Can I use loops in repeater? Is it recommended?

My datasource has an Rating dataItem contains an integer from 0 to 5. I'd like to print stars accordignly.

I'm trying to do it within Repeater control:

<b>Rating:</b>

<% for (int j = 1; j <= DataBinder.Eval(Container.DataItem, "Rating"); j++)
{  %>
<img src="App_Pics/fullstar.png" />
<% }
for (int j = 1; j <= 5 - DataBinder.Eval(Container.DataItem, "Rating"); j++)
{ %>
<img src="App_Pics/emptystar.png" />
<%} %>

1. I get the error The name 'Container' does not exist in the current context. It is weird, because when I used <%# DataBinder.Eval(Container.DataItem, "Name")%> a line before, it worked great.
2. Is it clever to include loops in my aspx page? I think it's not very convenie开发者_开发知识库nt. What's my alternatives?
3. What's that # means?

Thank you very much.

The # indicates code to be executed when data-binding occurs (i.e. when DataBind() is called on the control or the page). The <%# %> syntax is the data-binding equivilent of <%= %> so unfortunately you can't just wrap your loop in <%# %> blocks and be done with it.

You can around this limitation by implementing a code-behind method and passing the rating to the method:

<%# GetStars(Convert.ToInt32(DataBinder.Eval(Container.DataItem, "Rating"))) %>

And then implement the method as:

protected string GetStars(int rating)
{
    string output = string.Empty;
    for (int j = 1; j <= rating; j++) output += "<img src=\"App_Pics/fullstar.png\" />";
    for (int j = 1; j <= 5 - rating; j++) output += "<img src=\"App_Pics/emptystar.png\" />";
    return output;
}

The # indicates a databound item, which is why you're seeing the error you've mentioned; you're using DataBinding outside of it's context.

The best solution would be to convert your star rater into an external control (an ascx control). You can add a property called "Rating", assign it from your databound context, and do the looping within the star rater control.

Point 2, you certainly can do it, and you'll find a few examples of it in tutorials and stuff. Personally I like to try and keep as much code as possible in the codebehind, but sometimes it's not worth it...

I would not recommend using a loop that way. There are, of course, ways to put 5 images together like you need them with stars on or off, but another idea is to simply create 6 static images, with 0 to 5 stars turned on. 0star.jpg, 1star.jpg, etc. Then your "rating" value can be used simply to generate the appropriate filename.

I'm not sure loops are such a great idea with a Repeater control. Better practise is to loop the DataSource itself (in the code-behind), so the Repeater only needs a single iteration to render the HTML.

If you need some composite HTML structure for display, I'd go with jvenema's solution and use another UserControl to render it.

The best would be for me to have something like :

codebehind :

protected List<int> Stars = new List<int> { 1, 2, 3, 4, 5 };
protected int RankingStars = 3;

aspx :

<asp:Repeater runat=server ID=C_Rep_StarsFull DataSource=Stars >
    <ItemTemplate>
          <img src="App_Pics/fullstar.png" runat=server 
                visible=<%# RankingStars >= (int)Container.DataItem %>/>
    </ItemTemplate>
</asp:Repeater>
<asp:Repeater runat=server ID=C_Rep_StarsEmpty DataSource=Stars >
    <ItemTemplate>
          <img  src="App_Pics/emptystar.png" runat=server 
                visible=<%# RankingStars < (int)Container.DataItem %>/>
    </ItemTemplate>
</asp:Repeater>