Nested Repeaters in ASP.NET

I have a class that contains hierarchical data. I want to present this data in my webapp using nested repeaters. How do I do this? I’ve only ever done one level of nesting, how do I do say five levels?

Each item can have zero or many sub items. I’m basically just indenting at each subleveling using some css stuff. I do not want to use the treeview control, I want to strictly stick with a repeater.

My data comes from a database. I have an item datatable with some basic properties.


Then I have a many to many table with:

I’m iterating through each item and displaying its children; and its children’s children. I assume this would best be accomplished with nested repeaters, but I could be wrong.


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Method 1

I’ve found that the simplest way to do nested repeaters without worrying about databinding events is to just set the DataSource using <%# %> syntax.

For example:

<asp:Repeater runat="server" id="Departments">
    Name: <%# Eval("DeptName") %>
    <asp:Repeater runat="server" DataSource='<%# Eval("Employees") %>'>
      <ItemTemplate><%# Eval("Name") %></ItemTemplate>

This is presuming that your Departments class has an Employees property – eg:
public class Department {
  public string DeptName {get; set;}
  public IEnumerable<Employee> Employees {get; set;}
public class Employee {
  public string Name {get; set;}

If your outer-repeater object doesn’t have a property corresponding to the inner-repeater object you can still use this trick, by adding a method in your code-behind that does the calculation. So your inner repeater might become:
<asp:Repeater runat="server" DataSource='<%# GetEmployees(Container.DataItem) %>'>

and then GetEmployees might look something like:
protected IEnumerable<Employee> GetEmployees(object item) {
  var dept = (Department) item;
  // then do whatever is necessary to get the employees from dept
  return employees;

Method 2

It’s always cleaner to deal with the datasource than messing about with ItemDataBound, but this is even more the case when nesting Repeaters:

<asp:Repeater DataSource="<%#ColOfCol%>" runat="server">
      <asp:Repeater DataSource="<%#Container.DataItem%>" runat="server">

The inner datasource could also be an evaluated property, or a call to a method that returns the enumeration wanted. Just be aware that it will be called with an object. I prefer to write the specific version, and then overload:
protected IEnumerable<string> GetNames(Family fam)
  foreach(Person p in fam.Members)
    yield return p.FirstName + " " + p.Surname;
protected IEnumerable<string> GetNames(object famObj)
    return GetNames((Family)famObj);

One thing to be aware of is that if you want to get the current object in the parent repeater than you have to obtain it with:

Method 3

You can nest repeaters without a problem. More then 2 levels deep gets nasty though. Here’s how:

The html looks something like this:

<asp:Repeater ID="r1" runat="server" OnItemDataBound="r1_ItemDataBound">
<!-- top level repeater element template here -->
    <asp:Repeater ID="r2" runat="server" onitemdatabound="r2_ItemDataBound">
<!-- child repeater element template here -->

The codebehind looks like this:
    protected void r1_ItemDataBound(object sender, RepeaterItemEventArgs e) {
        Repeater r2 = (Repeater)e.Item.FindControl("r2");
        r2.DataSource = yourDataSourceHere; // you'll have to query for appropriate data

    protected void r2_ItemDataBound(object sender, RepeaterItemEventArgs e) {
        // do the same thing here for the 3rd nested repeater if you have a third, and so on

Method 4

<asp:Repeater ID="R1" runat="server">
        <asp:Repeater ID="R2" runat="server">

R1.ItemDataBound += (s, e) =>
    var r2 = e.Item.FindControl("R2") as Repeater;
    r2.DataSource = something;

Be aware that FindControl is not recursive, it will only get the children.

All methods was sourced from or, is licensed under cc by-sa 2.5, cc by-sa 3.0 and cc by-sa 4.0

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