循环遍历数据透视项并检查标题 wp8

Question

I have a pivot called "infra" I want to loop through all pivot items in infra and check the header value of each item in order to determine which page I should load for the user. My code below doesn't seem to work.

protected override void OnNavigatedTo(NavigationEventArgs e)
    {

        string headerName;
        if (NavigationContext.QueryString.TryGetValue("goto", out headerName))
        {

            foreach (PivotItem pi in infra.Items)
            {
                if (pi.Header.ToString() == headerName)
                    infra.SelectedItem = pi;
            }

        }
        base.OnNavigatedTo(e);
    }

Any ideas on how I can do this a variation on the code above worked fine for a panorama but I had to change to a pivot.

Additional Info: I am dynamically creating buttons based on some JSON on a panorama page, I am also dynamically creating pivot items based on some other JSON. The buttons should take the user to a specific Pivot Item. A buttons "x:name" attribute is the same as a pivot items header.

Answer 1

I'm not sure why you are trying to compare index (name of a variable strItemIndex ) to Header . You can easily switch PivotItem by using SelecedIndex:

protected override void OnNavigatedTo(NavigationEventArgs e)
{
    string strItemIndex;
    if (NavigationContext.QueryString.TryGetValue("goto", out strItemIndex))
        infra.SelectedIndex = int.Parse(strItemIndex);
    base.OnNavigatedTo(e);
}

EDIT - after comments and OP's edit:

If you need to recognize your PivotItem with Header, then your code looks ok. It can be optimalized a little:

string headerName;
PivotItem itemToNavigate = null;
if (NavigationContext.QueryString.TryGetValue("goto", out headerName))
    itemToNavigate = infra.Items.FirstOrDefault(x => (x as PivotItem).Header.ToString() == headerName) as PivotItem;
if (itemToNavigate != null) infra.SelectedItem = item;
else infra.SelectedIndex = 0; // navigate to default one (remember to check first if there are any items)

Where can be problems:

• check if your infra is filled with items when the method is being invoked,
• check how headers look like - do they contain a right string after ToString() ,
• check if headerName pulled out from query string is all right.

All the three steps you should be able to check via debugging.

Answer 2

The way Romasz suggested you is correct way, but you can also use below to solve your problem.

protected override void OnNavigatedTo(NavigationEventArgs e)
    {

        string headerName;
        if (NavigationContext.QueryString.TryGetValue("goto", out headerName))
        {

            for (var i = 0; i < infra.Items.Count; i++)
            {
                if (((PivotItem)infra.Items[i]).Header == headerName)
                {
                    infra.SelectedIndex = i;
                    break;
                }
            }

        }
        base.OnNavigatedTo(e);
    }