How exactly would you like me to "Quote values differently inside a '<% ... "value" ... %>' block"?

Visual Studio freaks out when your HTML contains nested quotes. Roy's solution (using single quotes for the attribute and double quotes for the databinder or function arguments) works unless you need to nest quotes, which occurs if you're including a Javascript call in a databinding statement:

<asp:TemplateColumn>
    <ItemTemplate>
        <a href="javascript:showPopup('\Popups\Edit.aspx?ID=<%# DataBinder.Eval(Container.DataItem,"itemID")%>')">edit</a>
    </ItemTemplate>
</asp:TemplateColumn> 

The problem here is that you need quotes around your href attribute, quotes around your javascript function argument, and quotes around your DataBinder.Eval string parameter. Tim sums it up pretty will here, but you're pretty much stuck with either  "Quote values differently inside a '<% ..."value"... %>' block." or "Place quotes around a '<% %>' block used as an atribute value or within a SELECT element." I haven't seen a good discussion on how to handle this well, so here's what I've come up with - please recommend something else if you've got a better solution.

We need a third quote, right? Well, one common solution is to use \u0022 - the VS UI doesn't see it as a quote and doesn't get confused, but the ASP.NET rendering engine writes it out as a quote:

<asp:TemplateColumn>
    <ItemTemplate>
        <a href ="javascript:showPopup(\u0022\Popups\Edit.aspx?ID=<%# DataBinder.Eval(Container.DataItem,"itemID")%>\u0022)">
        edit< /a>
    </ItemTemplate>
</asp:TemplateColumn> 

A better solution is to just escape the quote with a backslash (\"). The VS IDE handles that just fine:

<asp:TemplateColumn>
    <ItemTemplate>
        <a href ="javascript:showPopup(\"\Popups\Edit.aspx?ID=<%# DataBinder.Eval(Container.DataItem,"itemID")%>\")">
        edit< /a>
    </ItemTemplate>
</asp:TemplateColumn> 

Another solution is to use code behind to actually construct the links. I normally wouldn't use that unless there was a good amount of formatting, and even then you can get away from that with a format string in the DataBinder.Eval call. I usually see people recommend one-off functions for that kind of thing, but I prefer using something more generic. The following function will work in a page code behind, but could be made a static function and placed in a code library class: 

protected string BuildJavascriptLink(string format, params string[] input)
{
    format = format.Replace("{quote}","\"");
    string retval = string.Format(format,input);
    retval = retval.Replace("'","\"");
    return retval;
}

Now we could reference it in the code front with something like this:

<a href='<%# BuildJavascriptLink("javascript:showPopUp({quote}/PopUps/{0}{1}{quote},{2},{3})","StreetLevelMap.aspx?ID=",Convert.ToString(DataBinder.Eval(Container.DataItem,"Entity_ID")),"600","450") %>'>Street Map</a>

6 Comments

  • My solution is to ignore VS.Net.

  • I just recently made a simple popupHyperlink that inherits from Hyperlink.

    When rendering, it renders javascript statement in code;



    I usual use single double and escaped single quotes.

  • Second attempt (sorry Jon).



    The &lt;%#...%&gt; functionality is similar to &lt;%=...%&gt;.



    So the above could also be written as

    &lt;a href='&lt;%# &quot;javascript:showPopup('\popups\edit.aspx?id=&quot; + DataBinder.Eval(Container.DataItem,&quot;itemID&quot;) %&gt;'&gt;edit&lt;/a&gt;

  • Hi, Don!



    That's true, but sometimes you still run into problems quoting the parameters. The code you provided won't show in design view due to nested quotes - single quotes around the href attribute, double quotes around the string variable, and a single quote inside the javascript parameter.



    &lt;%# is not exactly functionally equivalent to &lt;%. The &lt;%# is executed within the databinding loop, whereas the &lt;% is executed once for the entire page. I know what you mean, though - they both work the same when they're rendering content.

  • True, Michael [MSFT], but that's only in ASP.NET 2.0.

  • hi,

    how to render if

    &quot;DataBinder.Eval(Container.DataItem,&quot;itemID&quot;)&quot; itself returns quote, for example itemid can be item'001

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