public static Object reference not set error

Question

Issue: I have a gridview that i to reference. However when i try to reference it i get an error.

Error:

System.NullReferenceException: 'Object reference not set to an instance of an object.'

gridname was null.

main.aspx.cs

namespace WebApplication1
{
    public partial class About : Page
    {


    protected void Page_Load(object sender, EventArgs e)
    {
        DataTable dt = datagridpopulate.Main("supplier", 0, null);
        GridView1.DataSource = dt;
        GridView1.DataBind();
    }

Weird point: This was working yesterday and i made some changes to clean my code and now i cant figure out what ive changed thats made it stop working

Additional notes: Ive tried to just print the control as a string to a popup window function i have. (pop_up.main(GridView1.ToString());) however it still states its null.

I would really appreciate your assistance :)

---- Error narrowed down to: Okay so this is causing the error: public static global::System.Web.UI.WebControls.GridView GridView1; it worked when it was: protected global::System.Web.UI.WebControls.GridView GridView1;

The issue is i need to access the control from other class files. So it needs to be public static. How do get to keep it public static and also use object reference without the error?

Have you tried debugging your code to check if all the parameters are being properly passed to your `datagridpopulate.Main` function? From the looks of it, your function is not giving any data to your DataTable. — Rahul Sharma, Nov 25 '19 at 09:17
Hey, Yes. I have tried to just print the control in a popup window. pop_up.main(GridView1.ToString()); However it still says its not set/ is null. So its unrelated to the dt — Random Stuff, Nov 25 '19 at 09:24
Try this: `pop_up.main(Convert.ToString(GridView1));` and see what value do you get there — Rahul Sharma, Nov 25 '19 at 09:27
Hmm, there is no error. The popup comes up however it is blank. Im not sure what that indicates. — Random Stuff, Nov 25 '19 at 09:30
Well it indicates that your `GridView1` is empty and hence it returns nothing. Try seeing what values you get when your `GridView1` is populated with some data. — Rahul Sharma, Nov 25 '19 at 09:32
Thats interesting though. Shouldn't the gridview be empty until its bound to? which is what im trying to do? — Random Stuff, Nov 25 '19 at 09:35
Maybe this will help: https://stackoverflow.com/questions/354369/gridview-show-headers-on-empty-data-source — Rahul Sharma, Nov 25 '19 at 09:37
I cant bind data to it. thats the issue. i had a look at the link and it does not help — Random Stuff, Nov 25 '19 at 09:50
A similar problem to yours, hope this helps: https://stackoverflow.com/questions/20825164/i-can-not-see-my-gridview-in-page-load — Rahul Sharma, Nov 25 '19 at 09:55
Okay, please show what you have got till now on this problem? — Rahul Sharma, Nov 25 '19 at 10:50
Okay so this is causing the error: public static global::System.Web.UI.WebControls.GridView GridView1; it worked when it was: protected global::System.Web.UI.WebControls.GridView GridView1; — Random Stuff, Nov 25 '19 at 10:54
`> System.NullReferenceException: 'Object reference not set to an > instance of an object.' > > gridname was null.` — Random Stuff, Nov 25 '19 at 10:57
Okay, take a look at this question. It may help you achieve what you want: https://stackoverflow.com/questions/1165321/change-the-access-modifiers-of-asp-net-controls — Rahul Sharma, Nov 25 '19 at 11:05
@devio , If i dont have it as static i get this error in other code. Error` CS0120 An object reference is required for the non-static field, method, or property 'About.suppliers_GridView1' ` — Random Stuff, Nov 25 '19 at 13:45
Yes thank you. I ended up removing the static from my control. This created an access error which i fixed via creating instances and passing the control directly from the main form. — Random Stuff, Nov 27 '19 at 07:33

score 0 · Answer 1 · answered Nov 25 '19 at 09:08

0

try to remove About.

Create_P_O_functions.populatedatagrid(About.GridView1, "supplier", 0, null);

to

Create_P_O_functions.populatedatagrid(GridView1, "supplier", 0, null);

Your GridView is create two link above. I think as you, GridView is not on About page yet.

answered Nov 25 '19 at 09:08

Guillaume Durupt

44
6

I removed it. However it did not fix it – Random Stuff Nov 25 '19 at 09:14
I put the function within the page_load to help find where the issue is. I get the same error though. I've updated my question to reflect this. – Random Stuff Nov 25 '19 at 09:16
try to remove static of your function – Guillaume Durupt Nov 25 '19 at 09:17
I updated to not actually use that static function and im still getting the error – Random Stuff Nov 25 '19 at 09:21
lol, with the code you have edit, the error is throw where ? on GridView1.DataBind(); ? Your dt is fill ? – Guillaume Durupt Nov 25 '19 at 09:27
Its getting the error here: GridView1.DataSource = dt; – Random Stuff Nov 25 '19 at 09:31
the dt is full though. It has 7 rows that ive just confirmed – Random Stuff Nov 25 '19 at 09:31
Ive just dragged it out from the toolbox into the designer. It has autogenerate columns true – Random Stuff Nov 25 '19 at 09:34
Sorry I don't understand and haven't idea. Try to create another simple page and do the same thing, just add your gridview and call your method. I know you can access to the About.designer.vb in solution explorer and look if gridview is declare in public ? Sorry I can't help you more :( – Guillaume Durupt Nov 25 '19 at 09:52
I narrowed it down. If you wanted to have a look at it? – Random Stuff Nov 25 '19 at 10:49
I don't think you can pass a control in a static method. Remove the static no ? Why would you like the methds to be static ? – Guillaume Durupt Nov 25 '19 at 11:01
If i dont have it as static i get this error in other code. Error` CS0120 An object reference is required for the non-static field, method, or property 'About.suppliers_GridView1' ` – Random Stuff Nov 25 '19 at 13:46
i think, you must correct this error and remove the static on the method. you can copy the line where the error cs0120 throw? – Guillaume Durupt Nov 25 '19 at 13:51
Okay, Should i then create a new question on this site with the new error and related info? – Random Stuff Nov 25 '19 at 13:57
I ended up removing the static from my control. This created an access error which i fixed via creating instances and passing the control directly from the main form. Thank you – Random Stuff Nov 27 '19 at 07:33

public static Object reference not set error

1 Answers1