在ASP.NET中，如何在字典中存储控件

Question

I am storing ASP.NET Controls (Tables, Buttons, TextBoxes) in a Dictionary in a webform application, so that they can be accessed directly from user controls, instead of having to do a recursive search for them from other user controls. When they are added to the dictionary, I can verify that the visible control on the .ascx control is identical to the object in the Dictionary: X == Y returns true. But later on, when I want to do something like changing a background color, or disabling a button, X == Y returns false. A change that I make to the object in the Dictionary (which is declared as static) is not reflected in the visible GUI control.

How do I correct this?

Answer 1

(it's difficult to give you a helpful answer without seeing any code, and without understanding what you're trying to achieve, but ...)

Whenever a Postback is made, a new instance of the page and all its controls is created. Therefore the control instances stored in your dictionary no longer match with the control instances on the current page instance. They are still the instances created when the page was requested for the first time.

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But in any case, storing control instances in a static dictionary is a very bad idea (eg think about what happens when multiple users call your page in parallel).

Please explain what you want to achieve and why you think your dictionary is necessary. It will then probably be easier to help you.

Answer 2

The dictionary stores information about each control. However, the controls that the UI displays are separate. Every time you make a change to one element in the dictionary, you have to set the actual UI components to = their corresponding dictionary element. So

Dictionary["textBoxExampleKey"].Text = "blah";

won't change the actual textbox. To update the textbox to match the value in the dictionary, do`

textBoxExample.Text = Dictionary["textBoxExampleKey"].Text;

I recommend making a method that updates the entire UI to match the dictionary for the sake of simplicity. So this method would be something like

private void UpdateUI()
{
    textBoxExample.Text = Dictionary["textBoxExampleKey"].Text;
    labelExample.Text = Dictionary["labelExampleKey"].Text;
    listBoxExample.DataSource = Dictionary["listBoxExampleKey"].DataSource;
    Refresh();
}

The "Refresh()" method reloads your UI so that all changes are made visible, which could also be part of your problem.

TL;DR: Update your actual controls, refresh your UI.