C# Discussion Boards - CodeProject

Re: Fill Combobox with Large amount of Data

OriginalGriff29-Dec-12 4:08

29-Dec-12 4:08

To add to what Eddy said - it's a very silly idea to put that many items into a control of any sort if you expect the user to have to pick one of them himself.
Think about it as a user: how are you going to find the one item you want out of 55,000? How much time are you going to waste looking?

Find a better solution! Search, filter, whatever - but not "here's a big list - you sort it out".

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Re: Fill Combobox with Large amount of Data

Nabawoka29-Dec-12 23:56

Nabawoka

29-Dec-12 23:56

thank OriginalGriff

Re: Fill Combobox with Large amount of Data

SledgeHammer0129-Dec-12 8:02

SledgeHammer01

29-Dec-12 8:02

As others have said 55,000 items in a combobox is a HORRIBLE idea. How is anybody going to find an item in there? Find a better design.

Re: Fill Combobox with Large amount of Data

Nabawoka29-Dec-12 23:56

Nabawoka

29-Dec-12 23:56

HORRIBLE idea Cry | :((

thanks SledgeHammer01

Authentication using HTTPWebRequest

logicon29-Dec-12 1:14

logicon

29-Dec-12 1:14

Hello Everyone,

I am trying to access a page which is secure behind a login system. I do have credentials, but I am trying to automate this as I have to download this page every month.

When I try to use HTTPWebRequest, it doesn't works. I tried to investigate this using Fiddler as well, and here is the log:

Protocol  Host                                   URL
HTTP     TUNNEL to                    subdomain-x.site.com/needed-page.html  <- My request
HTTP     TUNNEL to                    subdomain-y.site.com
:
.
HTTPS    subdomain-y.site.com some-url

What I am trying is:

1. Create Web Request
2. Create Cookie Container
3. Create Network Credentials
4. Create Headers
5. Get Response

However, this returns the Login Page itself. Any help will be highly appreciable.

Re: Authentication using HTTPWebRequest

SledgeHammer0129-Dec-12 9:31

SledgeHammer01

29-Dec-12 9:31

Impossible to say with the info you've given. You need to analyze the login page source code to see how the credentials are sent back to the server and how the actual page you want to access is authenticated. If its just a random SSL page, you just need to fill in the HTTPWebRequest.Credentials object.

Save and Retrieve Image

nirmalgopalakrishnan28-Dec-12 22:02

nirmalgopalakrishnan

28-Dec-12 22:02

Hi All,

Could you please assist me in saving and retrieve images to MySQL database using an Image Path.

Let me know, if you require any additional information to assist me.

Thank you,
Nirmal

Re: Save and Retrieve Image

Richard MacCutchan28-Dec-12 23:18

Richard MacCutchan

28-Dec-12 23:18

You need to explain what assistance you need. If you want to save the actual image, then save it as a byte stream or blob (whatever is the MySQL equivalent). If you want to save the file's location then it is just a character string.

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Re: Save and Retrieve Image

nirmalgopalakrishnan29-Dec-12 5:15

nirmalgopalakrishnan

29-Dec-12 5:15

Thank you for your response.

I am saving the image as LongBlob. But retrieving an image through search function, i get parameter not valid error.

byte[] bytesofphotosretrive;
bytesofphotosretrive = (byte[])r["photo"];
MemoryStream mst = new MemoryStream(bytesofphotosretrive);
{
frm1.pictureBox5.Image = Image.FromStream(mst);
}

Please assist.

Regards,
Nirmal

Re: Save and Retrieve Image

Richard MacCutchan29-Dec-12 5:57

Richard MacCutchan

29-Dec-12 5:57

nirmalgopalakrishnan wrote:
i get parameter not valid error.

Where?

One of these days I'm going to think of a really clever signature.

Re: Save and Retrieve Image

nirmalgopalakrishnan29-Dec-12 6:07

nirmalgopalakrishnan

29-Dec-12 6:07

byte[] bytesofphotosretrive;
bytesofphotosretrive = (byte[])r["photo"];
MemoryStream mst = new MemoryStream(bytesofphotosretrive);
{
frm1.pictureBox5.Image = Image.FromStream(mst);
}

the error points to this parameter : frm1.pictureBox5.Image = Image.FromStream(mst);

Re: Save and Retrieve Image

Richard MacCutchan29-Dec-12 6:17

Richard MacCutchan

29-Dec-12 6:17

Well it should not be too difficult to guess which parameter is in error. Use your debugger to step through the code and see exactly what is happening.

One of these days I'm going to think of a really clever signature.

Re: Save and Retrieve Image

nirmalgopalakrishnan29-Dec-12 19:14

nirmalgopalakrishnan

29-Dec-12 19:14

It's pointing to the error in line 164, which is as below:

frm1.pictureBox5.Image = Image.FromStream(mst);

The exception message is: "System.Argument.Exception: Parameter is not valid. at System.Drawing.Image.FromStream(Stream stream, Boolean useEmbeddedColorManagement, Boolean validateImageData) at System.Drawing.Image.FromStream(Stream stream)at btnResearch_Click(Object sender, EventArgs e) in D:\Mat\frmRecSearch.cs: line 164.

Re: Save and Retrieve Image

Richard MacCutchan29-Dec-12 21:22

Richard MacCutchan

29-Dec-12 21:22

Well we already know that. Have you used the debugger to try and determine why the parameter is invalid?

One of these days I'm going to think of a really clever signature.

Re: Save and Retrieve Image

nirmalgopalakrishnan30-Dec-12 19:57

nirmalgopalakrishnan

30-Dec-12 19:57

Could you please email me. nirmalkumarg3@gmail.com

Re: Save and Retrieve Image

Richard MacCutchan30-Dec-12 22:19

Richard MacCutchan

30-Dec-12 22:19

Sorry no, if you have issues to discuss around this problem then post them in this forum; that is why we use it.

One of these days I'm going to think of a really clever signature.

Re: Save and Retrieve Image

nirmalgopalakrishnan31-Dec-12 17:28

nirmalgopalakrishnan

31-Dec-12 17:28

Cool, no issues. It points to a null parameter in the debugger. But the same code, when executed with just an image add and retrieve (a new c# project), the application works really well. I am unable to determine what is the problem here Frown | :(

Re: Save and Retrieve Image

Richard MacCutchan31-Dec-12 22:50

Richard MacCutchan

31-Dec-12 22:50

nirmalgopalakrishnan wrote:
I am unable to determine what is the problem here

From a previous post you have the following code:

byte[] bytesofphotosretrive;
bytesofphotosretrive = (byte[])r["photo"];
MemoryStream mst = new MemoryStream(bytesofphotosretrive);
{
    frm1.pictureBox5.Image = Image.FromStream(mst);
}

So you need to find out why mst is null at this point. Your code is assuming that you always get a valid byte array from r (whatever that is), and hence a valid stream. However, if either of these commands do not return the expected result you are going to have a problem which you are not catering for. You should never assume that method calls like this will always succeed; add some error checks so you can diagnose it properly when it fails.

One of these days I'm going to think of a really clever signature.

Re: Save and Retrieve Image

Abhinav S28-Dec-12 23:38

Abhinav S

28-Dec-12 23:38

Try this link out -http://guruparan.blog.com/2011/06/15/saving-and-retriving-images-from-mysql-databases-using-c-part2/[^].
An image is opened and then saved to the database.

In particular, note how longblob has been used to save the image in the database.

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Re: Save and Retrieve Image

nirmalgopalakrishnan29-Dec-12 5:16

nirmalgopalakrishnan

29-Dec-12 5:16

Thank you for your response. The link which you provided was really helpful. But i am not sure how to include the same in my application, since i am saving data from 15 text boxes.

I am confused as to where to include the image details.

Regards,
Nirmal

Dynamic text box array and focus event

Everetts28-Dec-12 8:41

Everetts

28-Dec-12 8:41

I have a form that has an array of text boxes dynamically added to a splitcontainer on a form. I use the same array to add text boxes to the form twice (different data for different table). I would like to use an event handler, preferably once, to change background color to yellow when textbox[i] receives focus, and back to white when it loses focus. I am currently going around in circles. Can anyone help me? Thanks for your input
Everett

Re: Dynamic text box array and focus event

Eddy Vluggen28-Dec-12 10:25

Eddy Vluggen

28-Dec-12 10:25

Add in a lambda, at the point where you create the textboxes. Like the example below;

public Form1()
{
    InitializeComponent();

    var tb = new TextBox();
    tb.GotFocus += delegate (object s, EventArgs a)
    {
        (s as TextBox).BackColor = Color.Red;
    };
    tb.LostFocus += delegate(object s, EventArgs a)
    {
        (s as TextBox).BackColor = Color.Green;
    };
    Controls.Add(tb);
}

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Re: Dynamic text box array and focus event

bambuz28-Dec-12 14:33

bambuz

28-Dec-12 14:33

hi, your idea is right, but the textbox has't the event GotFocus & LostFocus, instead of, has the event Enter & Leave.
Wink | ;)

Re: Dynamic text box array and focus event

Everetts28-Dec-12 16:41

Everetts

28-Dec-12 16:41

Works beeeautiful. Thank you so much Eddy
Everett

Connection String in Properties.Settings

TheJudeDude28-Dec-12 7:47

TheJudeDude

28-Dec-12 7:47

I am rewriting a desktop application in VS2010 that was written in .Net 1.1. While doing so, I decided to add a couple of features to the app. One is a data source for a drop down list. I am using a local database file (.sdf) for the data.
I noticed in the <namespace>.Properties.Settings file that the connection string is a hard link to where I entered the file location (which is C:\Users\<username>\Documents\db\<filename>). I need this to be more dynamic, due to the fact this app will be on many different computers.
I tried editing to :

"Data Source = " + System.Environment.GetFolderPath(System.Environment.SpecialFolder.MyDocuments) + @"\dbs\latefee.sdf")]

But I receive the following error at compile time:

Error	1	An attribute argument must be a constant expression, typeof expression or array creation expression of an attribute parameter type	C:\Users\brian\AppData\Local\Temporary Projects\latefeedisc\Properties\Settings.Designer.cs	29	68	latefeedisc

How do I correct this?

Thank you in advance.

Jude

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