Postback does not reload all controls in the NameValueCollection

Question

Postback does not reload all controls in the NameValueCollection

Recently, I designed a custom User Control in asp.net.

public class InputMask : CompositeControl, IPostBackDataHandler, IPostBackEventHandler

Imagine the custom control is enclosed within a div element:

<div runat="server" id="inputArea">
    <asp:MaskInput runat="server" ID="ssn" ToolTip="SSN" Format="SSN" PartialMask="true" />
</div>

In the code behind, there is the following snippet:

 inputArea.Visible = False

During postback,

LoadPostData(string postDataKey, NameValueCollection postCollection)

does not contain the MaskInput key.

However, if you try this approach:

inputArea.Attributes.Add("style", "display:none")

The postCollection will have the MaskInput key present.

It seems that when using CSS to hide the div, the control is still rendered but invisible. On the other hand, with visible=false, the control is not even rendered at all.

Is there any workaround to retrieve the key in LoadPostData while using visible=false?

c#css asp.net custom-controls

Answer 1

Answer №1

To address and fix the issue at hand:

I made adjustments to the LoadPostData method as follows:

public override bool LoadPostData(string postDataKey, NameValueCollection postCollection) {
        this.Text = postCollection[ClientID + InputHiddenPostfix];
        return false;
    }

and updated it to:

public override bool LoadPostData(string postDataKey, NameValueCollection postCollection) {
        var key = ClientID + InputHiddenPostfix;
        string text = this.Text;
        if (postCollection.AllKeys.Any(k => k.Equals(key))) {
            string item = postCollection[key];
            if (this.ReadOnly || text.Equals(item, StringComparison.Ordinal)) {
                return false;
            }
            this.Text = item;
        } else {
            return false;
        }           
        return true;
    }

In addition, I modified the Text property to utilize ViewState

From:

    [Bindable(true)]
    [Category("Appearance")]
    [DefaultValue("")]
    public string Text { get; set; }

to

    [Localizable(true)]
    [PersistenceMode(PersistenceMode.EncodedInnerDefaultProperty)]
    [WebCategory("Appearance")]
    [WebSysDescription("MaskBase_Text")]
    [Bindable(true, BindingDirection.TwoWay)]
    [DefaultValue("")]
        public string Text {
        get {
            string item = (string)this.ViewState["Text"];
            if (item != null) {
                return item;
            }
            return string.Empty;
        }
        set {
            this.ViewState["Text"] = value;
        }
    }

Answer 2

To address and fix the issue at hand:

I made adjustments to the LoadPostData method as follows:

public override bool LoadPostData(string postDataKey, NameValueCollection postCollection) {
        this.Text = postCollection[ClientID + InputHiddenPostfix];
        return false;
    }

and updated it to:

public override bool LoadPostData(string postDataKey, NameValueCollection postCollection) {
        var key = ClientID + InputHiddenPostfix;
        string text = this.Text;
        if (postCollection.AllKeys.Any(k => k.Equals(key))) {
            string item = postCollection[key];
            if (this.ReadOnly || text.Equals(item, StringComparison.Ordinal)) {
                return false;
            }
            this.Text = item;
        } else {
            return false;
        }           
        return true;
    }

In addition, I modified the Text property to utilize ViewState

From:

    [Bindable(true)]
    [Category("Appearance")]
    [DefaultValue("")]
    public string Text { get; set; }

to

    [Localizable(true)]
    [PersistenceMode(PersistenceMode.EncodedInnerDefaultProperty)]
    [WebCategory("Appearance")]
    [WebSysDescription("MaskBase_Text")]
    [Bindable(true, BindingDirection.TwoWay)]
    [DefaultValue("")]
        public string Text {
        get {
            string item = (string)this.ViewState["Text"];
            if (item != null) {
                return item;
            }
            return string.Empty;
        }
        set {
            this.ViewState["Text"] = value;
        }
    }

Postback does not reload all controls in the NameValueCollection

Answer №1

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