Smartxel Media

Using ObjectParameter on an Entity SQL query against the Entity Framework

Amit — Fri, 04 Sep 2009 13:19:47 +0000

I am writing this module to dynamically create Entity SQL query which go against the Entity Framework.
To prevent SQL injection, instead of directly concatenating the string I am passing the values for the where clause using the array of ObjectParameter[].

Since I am dynamically creating the Parameter array in order to create a unique parameter key for every value I used the logic to concatenate the field names and add an integer to it.

So if the field was City, the parameter key would be “City1″
If the field was Address.Phone.HomePhoneNumber, the parameter key would be “AddressPhoneHomePhoneNumber1″. The key doesn’t allow dpts “.”, so have to remove them too.

On one such query I found out that I kept getting an error every time I executed it. The error was the generic ListDictionary error:
“System.ArgumentException : An item with the same key has already been added”

I confirmed and re-confirmed that the parameters I was adding had unique keys and they were all new parameters (sometimes these objects just clone instead ofcreating new). I confirmed that the resulting DbDataRecord had unique rows. After 4 hours of debug and deliberation I finally found out what the problem was.

The ObjectParameter key (name property) allows only 30 characters !!

There is no error if you add a key which is greater than 30 characters in length, it just cuts the key and adds the first 30 characters. So when the keys I was creating got to a length greater than 30 the keys were just getting cut to 30 and were getting added as duplicates !

So if any of you getting the same error while using ObjectParameters bear in mind, keys(name) length = 30 !

AutoScroll in a DataGrid

Amit — Mon, 08 Jun 2009 21:43:29 +0000

This post will address how to AutoScroll to a specific object (row) in the DataGrid and select it.
gridContactsList is of type Microsoft.Windows.Controls.DataGrid

This is a great way of automatically selecting the newest inserted row in the Grid.

Once you know the index of the newly created object and you have added it to the Grid, use the following two lines to AutoScroll and select the row:

gridContactsList.UpdateLayout();
gridContactsList.ScrollIntoView(gridContactsList.Items[index1]);

The method gridContactsList.ScrollIntoView(…) accepts the object that needs to be selected.
This method also has an oeverload that takes the object to be selected and the column.

The most important thing to notice about the AutoScroll and selection is that You have to call the gridContactsList.UpdateLayout(); method before using the ScrollIntoView method. Not doing so will throw a null reference even if the object reference is valid.

High yield dividend investments - MLPs

Amit — Wed, 27 May 2009 01:11:46 +0000

I have been looking for solid dividend investments for some time and stumbled upon what’s known as MLPs (Master Limited Partnerships) about a month ago. I started looking into these and some of these have been on my track list since.

Most of these MLPS have bounced back after dropping to all time lows some months ago and I am keeping on the sidelines right now looking for an entry point. In the meantime, here’s a little info for your perusal.

MLPs don’t pay income taxes and they trade their “investment units” on stock exchanges just like common stocks. According to the Tax Reform Act of 1986 and the Revenue Act of 1987 to qualify for the tax benefit, 90% of the income should come through income through activities relating to natural resources, commodities or real estate. Instead of paying the corporate income tax, the tax liability is passed on to the “unitholders” of the corporation and the income is taxed at the individual’s rate by filing a K-1.

The MLPs give out cash ”distributions” to the investors which from an investors point of view, can be looked into as dividends. Although these are distributions, the taxation governing these distributions is different from how your dividends would be taxed. For more information on taxation you can visit National Association of Publicly Traded Partnerships or Investopedia Article on Discover MLPs.

Most of the MLPs, that I have looked into have a dividend yield of anywhere from 8% to 11% and are Crude or Natural gas pipelne Operators, propane retailers and/or engage in the business of exploration and production of crude oil or natural gas etc.

Some of the MLPs with a high yield for further investigation are:

EEP : Enbridge Energy Partners LP : Latest Dividend Yield : 10.38%

KMP : Kinder Morgan Energy Partners L.P. : Latest Dividend Yield : 8.83%

ETP : Energy Transfer Partners LP : Latest Dividend Yield : 8.98%

ETE : Energy Transfer Equity LP : Latest Dividend Yield : 8.14%

EPD : Enterprise Products Partners LP : Latest Dividend Yield : 8.55%

C# Partial in-code implementation of the Start With, Connect By clause

Amit — Wed, 20 May 2009 17:28:13 +0000

I am working on this project where I had a list of parent - child elements and I had to extract a particular chain of parent - child elements, given the starting child. I am sure lot of developers have written this code. As a natural instinct I started googling for an in-code implementation of Oracle’s START WITH, CONNECT BY clause.

After spending some time searching this, I got nothing. So I implemented this code and thought I will share this out for anyone who is looking for it. This code doesn’t do well with duplicate relationships, so if that is something you want, you are on your own.

initialLink is the initial List.

startingChild is the starting child that you want to start traversing the parent - child link.

extractedLink is the resulting link.

void ExtractParentChild( Dictionary<string, string> initialLink, string startingChild,

Dictionary<string, string> extractedLink )

{

// Traverse the Dictionary to build the parent-child dictionary

foreach (var v in initialLink)

{

if (v.Key.Equals(startingChild))

{

extractedLink.Add(v.Key, v.Value)

ExtractParentChild(initialLink, v.Value, extractedLink);

}// if

} // foreach

}

If you need to stop somewhere before the end of the link is reached you can add the condition around the for loop and return in the if, when the condition is reached.

Expanding short url to original url using Java

Jagdish — Mon, 11 May 2009 00:58:35 +0000

There are plenty of URL shortening services designed for Twitter. Recently, Twitter picked bit.ly as their official URL shortening service. Here is quick Java code to expand short URL to original URL-

                System.out.println(”Short URL: “+ shortURL);
                urlConn = connectURL(shortURL);
                urlConn.getHeaderFields();
                System.out.println(”Original URL: “+ urlConn.getURL());

// connectURL - This function will take a valid url and return a URL object representing the url address.

URLConnection connectURL(String strURL) {
        URLConnection conn =null;
try {
     URL inputURL = new URL(strURL);
     conn = inputURL.openConnection();
            int test = 0;

}catch(MalformedURLException e) {
     System.out.println(”Please input a valid URL”);
}catch(IOException ioe) {
     System.out.println(”Can not connect to the URL”);
}
       return conn;

}

Cheat sheet for Collections in C#

Amit — Tue, 05 May 2009 19:51:52 +0000

Lot of times I see myself going back to the books to check which ‘collection’ would be the best suited for a particular activity I am performing in my code. After doing this several times I thougt it would be great to create a cheat-sheet of all the collections and where they can be used efficiently.

Now that I have had it for several months, I thought I should share it on the world wide web ! So help yourself -

ArrayList:

Simple, resizeable, index-based collection of objects

SortedList:

Sorted collection of name/value pairs of objects

Queue:

First In First Out (FIFO) collection of objects

Stack:

Last In First Out (LIFO) collection of objects

Hashtable:

Collection of name/value pairs of objects that allow retrieval by name or index

BitArray:

Compact collection of boolean values

StringCollection:

Simple collection of resizeable collection of strings

StringDictionary:

Collection of name/value pairs of strings that allow retrieval by name or index

ListDictionary:

Efficient collection to store small lists of objects

HybridDictionary:

Collection that uses ListDictionary for storage when the number of items in the collection is small, and then migrates the items to a Hashtable for large collection

NameValueCollection:

Collection of name/value pairs of strings that allows retrieval by name or index

Just freaking HONK your HORN !

Amit — Tue, 21 Apr 2009 17:29:42 +0000

Yes, this is a vent.

Goes to all those slow moving cows (SMCs) hogging the left lane on a two lane highway. I think these people, who just don’t budge no matter how long a tail they create behind them, are the most important reason why we have incidents of highway-rage. And the second reason: People stuck behind these SMCs who don’t HONK their freaking horns!

I have observed (especially here in the mid-west) people think it is improper and impolite to honk their horns at other vehicles, no matter how the person infront of you is driving. So if a slow moving vehicle happens to get infront of you, instead of HONKing the horn and letting the person know about your dissatisfaction about them hogging the left (and hence the fast) lane, people keep their anger bottled within and when they blow their corks off, follow the person to his (or her) house and confront him (or her) or take their guns to the highway and shoot.

So here’s a plea, next time you see yourself stuck behind a slow moving cow, save a life and just freaking HONK your HORN !

Microsoft Office Lab vision 2019

Jagdish — Mon, 02 Mar 2009 00:59:09 +0000

Home Weatherization

Amit — Tue, 10 Feb 2009 22:21:29 +0000

January 27, 2009: “The federal stimulus plan now being debated in Washington, D.C., sets aside $6 billion to weatherize low-income homes.”

Start at home. The best way to cut your energy costs and become efficient is to cut your (energy) losses right where they are spent the most, at your own house.

Very straightforward practices like, Insulating your home, can cut more than 40% of your utility bill.
Choosing ENERGY STAR appliances, have a professional seal air leaks, seal ducts to reduce leakage etc. all contribute to reducing the utility bills

With the new homes on a backlog and utility bills going through the roof, I believe home weatherization is the industry that will see two or three fold increase in the next coming years.

To do list : What public companies are in this business right now?

Lazy Portfolios: Keep it simple

Amit — Tue, 30 Dec 2008 22:07:47 +0000

Paul B. Farrell’s Lazy Portfolios

Full context of the post can be found at: http://www.marketwatch.com/lazyportfolio

The gist of the matter is “keep it simple”. No reason to watch the market every second of the day, simple buy and hold portfolios based on index funds that spend minimum amount of your invested money in expenses.

Personally, I like the Vanguard index funds and go with a simple portfolio spread between:

1. US Based equity - 40%

2. International - 30%

3. Small Cap - 10%

4. Bonds and Cash - 20%

Next food for thought: A Portfolio based on ETFs