Wpf listview/gridview: hiding repeated content

listviewwpf

I'm new to WPF and don't know how to implement what I need.

My problem:

I've got a data bound WPF gridview displaying the results of an SQL query.
Some of the columns present repeated data that I'd like to hide.
This:

occupancy   name       room
---------   ---------  -----
Occupied    Bob        1
Occupied    Ted        2
Available              3
Available              4

Should look like this:

occupancy   name       room
---------   ---------  -----
Occupied    Bob        1
            Ted        2
Available              3
                       4

My environment:

Using C# on .net 3.5. I've bound the listview to a dataview collection. I have a data template for the cells to control the formatting.

My tenative solution:

I thought I should apply a trigger to the template and change the properties to make the text empty on all rows after the first where the data is the same as the previous row.

When I setup the trigger can I perform this all in xaml or do I need to write code to access the previous row?

If it's in XAML how do you construct the binding string(s) to reference the columns in the current and previous rows of the dataview it's bound to? Will it choke on the first row since there is no previous row?

here's the template I'm working with:

<DataTemplate x:Key="Occupancy">
    <TextBlock Name="Occupancy" Text="{Binding Path=Occupancy}" TextAlignment="Left" />
    <DataTemplate.Triggers>
        <DataTrigger Binding="{Binding Path=Occupancy}">
            <DataTrigger.Value>Available</DataTrigger.Value>
            <Setter TargetName="Occupancy" Property="**{previous column's content}**" Value="**{current columns content}**"/>
        </DataTrigger>
    </DataTemplate.Triggers>
</DataTemplate>

Maybe use RelativeSource:PreviousData ??

If I have to write code does anyone know of a decent tutorial that would get me started?

Alternative solutions are ok, though I think a no-code style that I could apply to many columns would be the optimal solution.

Thanks for your time.

Jay

Best Answer

I've had a negative experience with the RelativeSource:PreviousData. It worked in ListBox, but in the list view I was getting an error “Cannot find previous element for use as RelativeSource because there is no parent in generated context.”

I finally gave up and enumerated rows myself (the idea was to use it to print row numbers).

In your situation, I'd use a ModelView with a list elements of which would point to corresponding and previous elements of your Model. So if previous and current have the same value in the corresponding property, ModelView's element would return null.

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package com.wilson.android.library;

/*
 Licensed to the Apache Software Foundation (ASF) under one or more
contributor license agreements.  See the NOTICE file
distributed with this work for additional information
regarding copyright ownership.  The ASF licenses this file
to you under the Apache License, Version 2.0 (the
"License"); you may not use this file except in compliance
with the License.  You may obtain a copy of the License at

http://www.apache.org/licenses/LICENSE-2.0

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software distributed under the License is distributed on an
"AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
KIND, either express or implied.  See the License for the
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under the License.
*/
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C# – Binding a WPF ComboBox to a custom list

You set the DisplayMemberPath and the SelectedValuePath to "Name", so I assume that you have a class PhoneBookEntry with a public property Name.

Have you set the DataContext to your ConnectionViewModel object?

I copied you code and made some minor modifications, and it seems to work fine. I can set the viewmodels PhoneBookEnty property and the selected item in the combobox changes, and I can change the selected item in the combobox and the view models PhoneBookEntry property is set correctly.

Here is my XAML content:

<Window x:Class="WpfApplication6.Window1"
        xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
        xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
        Title="Window1" Height="300" Width="300">
<Grid>
    <StackPanel>
        <Button Click="Button_Click">asdf</Button>
        <ComboBox ItemsSource="{Binding Path=PhonebookEntries}"
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                  SelectedValuePath="Name"
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</Grid>
</Window>

And here is my code-behind:

namespace WpfApplication6
{

    /// <summary>
    /// Interaction logic for Window1.xaml
    /// </summary>
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        {
            InitializeComponent();
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        private void Button_Click(object sender, RoutedEventArgs e)
        {
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    public class PhoneBookEntry
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        public string Name { get; set; }

        public PhoneBookEntry(string name)
        {
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        }

        public override string ToString()
        {
            return Name;
        }
    }

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    {
        public ConnectionViewModel()
        {
            IList<PhoneBookEntry> list = new List<PhoneBookEntry>();
            list.Add(new PhoneBookEntry("test"));
            list.Add(new PhoneBookEntry("test2"));
            _phonebookEntries = new CollectionView(list);
        }

        private readonly CollectionView _phonebookEntries;
        private string _phonebookEntry;

        public CollectionView PhonebookEntries
        {
            get { return _phonebookEntries; }
        }

        public string PhonebookEntry
        {
            get { return _phonebookEntry; }
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        private void OnPropertyChanged(string propertyName)
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    }
}

Edit: Geoffs second example does not seem to work, which seems a bit odd to me. If I change the PhonebookEntries property on the ConnectionViewModel to be of type ReadOnlyCollection, the TwoWay binding of the SelectedValue property on the combobox works fine.

Maybe there is an issue with the CollectionView? I noticed a warning in the output console:

System.Windows.Data Warning: 50 : Using CollectionView directly is not fully supported. The basic features work, although with some inefficiencies, but advanced features may encounter known bugs. Consider using a derived class to avoid these problems.

Edit2 (.NET 4.5): The content of the DropDownList can be based on ToString() and not of DisplayMemberPath, while DisplayMemberPath specifies the member for the selected and displayed item only.

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