the code searches for a Textbox of name "TextBoxName" and retrieves the text value contained in it

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this.GetType().GetField("TextBoxName").GetValue(this).ToString();

Using this code i try to Retrieve TextBoxName.Text when user supplies the string "TextBoxName" but i get a nullreferencexception.

Posted 14-Feb-15 4:45am

Rahul Anand Jha

Updated 14-Feb-15 5:09am

v5

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OriginalGriff 14-Feb-15 11:01am

"Didnt Work!" is not a good error report - we have no idea what problem you are having, or what kind of help you are seeking.

Please, try to think about how you present the problem from the POV of the reader: Remember that we can't see your screen, access your HDD, or read your mind.

So try explaining this as if to someone on the other end of a phone, and perhaps that would help...

Use the "Improve question" widget to edit your question and provide better information.

BillWoodruff 14-Feb-15 18:32pm

Without knowing the context of this cryptic line of code, and what the two uses of 'this refer to ... there's no point in making a guess.

Sinisa Hajnal 16-Feb-15 2:35am

Why not use TextBoxName.Text? Try to improve question so that we know what you're trying to do, is this winforms, web, wcf...what is "this" in your code (you gave us no context).

gggustafson 16-Feb-15 10:57am

I believe that the Null Reference Exception is caused when this.GetType().GetField("TextBoxName").GetValue(this).ToString(); returns null. Are you testing for null? If not do so. Remember that anything that a user supplies should be considered as suspect. So if the user enters "foofoo" as the text box name, you will probably fail at GetField("foofoo").

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Ramza360 · Answer 1 · 2015-02-16T05:20:00

Your issue is that most likely the control being searched for is private or simply non-public. In the GetField call you should add Binding Flags to allow searching for the private / protected fields, if that's what you really want to do.

C#

// replace "txtBoxName" with the actual text form the text box.
FieldInfo info = this.GetType().GetField("txtBoxName", BindingFlags.Public | BindingFlags.NonPublic | BindingFlags.Instance);

if (null != info) {
    // Here get the value as an object or string if you 'know' it will always be a string
    object val = info.GetValue(this);
}

Mangal Deep Gupta · Answer 2 · 2015-02-16T22:31:00

Solution 2

Try it...

C#

<pre lang="c#">

(this.FindControl("textboxname") as TextBox ).Text

Posted 16-Feb-15 22:31pm

Mangal Deep Gupta