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Using Telerik's RadMenu to handle Roles

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Eric Wise

Posts: 126
Nickname: ewise
Registered: Apr, 2005

Eric Wise is a senior .NET consultant.

Using Telerik's RadMenu to handle Roles

Posted: Oct 18, 2005 5:40 AM

This post originated from an RSS feed registered with .NET Buzz by Eric Wise.
Original Post: Using Telerik's RadMenu to handle Roles Feed Title: Eric Wise Feed URL: /error.htm?aspxerrorpath=/blogs/eric.wise/rss.aspx Feed Description: Business & .NET	Latest .NET Buzz Posts Latest .NET Buzz Posts by Eric Wise Latest Posts From Eric Wise

My company has been a customer of Telerik for about 6 months now, and we've been nothing but happy with the service and support we've gotten from them and the continuous improvement of quality in their controls. I highly recommend checking them out.

Anyways, recently I was asked whether I could implement some role based security for displaying the items of a telerik menu so here is how I wired it up programatically.

Step 1: Create XML File

The first step was to create an xml file with the format and fields I needed for the menu items. Instead of using the group xml codes like in the telerik samples, I settled for a parent/child id relationship. So the end result is xml items with itemId, parentId (if null it's a top level item), navigateurl, text, target, and roles. Note that the item and parent id's aren't numbers, they must be strings. Like so:

<Item>

<menuItemID>i1</menuItemID>

<menuText>Distribute Inventory</menuText>

</Item>

<Item>

<menuItemID>i2</menuItemID>

<parentItem>i1</parentItem>

<menuText>Overall</menuText>

<navigateURL></navigateURL>

<target></target>

<roles></roles>

</Item>

<Item>

<menuItemID>i3</menuItemID>

<parentItem>i1</parentItem>

<menuText>By Individual</menuText>

<navigateURL></navigateURL>

<target></target>

<roles></roles>

</Item>

// etc

</MainMenu>

Step 2: Load and Cache the dataset/handle roles.

Since the menu structure will be accessed fairly frequently, it makes sense to cache it. Also, we need a function to check the roles since if the role tag is blank we need to handle that as "public". Note that you could delimit multiple roles into this tag but that is beyond the scope of this sample. For simplicity, we will use the dataset's ReadXML method. Notice that we are setting up a relation to link up the parent/child ids.

    Private Function CheckRole(ByVal roles As String)
        If roles = "" Then Return True
        Return context.User.IsInRole(roles)
    End Function
 
    Private Function GetMenuItems() As DataSet
        Dim ds As DataSet
 
        If Not IsNothing(Cache("MenuItems")) Then
            ds = CType(Cache.Get("MenuItems"), DataSet)
        Else
            ds = New DataSet
            ds.ReadXml(MapPath("~\XML\MainMenu.xml"))
            ds.Relations.Add("ItemRelation", ds.Tables(0).Columns("menuItemID"), ds.Tables(0).Columns("parentItem"))
            Cache.Add("MenuItems", ds, Nothing, DateTime.Now.AddHours(4), Nothing, Caching.CacheItemPriority.AboveNormal, Nothing)
        End If
 
        Return ds
    End Function

Step 3: Create a method for building a menu item from a datarow

Since we'll be walking the dataset and grabbing menu item information from datarows, we need a method to handle parsing the data. Simple enough:

    Private Sub CreateItem(ByRef item As MenuItem, ByRef dbRow As DataRow)
        item.Text = Convert.ToString(dbRow("menuText"))
        item.ID = Convert.ToString(dbRow("MenuItemID"))
 
        If Not IsDBNull(dbRow("navigateURL")) Then
            item.Href = Convert.ToString(dbRow("navigateURL"))
        End If
 
        If Not IsDBNull(dbRow("target")) Then
            item.Target = Convert.ToString(dbRow("target"))
        End If
    End Sub

Step 4: Loop all the top level items

Remember I said the top level items are items where the parentid is null. We need to loop the dataset and find all the parent items, when a parent item is found we need to load its child items.

    Protected Sub GenerateMainMenu()
        Dim addItem As Boolean
        Dim ds As DataSet = GetMenuItems()
 
        'Setup Menu
        Dim topGroup As New MenuGroup(RadMenu1)
        topGroup.Flow = PresentationDirection.Horizontal
        topGroup.ExpandDirection = ExpandDirection.Down
        RadMenu1.RootGroup = topGroup
 
        For Each dbRow As DataRow In ds.Tables(0).Rows
            addItem = False
            'Top level rows have a null parentItem
            'We will catch all the top items then query their children to build the menu
            If dbRow.IsNull("parentItem") Then
                If Not IsDBNull(dbRow("roles")) Then
                    addItem = CheckRole(dbRow("roles"))
                Else
                    addItem = True
                End If
            End If
 
            If addItem Then
                Dim item As New MenuItem(topGroup)
                CreateItem(item, dbRow)
                RecursivelyPopulate(dbRow, item)
                topGroup.AddItem(item)
            End If
        Next dbRow
    End Sub

Step 5: Recursively Populate the Child Items

The final step is to write the RecursivelyPopulate method which will take a parent item and query the dataset to see if there are child rows, if there are it will wire them up and then pass them through the same function (so it will go down multiple levels indefinitely). Here's the code:

    Private Sub RecursivelyPopulate(ByRef parentRow As DataRow, ByRef parentItem As MenuItem)
        Dim childRow As DataRow
        Dim addItem As Boolean
        Dim childGroup As MenuGroup
 
        For Each childRow In parentRow.GetChildRows("ItemRelation")
            addItem = False
 
            'instantiate group if necessary, we're doing it in the loop since we only want the group if there are child items
            If IsNothing(childGroup) Then
                childGroup = New MenuGroup(parentItem)
                childGroup = parentItem.AddChildGroup()
                childGroup.Flow = PresentationDirection.Vertical
            End If
 
            If Not IsDBNull(childRow("roles")) Then
                addItem = CheckRole(childRow("roles"))
            Else
                addItem = True
            End If
 
            If addItem Then
                Dim item As New MenuItem(childGroup)
                CreateItem(item, childRow)
                RecursivelyPopulate(childRow, item)
                childGroup.AddItem(item)
            End If
        Next childRow
    End Sub

So you can see, Telerik's menu control is very flexible and even if you want to do some things outside the scope of their standard examples you can do so without much hassle!

Read: Using Telerik's RadMenu to handle Roles

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