Bug 33872 - ListView footer layout BindingContext not set
Summary: ListView footer layout BindingContext not set
Status: RESOLVED FIXED
Alias: None
Product: Forms
Classification: Xamarin
Component: Forms ()
Version: 1.4.4
Hardware: PC Windows
: --- normal
Target Milestone: ---
Assignee: Bugzilla
URL:
Depends on:
Blocks:
 
Reported: 2015-09-10 23:58 UTC by Simon Taylor
Modified: 2016-04-13 19:17 UTC (History)
6 users (show)

Tags:
Is this bug a regression?: ---
Last known good build:

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Status:
RESOLVED FIXED

Description Simon Taylor 2015-09-10 23:58:18 UTC
In the code below the Command and IsVisible bindings of "moreButton" do not work without explicitly setting the BindingContext of the list footer in OnBindingContextChanged. Tested on iOS.


    public class BankBranchListView : PopupFrame, IPopupView
    {
        public Button CancelButton { get; protected set; }

        private Layout _FooterLayout;

        public BankBranchListView(Branding branding)
            : base(branding, false)
        {
            var layout = new StackLayout
            {
                Style = branding.Styles.PageLayoutStyle,
                BackgroundColor = branding.Colors.PrimaryBackground
            };

            var header = new PageHeaderView(branding, AppResources.Description_BankBranchSelect);
            layout.Children.Add(header);

            var moreButton = new Button
            {
                Text = AppResources.ButtonLabel_More,
                HorizontalOptions = LayoutOptions.FillAndExpand
            };
            moreButton.SetBinding<BankBranchSearchViewModel>(Button.CommandProperty, v => v.LoadMoreCommand);
            moreButton.SetBinding<BankBranchSearchViewModel>(Button.IsVisibleProperty, v => v.Model.BSBNumber,
                                                        BindingMode.Default, new IsNullOrEmptyConverter());

            this.CancelButton = new Button
            {
                Text = AppResources.ButtonLabel_Cancel,
                HorizontalOptions = LayoutOptions.FillAndExpand
            };

            this._FooterLayout = new StackLayout
            {
                HorizontalOptions = LayoutOptions.FillAndExpand,
                Children = { moreButton, this.CancelButton }
            };

            var list = new CommandableListView
            {
                ItemTemplate = new DataTemplate(() => new PaddedDetailStringModelCell<BankBranchModel>(branding, false)),
                Footer = this._FooterLayout,
                HasUnevenRows = true
            };
            list.SetBinding<BankBranchSearchViewModel>(CommandableListView.ItemSelectCommandProperty, v => v.SelectBranchCommand);
            list.SetBinding<BankBranchSearchViewModel>(ListView.ItemsSourceProperty, v => v.Collection);

            layout.Children.Add(list);

            this.View = layout;
        }

        protected override void OnBindingContextChanged()
        {
            base.OnBindingContextChanged();

            this._FooterLayout.BindingContext = this.BindingContext;
        }
Comment 1 Paul DiPietro [MSFT] 2015-09-12 19:11:58 UTC
It seems there are external elements related to the sample you provided, here; if you could kindly create a reproduction project isolating this issue in question, it would be much appreciated in helping the team to investigate it.
Comment 2 Simon Taylor 2015-09-24 00:30:26 UTC
ListView needs an OnBindingContextChanged() implementation like below. The base OnBindingContextChanged() implementation only applies to elements in LogicalChildren, which the header and footer aren't.

  
        protected override void OnBindingContextChanged()
        {
            base.OnBindingContextChanged();

            var bindableHeader = this.Header as BindableObject;
            if (bindableHeader != null)
            {
                BindableObject.SetInheritedBindingContext(bindableHeader, this.BindingContext);
            }

            var bindableFooter = this.Footer as BindableObject;
            if (bindableFooter != null)
            {
                BindableObject.SetInheritedBindingContext(bindableFooter, this.BindingContext);
            }
        }