Am running asp.net application with access database using gridview application..while running i got the run time error as
Object reference not set to an instance of an object.
Line 41: RadioButtonList rblGender = (RadioButtonList)GridView1.Rows[e.RowIndex].FindControl("rbGenderEdit");
Line 42:DropDownList ddlStatus = (DropDownList)GridView1.Rows[e.RowIndex].FindControl("ddlStatusEdit");
Line 43:SqlDataSource1.UpdateParameters["Sex"].DefaultValue = rblGender.SelectedValue;
Line 44:SqlDataSource1.UpdateParameters["MaritalStauts"].DefaultValue = ddlStatus.SelectedValue;
Line 45: }
I got this error specially in line 43..
So rblGender.SelectedValue or rblGender is null...
Perhaps the problen is with rblGender
Make assignment as follows:
RadioButtonList rblGender = GridView1.Rows[e.RowIndex].FindControl("rbGenderEdit") as RadioButtonList;
And then check for nullability:
if (rblGender == null)
{
//show error
}
RadioButtonList rblGender = (RadioButtonList)GridView1.Rows[e.RowIndex].TemplateControl.FindControl("rbGenderEdit");
if it is in template field.
it can't find rbGenderEdit.
When you have a runtime error like this one, you should use your debugger to actually see what is going on behind the scene. Just put your breakpoint at the line 43 for instance, run your program in debug mode and start investigate to see what object has a null reference and try to fix it.
For instance take a look at the line 41, rblGender might be null...
EDIT
You must check if the objects that you are manipulating are null, this is part of the defensive programming techniques.
In your example, as others have said you can do it this way:
if(rblGender == null) {
// If you are running your program with a console
// Otherwise you should display this anywhere you can or in a log file.
Console.WriteLine("rblGender is null");
}
else if(rblGender.SelectedValue == null) {
Console.WriteLine("rblGender.SelectedValue is null");
}
Run your program and check what is being written! This is not going to solve your problem, but it is just going to tell you where your null reference is which will help you figure out what should be fixed!
But as I said earlier you can also debug your program properly by putting a breakpoint (you know the red ball when you click on the side of the window) at the line 43, and then run your program in debug mode! When the runtime error will fireup you will be able to check whether rblGender or rblGender.SelectedValue is null.
Also, from a more general point of view, checking your object against null references will prevent your application from crashing suddenly by managing the case where an objet might have a null reference at any given time. For instance you can say:
if(my_object is null)
{
myValue = "default";
}
else
{
myValue = my_objet.getValue();
}
This is just an example it could be done in a better way, using exceptions (try/catch/finally) for instance but the general idea is: check against null references!
Related
I have added System.Messaging to my assemblies.xml cause I need to use this in my Progress OpenEdge application. However I ran into a problem.
In C# when assigning:
m.Formatter = new XmlMessageFormatter(new[] { typeof(TrowConfiguration) });
TrowConfiguration myConfiguration = m.Body as TrowConfiguration;
However I now want to do this in ABL. I first used a method to read a string and just passed a CHARACTER EXTENT 1 INITIAL "System.String" to the XmlMessageFormatter object. However I tried changing this to the path of my object, TrowConfiguration, but this doesn't work and gives me an error.
If you're looking for the System.Type reference, use
Progress.Util.TypeHelper:GetType ("<your fully qualified type name>").
The code below is what I am using for my invoices to be Posted
ledgerJournalTable = header.ledgerJournalTable();
if (ledgerJournalTable.RecId > 0)
{
ledgerJournalCheckPost = ledgerJournalCheckPost::newLedgerJournalTable(ledgerJournalTable, NoYes::Yes, NoYes::Yes);
// Post only if there is succesful validation.
if (ledgerJournalCheckPost.validate())
{
ledgerJournalCheckPost.run();
}
else
{
info("Error.");
}
}
but there is always an error that says:
"Journal does not exist"
All the values that I've placed on the fields are correct because when I tried to use the same values manually, it was posted.
What could be wrong when that error pops up?
Edit1: As I've used breakpoint, I found out that in LedgerJournalCheckPost.validate() the ledgerJournalTable.JournalNum is empty "".
Found out that the ledgerJournalCheckPost.run() already has/calls the validate() method inside it, so there's no need to call the validate() method. However, I still don't know how to solve if you're going to use the validate() method through x++o code.
I am using ASP.Net 3.5 with C#,Development ID:Visual Studio 2008. When I am using
Session["FileName1"] = "text1.txt"
it is working fine, but then I am using
number1=17;
string FileName1="FileName1" + number1.toString();
then setting with
Session[FileName1]="text1.txt";
gives me runtime error
The session state information is invalid and might be corrupted
at System.Web.SessionState.SessionStateItemCollection.Deserializer(BinaryReader reader)
Can anybody solve my problem, when I am using string in the Session variable? Remember it works on my development machine (meaning local Visual Studio) but when deployed to the server it gives mentioned error.
Make sure the FileName1 variable is not null before trying to access it via the Session[FileName1] syntax...
Here's a link to someone else that was having the same problem:
http://forums.asp.net/t/1069600.aspx
Here's his answer:
In the code, I found the following line:
//some code
Session.Add(sessionVarName, sessionVarValue);
//some other code
Apparently, because of some dirty data, there is a time when
sessionVarName is null.
Session.Add will not throw any exception in this case, and if your
Session Mode is "InProc", there will be no problem. However, if your
Session Mode is "SQLServer", during deserialization of the session
store, you will got the exception that I got. So, to filter out dirty
data, I modified the code to become:
if (sessionVarName != null)
{
//somecode
Session.Add(sessionVarName, sessionVarValue);
//some other code
}
the reason of your error is
xyz = new Guid() is also xyz= Guid.Empty;
so when you try to convert to string it's throw error.
just modify you code something like that.
Guid guId = System.Guid.NewGuid();
string x = guId .ToString();
string FileName1="text1.txt" + x;
Session[FileName1]="text1.txt";
Check your values before storing them in session they may cause this exception during deserialization of the session store, Filter your data .
Check Here
if(!string.IsNullOrEmpty(FileName1))
{
Session.Add(FileName1, "text1.txt");
}
Or check for Invalid characters in your string .
You can add the Value into session Like this
string FileName1="FileName1" + number1.toString();
if(!string.IsNullOrEmpty(FileName1))
{
Session.Add(FileName1, "text1.txt");
}
I've written a simple code to keep a USerID with the help of session. However I can't get Session value although it's not null. I've done exactly the way microsoft official tutorial says. Here's the code:
The code on the Default.aspx
string regCode = loginBase.getRegCodePerUser(txtLogin.Text);
Session["regCode"] = regCode;
//lblInfo.text=(string)Session["regCode"];When I check it shows the right string.It's OK
Response.Redirect("Selection.aspx");
I do not directly go to that page.I first go to Selection.aspx, then UpdateStages.
And this is the code on the other page(UpdateStages.apsx):
if ((string)Session["connSTR"] == null && (string)Session["user"] == null)
{
Response.Redirect("Default.aspx");
}
else if ((string)Session["regCode"]!=null)
{
regCode=(string)Session["regCode"];
lblInfo.Text = regCode;//Show nothing. Empty.
}
It might very well be that when you set the session variable:
Session["regCode"] = loginBase.getRegCodePerUser(txtLogin.Text);
That the username is not available yet and that is why it's returning an empty string, and I would assume that you are executing this code: lblStatus.Text =loginBase.getRegCodePerUser(txtLogin.Text); on a different page/after the user has logged in and that is why you get the value in the label when you assign it directly.
Put a breakpoint on where you set the Session variable and see if the value is being set.
Otherwise your session settings could be incorrect in your web.config which causes the session values to be cleared before you get to your second page where you are accessing it.
I have a Rect object that I'd like to create and set its properties only once. After that, I want to just modify its properties since it already exists. This is my general idea
if(theRect == undefined){
Alert.show("creating");
var theRect:Rect = new Rect();
//then set properties
addElement(theRect); //then add it using addElement because addChild() does not work
} else {
Alert.show("updating");
//no need to create it since it's already been created
//just access and change the properties
}
I tried several ways and combinations for the if conditional check:
if(theRect == undefined){
if(theRect == null){
declaring and not declaring `var theRect:Rect;` before the if check
declaring and instantiating to null before the if check `var theRect:Rect = null;`
but can't get the desired effect. Everytime this code block runs, and depending on which version I've used, it either gives me a "can't access null object" error or the if statement always evaluates to true and creates a new Rect object and I get the "creating" Alert.
What's the right way of creating that Rect but only if doesn't exist?
You have some scoping issues in the code you presented.
What I think you want to do is:
var theRect:Rect;
...
if(theRect == null)
{
theRect = new Rect();
...
}
...
You need to first declare theRect, but you don't have to create it. You can instantiate it lazily later by checking if it is null.
The way you have it set up, you created a local version of theRect inside your if statement that would not be visible elsewhere. You will also get an error trying to access theRect if you did not declare it beforehand.