Blazor网格绑定列(按字段名称) [英] Blazor Grid Bound Column by Field Name

问题描述

我正在研究一些付费网格组件，它们具有非常酷的绑定列"技术:

I'm studying some paid grid components and they have a pretty cool "Bound Column" technique:

<TelerikGrid Data=@GridData>
    <GridColumns>
        <GridColumn Field="TemperatureC" Title="Temp. C" />
        <GridColumn Field="Summary" />
    </GridColumns>
    <GridToolBar>
        <GridCommandButton Command="Add" Icon="add">Add Forecast</GridCommandButton>
    </GridToolBar>
</TelerikGrid>

<DxDataGrid Data="@DataSource">
    <DxDataGridColumn Field="@nameof(ProductFlat.Id)">
    </DxDataGridColumn>
    <DxDataGridColumn Field="@nameof(ProductFlat.Category)">
    </DxDataGridColumn>
</DxDataGrid>

我该如何实现?我想创建一个非常基本的表:

how can I achieve this? I want to create a very basic table:

<MyGrid DataSource=@MySource>
  <MyColumn Field="Id" Name="My Id" />
</MyGrid>

渲染:

<table class="table">
  <thead>
    <tr>
      <th scope="col">My Id</th>
    </tr>
  </thead>
  <tbody>
    <tr>
      <td>#1</td>
    </tr>
    <tr>
      <td>#2</td>
    </tr>
  </tbody>
</table>

推荐答案

这不是一个简单的解决方案，您应该了解Blazor如何使用组件.基本上，方法是在外部MyGrid组件上注册子级MyColumn模板"，然后通过一点反射来动态渲染网格.在下面，我发布准备复制，测试和学习的食谱.

It's not a trivial solution, you should to understand how Blazor works with components. Basically, the way, is to register children MyColumn "templates" on outer MyGrid component, then, render grid dynamically with a bit of reflection. Below I post the recipe ready for copy-paste, test and learn.

dotnet new blazorserver

步骤1:创建Pages/MyColumn.razor组件:

Step 1: Create Pages/MyColumn.razor component:

@code {
    [Parameter]
    public string Field { get; set; }

    [CascadingParameter]
    private MyGrid Parent { get; set; }    

    protected override void OnInitialized()
    {
        base.OnInitialized();        
        Parent.AddColumn(this); //register child into parent
    }
}

步骤2:创建Pages/MyGrid.razor组件:

Step 2: Create Pages/MyGrid.razor component:

<CascadingValue Value="this">
<table class="table">
    <tbody>
        @ChildContent
        @foreach (var item in DataSource)
        {
            @RowItem(item) 
        }
    </tbody>
</table>
</CascadingValue>

@code {
    [Parameter]
    public RenderFragment ChildContent { get; set; }

    [Parameter]
    public IEnumerable<object> DataSource { get; set; }

    List<MyColumn> Columns = new List<MyColumn>();
    public void AddColumn(MyColumn column)
    {
        Columns.Add(column);
        StateHasChanged();
    }

// Here the function to create each row dynamically:

    private RenderFragment RowItem(object row)
    {   
        int i = 0;
        return b =>          // create dynamically
        {
            b.OpenElement(++i, "tr");
            foreach(var column in Columns)
            {
                b.OpenElement(++i, "td");
                var val = row.GetType().GetProperty(column.Field)
                          .GetValue(row, null).ToString();                
                b.AddContent(++i,val);
                b.CloseElement();
            }
            b.CloseElement();
        };
    }
}

步骤3:在Pages/FetchData.razor

上使用网格

Step 3: Use your grid on Pages/FetchData.razor

@page "/fetchdata"

@using s.Data
@inject WeatherForecastService ForecastService

<h1>Weather forecast</h1>

<p>This component demonstrates fetching data from a service.</p>

@if (forecasts == null)
{
    <p><em>Loading...</em></p>
}
else
{
    <MyGrid DataSource=@forecasts>
       <MyColumn Field="Date"/>
       <MyColumn Field="Summary"/>
    </MyGrid>
}

@code {
    private WeatherForecast[] forecasts;

    protected override async Task OnInitializedAsync()
    {
        forecasts = await ForecastService.GetForecastAsync(DateTime.Now);
    }
}

结果:

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