C# Discussion Boards - CodeProject

HimalR82-Aug-12 4:28

2-Aug-12 4:28

Hi im currently developing an web based application, i have installed an ajax toolkit and would like to be notified when someone inserts or updates a field in the database on my website.(Basically push technology or feeds)

Im hoping to have a "new customer added" on my website so everyone that views the page knows a new customer has been added.

Im currently using sql server 2008 R2 management studio and c# (asp.net).

Thanks guys.please reply asap.

Regards
H Laugh | :laugh:

Re: sql table change notifications

BobJanova2-Aug-12 4:40

BobJanova

2-Aug-12 4:40

Any 'push technology' on a website is a fake. HTTP doesn't support push. Therefore you should pick the fake which puts the least stress on your system for the desired effect. Also, databases don't really support events very well, so pushing notifications from there is not easy, and since you have to store them somewhere waiting for an AJAX request, it's not useful either.

I'm assuming that you record the date of registration with a customer. I further assume that you have some kind of ping mechanism in your web app (i.e. at some interval you make an AJAX request to a server script which checks for updates); if not, first you should set that up (a setInterval call to send a request).

So what you want to do is:

store the last time a user checked for this type of update. This is probably in the session, as you don't usually want to spam a user with 100 'new customer' notifications when they log on, but for some updates (e.g. PMs) you do want to put up the blinking 'You have 100 new PMs' notice then. If it's persistent, you want to have a database table (lastuserupdates or something like that) to record this.
in your ping response server script, you want to get the relevant updates, i.e.
select count(*) from customer where date>@session.LastCheckedCustomerUpdates
... and send that information as part of the ping response. JSON is common for this, or you can use a simple text format. E.g. updates = {newcustomers:1}. Obviously, if you want more than just a number notification you can select other data too.
That script should also update the last-checked-time so the customer isn't reported as new the next time as well.
The JavaScript AJAX response handler for the ping should do something intelligent with the information. A simple thing is to add news items to a scrolling ticker type of display.

Finding value in a list

Nathaniel Sumaya1-Aug-12 23:33

Nathaniel Sumaya

1-Aug-12 23:33

public Country(string cAbs, string cName)
{
    this._country = cName;
    this._abs = cAbs;
}

private void btnOk_Click(object sender, EventArgs e)
        {
            Country myCountry = new Country();

            CountryList countries = new CountryList();

            countries.Add(new Country("AE", "United Arab Emirates"));
            countries.Add(new Country("AF", "Afghanistan"));
            countries.Add(new Country("AQ", "Antarctica"));
            countries.Add(new Country("AR", "Argentina"));
            countries.Add(new Country("AT", "Austria"));
            countries.Add(new Country("AU", "Australia"));
            countries.Add(new Country("BD", "Bangladesh"));
            countries.Add(new Country("BE", "Belgium"));
            countries.Add(new Country("BR", "Brazil"));
            countries.Add(new Country("BS", "Bahamas"));
            countries.Add(new Country("CA", "Canada"));
            countries.Add(new Country("CH", "Switzerland"));
            countries.Add(new Country("CL", "Chilie"));
            countries.Add(new Country("CM", "Cameroon"));
            countries.Add(new Country("CL", "Chilie"));
            countries.Add(new Country("CN", "China"));
            countries.Add(new Country("CO", "Columbia"));
            countries.Add(new Country("CR", "Costa Rica"));
            countries.Add(new Country("DK", "Denmark"));
            countries.Add(new Country("DM", "Dominica"));
            countries.Add(new Country("DO", "Domican Republic"));
            countries.Add(new Country("EC", "Ecuador"));
            countries.Add(new Country("EE", "Estonia"));
            countries.Add(new Country("EG", "Egypt"));
            countries.Add(new Country("ES", "Spain"));
            countries.Add(new Country("ET", "Ethiopia"));
            countries.Add(new Country("EU", "European Union"));

            //CountryList country = countries.Where(f=> f.CountryAbreviation == this.textBox1.Text)  

            //Country country = countries.Where(f => f.CountryAbreviation == this.textBox1.Text).OrderByDescending(f => f.CountryAbreviation).FirstOrDefault();
                       
        }

Question:

1. How to find the a country in a list?

Re: Finding value in a list

Ed Hill _5_1-Aug-12 23:44

Ed Hill _5_

1-Aug-12 23:44

Country foundCountry = CountryList.FirstOrDefault(c=>c.CountryAbreviation == this.textBox1.Text);
if (foundCountry==null)
{
//invalid search text
}

Have you considered Using a

Dictionary<String, Country>

that would allow

CountryList.ContainsKey(this.textBox1.Text)

and

Country foundCountry = CountryList[this.textBox1.Text]

What you want to do will depend on if you have more than one item with the same abreviation

Re: Finding value in a list

AmitGajjar2-Aug-12 2:42

AmitGajjar

2-Aug-12 2:42

Just want to point out

Quote:
Country foundCountry = CountryList[this.textBox1.Text]

in above code there may be chances of KeyNotFound Exception[^]

Anyway 5+

Thanks
-Amit Gajjar (MinterProject)

Re: Finding value in a list

Ed Hill _5_2-Aug-12 3:26

Ed Hill _5_

2-Aug-12 3:26

thanks, i should have been a little more clear, the CountryList.ContainsKey check should be called first before attempting access via CountryList[this.textBox1.Text].

Thanks for the 5

Re: Finding value in a list

BobJanova2-Aug-12 4:29

BobJanova

2-Aug-12 4:29

You can use TryGetValue (in recent .Net, but if you're already suggesting Linq then it is also available) which will do the contains check and the lookup in a single call.

Country c;
if(dict.TryGetValue(text, ref c)){
 // do stuff here
} // otherwise, it wasn't in the dict

Re: Finding value in a list

Ramesh Muthiah3-Aug-12 0:47

Ramesh Muthiah

3-Aug-12 0:47

IEnumerable<country> filteredCountry = countries.Where(f => f.GetAbbreviation == "EG");

if (filteredCountry != null)
{
Country countryOne = filteredCountry.First();

}
try out the above code !!!! Smile | :)

Re: Finding value in a list

Ed Hill _5_3-Aug-12 0:59

Ed Hill _5_

3-Aug-12 0:59

if (filteredCountry != null)

this will not ever be null as it is assigned on the line above, but it may contain no results if there are no matches, causing First to return an InvalidOperationException.
FirstOrDefault then a null check would be safer

Re: Finding value in a list

Christian Amado6-Aug-12 10:39

Christian Amado

6-Aug-12 10:39

countries.FirstOrDefault(q=>q.cName == country_search);

Regards

Christian Amado
MCITP | MCTS | MOS | MTA
Olimpia ☆ ★★★

Please mark as answer, if it helps.

setting the source of a bitmap image in C#

Xarzu1-Aug-12 18:39

Xarzu

1-Aug-12 18:39

In a silverlight app, I have a BitmapImage defined as System.Windows.Media.Imaging.BitmapImage and it as a method called "SetSource" where I can set the source like this:

BitmapImage bitmap = new BitmapImage();
System.IO.Stream stream = _scene.GetStream();
if (stream == null) return;
bitmap.SetSource(stream);

In a WPF application I have also have a
Bitmap image defined as System.Windows.Media.Imaging.BitmapImage buty there is no SetSource method. How do I set the source in a WPF app like I do in a Silverlight app?

Re: setting the source of a bitmap image in C#

Eddy Vluggen1-Aug-12 22:10

Eddy Vluggen

1-Aug-12 22:10

Xarzu wrote:
How do I set the source in a WPF app like I do in a Silverlight app?

The Image class holds a FromStream[^]-method that you can use. The Bitmap class can be created and passed the Stream in it's constructor[^] as a parameter.

Bastard Programmer from Hell Suspicious | :suss:

if you can't read my code, try converting it here[^]

Re: setting the source of a bitmap image in C#

Xarzu6-Aug-12 6:40

Xarzu

6-Aug-12 6:40

This worked

System.IO.Stream stream = _scene.GetStream();
if (stream == null) return;
BitmapImage bitmap = new BitmapImage();
bitmap.BeginInit();
bitmap.StreamSource = stream;
bitmap.EndInit();

hi Chris Maunder

mohammad-mirshahi1-Aug-12 9:43

mohammad-mirshahi

1-Aug-12 9:43

hi Chris Maunder

please visit our site and send your poll my web !

WWW.ZUNKAN.IR

very tancks... Wink | ;)

hi!
i am mohammad mirshahi,i live in iran.please contact me....

Re: hi Chris Maunder

Pete O'Hanlon1-Aug-12 9:46

Pete O'Hanlon

1-Aug-12 9:46

Chris tends not to frequent this forum. If you need to get in touch with him, you need to post in the Site Bugs and Suggestions forum which is the best location to find him.

I seriously doubt you will get much joy though - I took a look at your site. Code Project is an English language site - why do you think part of it will sit well with your site?

*pre-emptive celebratory nipple tassle jiggle* - Sean Ewington

"Mind bleach! Send me mind bleach!" - Nagy Vilmos

CodeStash - Online Snippet Management | My blog | MoXAML PowerToys | Mole 2010 - debugging made easier

SetDate of system from inside of our program

Fred 341-Aug-12 4:15

Fred 34

1-Aug-12 4:15

[DllImport("kernel32.dll", EntryPoint = "SetSystemTime", SetLastError = true)]
public extern static bool Win32SetSystemTime(ref SystemTime sysTime);

By the above code I can change the system date of many version of MicroSoft Windows 7, but doesn't work on all of them. Do I miss something?

Re: SetDate of system from inside of our program

Pete O'Hanlon1-Aug-12 4:22

Pete O'Hanlon

1-Aug-12 4:22

As this call requires the SE_SYSTEMTIME_NAME privilege, I suspect you've hit a permissions issue.

*pre-emptive celebratory nipple tassle jiggle* - Sean Ewington

"Mind bleach! Send me mind bleach!" - Nagy Vilmos

CodeStash - Online Snippet Management | My blog | MoXAML PowerToys | Mole 2010 - debugging made easier

Re: SetDate of system from inside of our program

Dave Kreskowiak1-Aug-12 4:47

Dave Kreskowiak

1-Aug-12 4:47

Only an administrator account can change the system time.

If your code is launched by a normal user it's not going to work.

A guide to posting questions on CodeProject[^]

Dave Kreskowiak

How to refuse changes of controls in a form ?

taibc1-Aug-12 0:36

taibc

1-Aug-12 0:36

Hi friends,

Are there any methods to refuse changes of controls in a form ?

For example: I have a form that include one text box: txtNumber, and one Exit button.

At the first time, txtNumber.Text = "30" (When showing form)

Then, I changed the its value into "45". After that, I don't want to accept changes, I clicked the Exit button. Then txtNumber.Text is still "45". I want this value is "30".

Are there any method to refuse changes of TextBox in this case ?

Thanks and regards,

Re: How to refuse changes of controls in a form ?

Pete O'Hanlon1-Aug-12 0:39

Pete O'Hanlon

1-Aug-12 0:39

Simply set the ReadOnly property to true to prevent anybody from being able to change it via the UI.

*pre-emptive celebratory nipple tassle jiggle* - Sean Ewington

"Mind bleach! Send me mind bleach!" - Nagy Vilmos

CodeStash - Online Snippet Management | My blog | MoXAML PowerToys | Mole 2010 - debugging made easier

Re: How to refuse changes of controls in a form ?

taibc1-Aug-12 0:42

taibc

1-Aug-12 0:42

allow to change (not Readonly)

Re: How to refuse changes of controls in a form ?

Ed Hill _5_1-Aug-12 0:47

Ed Hill _5_

1-Aug-12 0:47

Are you meaning that you want to be able to either commit the changes if a "save/Commit" button is pressed, and undo changes if the exit button is pressed?

If that is the case, your exit button could simply trigger the method you used to set the values when showing the form.

Re: How to refuse changes of controls in a form ?

taibc1-Aug-12 0:50

taibc

1-Aug-12 0:50

Thanks Ed Hill_5_,

That is my mean, I will try it

Re: How to refuse changes of controls in a form ?

Pete O'Hanlon1-Aug-12 0:54

Pete O'Hanlon

1-Aug-12 0:54

Please, in future, try to be clearer with your questions. There is no way, from your original post, that I would have been able to guess what your question actually was.

*pre-emptive celebratory nipple tassle jiggle* - Sean Ewington

"Mind bleach! Send me mind bleach!" - Nagy Vilmos

CodeStash - Online Snippet Management | My blog | MoXAML PowerToys | Mole 2010 - debugging made easier

Re: How to refuse changes of controls in a form ?

Fred 341-Aug-12 4:28

Fred 34

1-Aug-12 4:28

simply save the pre value and return it in case of pressing exit buttom.

Use Ctrl+Left/Right to switch messages, Ctrl+Up/Down to switch threads, Ctrl+Shift+Left/Right to switch pages.