c# - 如何从项目集合中选择特定项目？

Question

我正在使用 Windows Phone 的 DataBoundApp 模板，并且在模板中，selectedIndex 值从 MainPage 传递到 DetailsPage 以定义数据上下文...像这样:

    // When page is navigated to set data context to selected item in list
    protected override void OnNavigatedTo(NavigationEventArgs e)
    {
        string selectedIndex = "";
        if (NavigationContext.QueryString.TryGetValue("selectedItem", out selectedIndex))
        {
            int index = int.Parse(selectedIndex);
            DataContext = App.ViewModel.Items[index];
        }
    }

这是设置数据上下文的唯一方法还是我可以选择其中具有特定值的项目，例如，我想将数据上下文设置为具有 LineOne =“runtime seven”值的项目...

我该如何设置？

编辑:这些是 View 模型项

    public void LoadData()
    {
        // Sample data; replace with real data
        this.Items.Add(new ItemViewModel() { LineOne = "runtime one", LineTwo = "Maecenas praesent accumsan bibendum", LineThree = "Facilisi faucibus habitant inceptos interdum lobortis nascetur pharetra placerat pulvinar sagittis senectus sociosqu" });
        this.Items.Add(new ItemViewModel() { LineOne = "runtime two", LineTwo = "Dictumst eleifend facilisi faucibus", LineThree = "Suscipit torquent ultrices vehicula volutpat maecenas praesent accumsan bibendum dictumst eleifend facilisi faucibus" });
        this.Items.Add(new ItemViewModel() { LineOne = "runtime three", LineTwo = "Habitant inceptos interdum lobortis", LineThree = "Habitant inceptos interdum lobortis nascetur pharetra placerat pulvinar sagittis senectus sociosqu suscipit torquent" });
        this.Items.Add(new ItemViewModel() { LineOne = "runtime four", LineTwo = "Nascetur pharetra placerat pulvinar", LineThree = "Ultrices vehicula volutpat maecenas praesent accumsan bibendum dictumst eleifend facilisi faucibus habitant inceptos" });
        this.Items.Add(new ItemViewModel() { LineOne = "runtime five", LineTwo = "Maecenas praesent accumsan bibendum", LineThree = "Maecenas praesent accumsan bibendum dictumst eleifend facilisi faucibus habitant inceptos interdum lobortis nascetur" });
        this.Items.Add(new ItemViewModel() { LineOne = "runtime six", LineTwo = "Dictumst eleifend facilisi faucibus", LineThree = "Pharetra placerat pulvinar sagittis senectus sociosqu suscipit torquent ultrices vehicula volutpat maecenas praesent" });
        this.Items.Add(new ItemViewModel() { LineOne = "runtime seven", LineTwo = "Habitant inceptos interdum lobortis", LineThree = "Accumsan bibendum dictumst eleifend facilisi faucibus habitant inceptos interdum lobortis nascetur pharetra placerat" });
        this.Items.Add(new ItemViewModel() { LineOne = "runtime eight", LineTwo = "Nascetur pharetra placerat pulvinar", LineThree = "Pulvinar sagittis senectus sociosqu suscipit torquent ultrices vehicula volutpat maecenas praesent accumsan bibendum" });
        this.Items.Add(new ItemViewModel() { LineOne = "runtime nine", LineTwo = "Maecenas praesent accumsan bibendum", LineThree = "Facilisi faucibus habitant inceptos interdum lobortis nascetur pharetra placerat pulvinar sagittis senectus sociosqu" });
        this.Items.Add(new ItemViewModel() { LineOne = "runtime ten", LineTwo = "Dictumst eleifend facilisi faucibus", LineThree = "Suscipit torquent ultrices vehicula volutpat maecenas praesent accumsan bibendum dictumst eleifend facilisi faucibus" });
        this.Items.Add(new ItemViewModel() { LineOne = "runtime eleven", LineTwo = "Habitant inceptos interdum lobortis", LineThree = "Habitant inceptos interdum lobortis nascetur pharetra placerat pulvinar sagittis senectus sociosqu suscipit torquent" });
        this.Items.Add(new ItemViewModel() { LineOne = "runtime twelve", LineTwo = "Nascetur pharetra placerat pulvinar", LineThree = "Ultrices vehicula volutpat maecenas praesent accumsan bibendum dictumst eleifend facilisi faucibus habitant inceptos" });
        this.Items.Add(new ItemViewModel() { LineOne = "runtime thirteen", LineTwo = "Maecenas praesent accumsan bibendum", LineThree = "Maecenas praesent accumsan bibendum dictumst eleifend facilisi faucibus habitant inceptos interdum lobortis nascetur" });
        this.Items.Add(new ItemViewModel() { LineOne = "runtime fourteen", LineTwo = "Dictumst eleifend facilisi faucibus", LineThree = "Pharetra placerat pulvinar sagittis senectus sociosqu suscipit torquent ultrices vehicula volutpat maecenas praesent" });
        this.Items.Add(new ItemViewModel() { LineOne = "runtime fifteen", LineTwo = "Habitant inceptos interdum lobortis", LineThree = "Accumsan bibendum dictumst eleifend facilisi faucibus habitant inceptos interdum lobortis nascetur pharetra placerat" });
        this.Items.Add(new ItemViewModel() { LineOne = "runtime sixteen", LineTwo = "Nascetur pharetra placerat pulvinar", LineThree = "Pulvinar sagittis senectus sociosqu suscipit torquent ultrices vehicula volutpat maecenas praesent accumsan bibendum" });

        this.IsDataLoaded = true;
    }

我不想通过项目的索引号设置数据上下文，而是通过特定的项目值

Answer 1

只要你能给你正在搜索的值赋值，下面的就可以了。

string value = "runtime seven";

DataContext = App.ViewModel.Items.FirstOrDefault(item => item.LineOne == value);