When and Why to Use Page.ResolveUrl in ASP.NET

asp.nethtmlwebforms

So, i had a discussion with a colleague on why and where should we use Page.ResolveUrl("~/PageUrl.aspx") instead of ./PageUrl.aspx.

For example, are there any differences between:

<a href='<%= Page.ResolveUrl("~/Home.aspx")%>' runat="server"> Home </a>

and

<a href="./Home.aspx" runat="server"> Home </a> ?

Here is what i found on msdn but the only benefit i see from there is that Page.ResolveUrl is good at resolving urls for content ( images & stuff like that)

Here you can find a good example on why to use Page.ResolveUrl but Babu Naresh Narra does not say anything about the ./ usage.

Are there any other benefits that Page.ResolveUrl gives over the basic ./ approach?

Best Answer

Suppose you had made a User Control that you were going to use on many different pages. Part of the User Control is a link to the Home page.

If you use the User Control on a page that is more than one level deep: i.e http://website/folder1/APageWithUserControlOn.aspx

then this :

<a href="./Home.aspx" runat="server"> Home </a>

will resolve to http://website/folder1/Home.aspx

Where as this:

 <a href="<%= Page.ResolveUrl("~/Home.aspx")%>" runat="server">

Will resolve to http://website/home.aspx which is much more likely to be what you wanted as the link will be correct on any page. The server side Page.Resolve resolved the url from the root when using '~'. You might thing you could use '/Home.aspx' in the first example, but this doesn't work as expected when using Virtual Directories.

Related Solutions

Should I strictly follow every single HTML and CSS Standard

Product first, then polish.

Get your site/application/game doing what it's supposed to do. Get it up and running, and get people interested.

Then, when you have the time, go back and polish it up. But only because you care, not because anybody else does.

Of course, if the non-compliance issues mean people can't view it, or it's unreadably ugly, or it takes a month to load, or it's hard to maintain, or it crashes the browser, this is a major problem. But it would still be a major problem even if you were standards-compliant.

Ordinary users do not look at the source for a website that isn't loading and go, "Well, it's not displaying the pictures, but it's completely W3C-compliant". They simply browse to another website and never return.

Bottom line, standards are there to make writing browsers easier, and to close up potential security holes. Amazon, Penny-Arcade and Stack Overflow do not make their money from running a standard-compliant website. And unless you're in a website-writing competition, neither will you.

ASP.NET – How to Structure an XML-Based Order Form

I think that part of the issue you may be facing is that ASP.Net tries to manage the naming of the items for your when it's rendered to the client, so in your ASP page you may name your control "txtFirstName" but inside a nested reapeater it will look like "Repeater1$ctl00$Repeater2$ctl00$txtFirstName." You probably already know that, but the issue is when you make the objects dynamic, as loaded from the XmlDataSource, it doesn't do the mapping for you back to the name. You can still use the Request object to pull the values.

So, for example, I pulled the XmlDataSource example off of MSDN (http://msdn.microsoft.com/en-us/library/system.web.ui.webcontrols.xmldatasource.aspx) and added some checkboxes to the nested repeater that contains the orders. When I click submit, just as a test, I view the Params collection from the Request object and if they contain the ID of the checkboxes I'm searching for I output their value.

Let me know if this helps, or you need more.

Below is the code

order.xml:

    <?xml version="1.0" encoding="iso-8859-1"?>
    <orders>
        <order>
        <customer id="12345" />
            <customername>
                <firstn>John</firstn>
                <lastn>Smith</lastn>
            </customername>
        <transaction id="12345" />
        <shipaddress>
            <address1>1234 Tenth Avenue</address1>
            <city>Bellevue</city>
            <state>Washington</state>
            <zip>98001</zip>
        </shipaddress>
        <summary>
           <item dept="tools">screwdriver</item>
           <item dept="tools">hammer</item>
           <item dept="plumbing">fixture</item>
        </summary>
      </order>
    </orders>

And the webpage:

<%@ Page Language="C#" %>
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN""http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">

<html xmlns="http://www.w3.org/1999/xhtml" >
  <head id="Head1" runat="server">
    <title>Order</title>
    <script runat="server">
        void btnGetSubmit_Click(Object sender, EventArgs e)
        {
            foreach (string c in this.Request.Params)
            {
                if (c.IndexOf("chkIncludeItem", StringComparison.InvariantCultureIgnoreCase) > -1)
                {
                    Response.Write(string.Format("{0} - {1}<br />", c, this.Request.Params[c]));
                }
            }
        }
    </script>
</head>
<body>
    <form id="form1" runat="server">
      <asp:XmlDataSource
        runat="server"
        id="XmlDataSource1"
        XPath="orders/order"
        DataFile="order.xml" />

      <asp:Repeater ID="Repeater1"
        runat="server"
        DataSourceID="XmlDataSource1">
        <ItemTemplate>
            <h2>Order</h2>
            <table>
              <tr>
                <td>Customer</td>
                <td><%#XPath("customer/@id")%></td>
                <td id="tdFirstName"><%#XPath("customername/firstn")%></td>
                <td id="tdLastName"><%#XPath("customername/lastn")%></td>
              </tr>
              <tr>
                <td>Ship To</td>
                <td><%#XPath("shipaddress/address1")%></font></td>
                <td><%#XPath("shipaddress/city")%></td>
                <td><%#XPath("shipaddress/state")%>,
                    <%#XPath("shipaddress/zip")%></td>
              </tr>
            </table>
            <h3>Order Summary</h3>
            <asp:Repeater ID="Repeater2"
                 DataSource='<%#XPathSelect("summary/item")%>'
                 runat="server">
                <ItemTemplate>
                    <div>

                     <b><%#XPath("@dept")%></b> -
                         <%#XPath(".")%><asp:CheckBox ID="chkIncludeItem" runat="server" /><br />
                    </div>
                </ItemTemplate>
            </asp:Repeater>
            <hr />
        </ItemTemplate>
    </asp:Repeater>

    <asp:Button ID="btnGetSubmit" runat="server" OnClick="btnGetSubmit_Click" Text="Submit" />
  </form>
  </body>
</html>

Best Answer

Related Solutions

Should I strictly follow every single HTML and CSS Standard

ASP.NET – How to Structure an XML-Based Order Form

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