when using the target attribute on an anchor tag.

Attribute "target" exists, but can not be used for this element.

I found a nice work around that does not involve window.open, using jquery we can hack the attribute on 'after' the dom has loaded.

Now instead of target='_blank' you can just use class='target-blank', if the browser does not support javascript it will not open in a new window but the link will still work - and we have our valid xhtml.

Resources

Ajax error handling with ruby on rails and jquery

2009-08-21T13:09:00.000-07:00

This sample is just a slight modification of this post 'Handling AJAX errors and displaying friendly error messages to users'. Basically I wanted to maintain the existing rails error handling for non-ajax pages and then have good handling for errors in both development and production mode; i.e. get errors in the browser when in development mode and show a nice message when in production mode.

Modify /app/controllers/application.rb; add the rescue_from macro and the handler_exception method

Then add a global javascript method for presenting the errors; most likely in application.js

Then a sample usage, jquery making an ajax post to a rails controller action

in development mode the error message is returned in an easier to read view in the firebug console and an alert message is presented that has a truncated version of the error

in production mode just a friendly error message.

Resources

Handling AJAX errors and displaying friendly error messages to users
Rails source code rescue.rb
Rails views source on your install lib/action_controller/templates/rescues
jquery ajax

Get list of MSSQL jobs that are currently running

2009-08-04T13:54:00.000-07:00

The following sql statement will return information about the currently executing MSSQL jobs.

Run it against the msdb database

Resources

PGError: ERROR: invalid byte sequence for encoding "UTF8": 0xa7 (ActiveRecord::StatementInvalid)

2009-04-23T21:31:00.000-07:00

Working on a rails application and have decided to make the switch from MySql to Postgresql; ran into a few minor issues along the way and one really annoying and unexpected issue

PGError: ERROR: invalid byte sequence for encoding "UTF8": 0xa7 (ActiveRecord::StatementInvalid)
HINT: This error can also happen if the byte sequence does not match the encoding expected by the server, which is controlled by "client_encoding".

The above error was being generated when I was trying to save model objects that had their string and text attributes assigned from data that had been scrapped using http with scRUBYt. After searching on Google the only 'work-around' I found was to use base64 encode and decode when reading and writing to these model attributes / database columns

Given the following migration

Our model before and then after applying the work-around

Resources

UPDATE: NAnt build with TFS changeset as revision number

2009-04-09T11:51:00.000-07:00

this is a small revision to a previous post NAnt build with TFS changeset as revision number

apparently there is a limitation on the size of the number used in each segment of a .net assembly version so this is a slight update to the c# code that gets the latest changeset from TFS - changes start at "if(latestChangsetId > 65534)"

public static void ScriptMain(Project project) { project.Log(Level.Info, "Connect to " + project.Properties["tfs.server"]); TeamFoundationServer tfs = new TeamFoundationServer(project.Properties["tfs.server"]); // Get a reference to Version Control. Type type = typeof(VersionControlServer); VersionControlServer versionControl = (VersionControlServer)tfs.GetService(type); project.Log(Level.Info, "get changesetId for " + project.Properties["tfs.fullpath"]); IEnumerable changeSets = versionControl.QueryHistory(project.Properties["tfs.fullpath"], VersionSpec.Latest, 0, RecursionType.Full, null, null, null, 1, true, false); int latestChangesetId = 0; // there is only one foreach(Changeset c in changeSets) { latestChangesetId = c.ChangesetId; } string revision = String.Empty; if(latestChangsetId > 65534) { // use the last 4 numbers only revision = latestChangesetId.ToString().Substring(latestChangesetId.ToString().Length - 4, 4); } else { revision = latestChangesetId.ToString(); } project.Log(Level.Info, "ChangesetId is " + latestChangesetId.ToString()); project.Log(Level.Info, "Revision will be " + revision); project.Properties["project.version.revision"] = revision; }

Get Filenames and Database names from MSSQL

2009-03-26T09:15:00.001-07:00

I was doing some clean up on one of our database servers; we have many databases created with backup/restore for testing purposes I was checking for the largest ldf files and making sure those databases were in simple mode and then shirking the data files, there were a few files I could not match to the databases because the mdf and ldf file names were different from the actual database file name - found the following queries using a few google searches

use jquery to disable a button when clicked

2009-02-16T14:57:00.000-08:00

jquery is such a great javascript library, the more I use it the more I like it

NOTE: the above code snippets are untested - cut, pasted and modified from real code that was tested (and worked!)

Calling rake tasks from another rake task

2008-11-01T08:33:00.000-07:00

This turns out to be pretty straight forward, but was not obvious

A rake task to rebuild the development database

Resources

MSSQL drop and re-add constraints

2008-05-18T07:54:00.001-07:00

One of the guys at work hooked me up with this code - quite useful if you want to do a bunch of data inserts but don't want to worry about the order you apply the inserts because of foreign key constraints

Before performing data actions:

After performing data actions:

Thanks to ET for this code bit!

Rolling Over Rails production.log file

2008-05-10T13:25:00.000-07:00

Just came across this on a rails forum (post by Freezzo), rails production.log files can grow very large - but no chron job required - this is very handy.

where 'daily' can be 'daily' to 'weekly', 'monthly', '5mb', etc...

NAnt build with TFS changeset as revision number

2008-04-20T15:08:00.001-07:00

This code sample is a nant script that

deletes the CommonAssembly.cs file (linked to all projects)

uses the nant asminfo task to recreate the CommonAssembly.cs file, but after we query TFS for the changeset (revision) number which is used in the version number

build the solution in release mode using the ide.exe (there are other - better ways, but this one works)

xcopy files to C:\temp\{app} and clean up all the source files

basically I just put together a few bits that I found on other blogs (should have saved the urls - doh!), most were related to using svn for source control and then I added in the code block for the c# stuff to query TFS.

A quick note about the linked CommonAssembly.cs file, visual studio has an option when you are adding an existing file to a project to select 'linked', click the arrow on the 'Add' button when you select your existing file

what this script does not do - get latest from TFS, I usually do that part manually or from ccnet

the c# bit that goes in the nant script block above

public static void ScriptMain(Project project) { project.Log(Level.Info, "Connect to " + project.Properties["tfs.server"]); TeamFoundationServer tfs = new TeamFoundationServer(project.Properties["tfs.server"]); // Get a reference to Version Control. Type type = typeof(VersionControlServer); VersionControlServer versionControl = (VersionControlServer)tfs.GetService(type); project.Log(Level.Info, "get changesetId for " + project.Properties["tfs.fullpath"]); IEnumerable changeSets = versionControl.QueryHistory(project.Properties["tfs.fullpath"], VersionSpec.Latest, 0, RecursionType.Full, null, null, null, 1, true, false); int latestChangesetId = 0; // there is only one foreach(Changeset c in changeSets) { latestChangesetId = c.ChangesetId; } project.Log(Level.Info, "ChangesetId is " + latestChangesetId.ToString()); project.Properties["project.version.revision"] = latestChangesetId.ToString(); }

nant is awesome!

Rhino.Mocks - the basics

2008-02-16T09:05:00.000-08:00

Started using Rhino.Mocks recently (Awesome!!!) - just wanted to list a few of the basics; the official Rhino Mocks Documentation is very good and available here. These examples are a bit rough, they have not been compiled; there may be typos.

using

using Rhino.Mocks;

The mock repository

Mock a call to the db

Ignore any arguments

mock a method that returns void

Handle multiple calls to the same method

Partial Mock

Rails RJS and newline characters

2007-10-18T19:17:00.000-07:00

ok this one really got me, I was generating a javascript alert from the server via an rjs file, i.e.

# rjs render a javascript alert on the client
page.alert 'Errors\nError 1\nError 2'

and it kept on printing my error message as Errors\nError message 1\nError message2 - note that the newline characters were being escaped and rendered literally

I found this informative post which lead me to change my code from using single quotes to using double quotes - nasty.

# this one will output the newlines in the javascript alert message
page.alert "Errors\nError 1\nError 2"

here is the final code, looping through each error on the model object (product in this case) and outputing a newline on the javascript alert for each error

# rjs file
page.alert "#{get_message_for_show_server_error}"
# helper file
def get_message_for_show_server_error
__s = "Errors "
__@product.errors.full_messages.each do error
____s = s + "\n" + error.to_s
__end
__return s
end

Ruby Notes - part 1 - dynamic object creation

2007-09-01T10:37:00.000-07:00

I am starting to learn Ruby and Rails (just for fun) - took awhile to find a good example of creating an object at runtime given a string representing the objects name; finally came across this post http://www.ruby-forum.com/topic/96222;

in theses 2 examples - given an ActiveRecord object 'Project' and a database table named 'projects', invoke the Project and execute some methods on it

# using eval
def test_dynamic_invoke_with_eval
__object_name = "Project"
__o = eval(object_name)

__p "object name is '" + o.to_s + "'"
__p "object table name is '" + o.table_name + "'"
end

# using Object.const_get
def test_dynamic_invoke_with_object_const_get
__object_name = "Project"
__o = Object.const_get(object_name)

__p "object name is '" + o.to_s + "'"
__p "object table name is '" + o.table_name + "'"
end

Check the ruby forum link above as well - the last entry posted by 'unknown (Guest)'; this is probably the true ruby way to do it? extend the String object with a helper method so you can turn any string into an object? code from that post

# extend String
class String
__def to_class
___Object.const_get(self)
__end__
end

A client side (javascript) confirm box with ASP.NET

2007-02-11T12:09:00.000-08:00

The following code sample illustrates a client side (javascript) confirm box in use with an aspx button, this presents the end user with a dialog box asking ''are you sure you want to submit this form?', it gives the user two options 'Ok' and 'Cancel', clicking ok will submit the form, clicking cancel will not

This sample code uses 4 variations;

TestButton1 - a standard html input type 'button', which submits the page using hand coded js
TestButton2 - a standard html input type 'submit', it has the default behaviour of submitting the form
TestButton3 - an asp:button with the OnClientClick (rendered as onclick) declared in the mark up
TestButton4 - an asp:button with the onclick defined in the code behind or c#

The aspx page markup - JavaScriptConfirm.aspx


<%@ Page 
  Language="C#" 
  AutoEventWireup="true" 
  CodeBehind="JavaScriptConfirm.aspx.cs" 
  Inherits="SandboxOne.JavaScriptConfirm" 
%>
<!DOCTYPE...>
<html>
<head runat="server">
    <title>Javascript Confirm</title>
    <script language="javascript" type="text/javascript">
    function AreYouSure()
    {
        return confirm('are you sure you want to submit this form?');
    }
    </script>
</head>
<body>
<form id="form1" runat="server">
    <input id="TestButton1"
            type="button"
            onclick="if(AreYouSure()) { document.forms[0].submit(); }"
            value="A regular html 'button' button"
    />
    <input id="TestButton2"
            type="submit"
            onclick="return AreYouSure();"
            value="A regular html 'submit' button"
    />
    <asp:Button ID="TestButton3"
                OnClientClick="return AreYouSure();"
                OnClick="InvokeServerSideMethod"
                Text="A asp button"
                runat="server"
    />
    <asp:Button ID="TestButton4"
                OnClick="InvokeServerSideMethod"
                Text="A asp button c# wired OnClientClick"
                runat="server"
    />
</form>
</body>
</html>

The c# 'code-behind'


public partial class JavaScriptConfirm : System.Web.UI.Page
{
    protected void Page_Load(object sender, EventArgs e)
    {
        // wire the client side onclick to TestButton4
        this.TestButton4.Attributes.Add("onclick", "return AreYouSure();");

        if(Page.IsPostBack)
        {
            Response.Write
            (
                String.Format("Page_Load, IsPostBack: {0}
", DateTime.Now.ToLongTimeString())
            );
        }
    }

    // the server side 'event' kicked off when asp:button is clicked
    protected void InvokeServerSideMethod(object sender, EventArgs e)
    {
        Response.Write
        (
            String.Format("InvokeServerSideMethod, E: {0}
", DateTime.Now.ToLongTimeString())
        );
    }
}

The 'key' here is the return in the onclick method; the javascript confirm will return true if 'Ok' is clicked and false if 'Cancel' is clicked, we must return this value from our buttons onclick event so that the form will not generate an HTTP POST (or PostBack if you like)

if you do not include the return statement in the onclick the form will post back regardless of which button is clicked 'Ok' or 'Cancel'; for instance you do NOT want to do this

 onclick="AreYouSure();"

but instead do this

 onclick="return AreYouSure();"

Generate a Guid from MSSQL

2007-02-11T09:05:00.000-08:00

Really simple...

SELECT NEWID()

This returns a MSSQL datatype of uniqueidentifier
read more here - http://msdn2.microsoft.com/en-us/library/aa276822(SQL.80).aspx

This blog is just for the code samples

2007-02-11T08:54:00.000-08:00

my real blog is at http://house9.blogspot.com/

there really is not anything that interesting there either...