如何將搜索應用于MVVM(WPF)中的串列，而無需每次都呼叫串列值？

首先，我是 MVVM 的新手，但如果我遺漏了這一點，請隨時糾正我。

我正在使用 MVVM 社區工具包的 WPF 應用程式。我的應用程式架構看起來更像這樣：

1. 我有簡單的Model包含一些基本屬性

public class Package : ObservableObject
    {
        private string id;
        public string Id
        {
            get => id;
            set => SetProperty(ref id, value);
        }

        private string name;
        public string Name
        {
            get => name;
            set => SetProperty(ref name, value);
        }

        private string version;
        public string Version
        {
            get => version;
            set => SetProperty(ref version, value);
        }

        private string summary;
        public string Summary
        {
            get => summary;
            set => SetProperty(ref summary, value);
        }
}

2. 還有ViewModel哪里有 IList<Package>屬性和AsyncRelayCommand它呼叫的程序中，得到輸出和更新屬性。

class MainWindowViewModel : ObservableObject
    {
        public AsyncRelayCommand StartProcessCommand { get; }
        public MainWindowViewModel()
        {
            
            StartProcessCommand = new AsyncRelayCommand(StartProcess, CanStartProcess);
            
        }
        
        private async Task StartProcess()
        {
            
           //Start process, collect the output and set the PackageList property
        }

        private IList<Package> packagesList;

        public IList<Package> PackagesList
        {
            get => packagesList;
            set => SetProperty(ref packagesList, value);
        }
 }

3. 然后有一個View系結完成的地方，如下所示：

<ListView ItemsSource="{Binding PackagesList, Mode=OneWay, UpdateSourceTrigger=PropertyChanged}">
               
                <ListView.View>
                    <GridView>
                        <GridViewColumn Header="Id" DisplayMemberBinding="{Binding Id}"/>
                        <GridViewColumn Header="Name" DisplayMemberBinding="{Binding Name}"/>
                        <GridViewColumn Header="Version" DisplayMemberBinding="{Binding Version}" />
                        <GridViewColumn Header="Summary" DisplayMemberBinding="{Binding Summary}"/>
                    </GridView>
                </ListView.View>
            </ListView>

以及呼叫 RelayCommand（異步）的按鈕。

這是我面臨的問題和問題

I would like to apply the Search TextBox to dynamically search the result of the IList<Package>, for this purpose I have create a SearchText in the ViewModel which updates the IList<Package> property on the PropertyChanged event. The problem is that my property is changing and I would like to not recall it every time from the process.

1. Create a list
2. Search the list and present it in a View
3. In case I'm removing my searchText value it's still showing the list from the point 1

What will be best approach to achieve this?

This is so far where I got to but works only once, filter the list but not returning to previous list:

public void SearchItem()
        {
            PackagesList = packagesList.Where(package => package.Id == SearchText).ToList();

        }

private string? searchText;
        public string? SearchText
        {
            get => searchText;
            set
            {
                SetProperty(ref searchText, value);
                SearchItem();
            }
            
        }

uj5u.com熱心網友回復：

在里面MainWindowViewModel創建另一個屬性IList<Package>并呼叫它ResultList

    private IList<Package> ResultList { get; set;} // Add Result list
    private IList<Package> packagesList;

    public IList<Package> PackagesList
    {
        get => packagesList;
        set => SetProperty(ref packagesList, value);
    }

將您的 ItemsSource 系結設定為ResultList。

        <ListView ItemsSource="{Binding ResultList, Mode=OneWay, UpdateSourceTrigger=PropertyChanged}">
           
            <ListView.View>
                <GridView>
                    <GridViewColumn Header="Id" DisplayMemberBinding="{Binding Id}"/>
                    <GridViewColumn Header="Name" DisplayMemberBinding="{Binding Name}"/>
                    <GridViewColumn Header="Version" DisplayMemberBinding="{Binding Version}" />
                    <GridViewColumn Header="Summary" DisplayMemberBinding="{Binding Summary}"/>
                </GridView>
            </ListView.View>
        </ListView>

任何時候你設定你的PackagesList，你也設定了ResultList。現在當它開始搜索時，你做這樣的事情

public void SearchItem()
{
    ResultList = packagesList.Where(package => package.Id == SearchText).ToList();
}

uj5u.com熱心網友回復：

根據你的說法，你想在洗掉文本后顯示所有資料？如果是這樣，你可以試試這個

public void SearchItem()
{   
    PackagesList = packagesList.Where(package => package.Id == SearchText || null == SearchText).ToList();
}

標籤：c# wpf search mvvm propertychanged

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