ASP.NET Core Blazor 樣板化元件
注意
這不是這篇文章的最新版本。 如需目前版本,請參閱本文的 .NET 8 版本。
本文說明樣板化元件如何接受一或多個 UI 範本作為參數,然後將其用作元件轉譯邏輯的一部分。
樣板化元件
樣板化元件是接收一或多個 UI 範本作為參數的元件,可在元件的轉譯邏輯中使用。 藉由使用樣板化元件,您可建立更能重複使用的較高層級元件。 幾個範例包括:
- 資料表元件,可讓使用者指定資料表頁首、資料列和頁尾的範本。
- 清單元件,可讓使用者指定範本來轉譯清單中的項目。
樣板化元件是藉由指定類型為 RenderFragment 或 RenderFragment<TValue> 的一或多個元件參數來定義。 轉譯片段代表要轉譯的 UI 區段。 RenderFragment<TValue> 採用可在叫用轉譯片段時指定的型別參數。
注意
如需 RenderFragment 的詳細資訊,請參閱 ASP.NET Core Razor 元件。
樣板化元件通常會為泛型類型,如下列 TableTemplate
元件示範。 此範例中的泛型型別 <T>
用於轉譯 IReadOnlyList<T>
值,在此案例中,這是顯示寵物資料表的元件中的一系列寵物資料列。
TableTemplate.razor
:
@typeparam TItem
@using System.Diagnostics.CodeAnalysis
<table class="table">
<thead>
<tr>@TableHeader</tr>
</thead>
<tbody>
@foreach (var item in Items)
{
if (RowTemplate is not null)
{
<tr>@RowTemplate(item)</tr>
}
}
</tbody>
</table>
@code {
[Parameter]
public RenderFragment? TableHeader { get; set; }
[Parameter]
public RenderFragment<TItem>? RowTemplate { get; set; }
[Parameter, AllowNull]
public IReadOnlyList<TItem> Items { get; set; }
}
@typeparam TItem
@using System.Diagnostics.CodeAnalysis
<table class="table">
<thead>
<tr>@TableHeader</tr>
</thead>
<tbody>
@foreach (var item in Items)
{
if (RowTemplate is not null)
{
<tr>@RowTemplate(item)</tr>
}
}
</tbody>
</table>
@code {
[Parameter]
public RenderFragment? TableHeader { get; set; }
[Parameter]
public RenderFragment<TItem>? RowTemplate { get; set; }
[Parameter, AllowNull]
public IReadOnlyList<TItem> Items { get; set; }
}
@typeparam TItem
@using System.Diagnostics.CodeAnalysis
<table class="table">
<thead>
<tr>@TableHeader</tr>
</thead>
<tbody>
@foreach (var item in Items)
{
if (RowTemplate is not null)
{
<tr>@RowTemplate(item)</tr>
}
}
</tbody>
</table>
@code {
[Parameter]
public RenderFragment? TableHeader { get; set; }
[Parameter]
public RenderFragment<TItem>? RowTemplate { get; set; }
[Parameter, AllowNull]
public IReadOnlyList<TItem> Items { get; set; }
}
@typeparam TItem
<table class="table">
<thead>
<tr>@TableHeader</tr>
</thead>
<tbody>
@foreach (var item in Items)
{
<tr>@RowTemplate(item)</tr>
}
</tbody>
</table>
@code {
[Parameter]
public RenderFragment TableHeader { get; set; }
[Parameter]
public RenderFragment<TItem> RowTemplate { get; set; }
[Parameter]
public IReadOnlyList<TItem> Items { get; set; }
}
@typeparam TItem
<table class="table">
<thead>
<tr>@TableHeader</tr>
</thead>
<tbody>
@foreach (var item in Items)
{
<tr>@RowTemplate(item)</tr>
}
</tbody>
</table>
@code {
[Parameter]
public RenderFragment TableHeader { get; set; }
[Parameter]
public RenderFragment<TItem> RowTemplate { get; set; }
[Parameter]
public IReadOnlyList<TItem> Items { get; set; }
}
使用樣板化元件時,可以使用符合參數名稱的子項目來指定範本參數。 在下列範例中,<TableHeader>...</TableHeader>
和 <RowTemplate>...<RowTemplate>
為 TableTemplate
元件的 TableHeader
和 RowTemplate
提供 RenderFragment<TValue> 範本。
當您想要指定隱含子系內容的內容參數名稱時,請在元件元素上指定 Context
屬性 (不含任何包裝子矽元素)。 在下列範例中,Context
屬性會出現在 TableTemplate
元素上,並套用至所有 RenderFragment<TValue> 範本參數。
Pets1.razor
:
@page "/pets-1"
<PageTitle>Pets 1</PageTitle>
<h1>Pets Example 1</h1>
<TableTemplate Items="pets" Context="pet">
<TableHeader>
<th>ID</th>
<th>Name</th>
</TableHeader>
<RowTemplate>
<td>@pet.PetId</td>
<td>@pet.Name</td>
</RowTemplate>
</TableTemplate>
@code {
private List<Pet> pets = new()
{
new Pet { PetId = 2, Name = "Mr. Bigglesworth" },
new Pet { PetId = 4, Name = "Salem Saberhagen" },
new Pet { PetId = 7, Name = "K-9" }
};
private class Pet
{
public int PetId { get; set; }
public string? Name { get; set; }
}
}
@page "/pets1"
<h1>Pets</h1>
<TableTemplate Items="pets" Context="pet">
<TableHeader>
<th>ID</th>
<th>Name</th>
</TableHeader>
<RowTemplate>
<td>@pet.PetId</td>
<td>@pet.Name</td>
</RowTemplate>
</TableTemplate>
@code {
private List<Pet> pets = new()
{
new Pet { PetId = 2, Name = "Mr. Bigglesworth" },
new Pet { PetId = 4, Name = "Salem Saberhagen" },
new Pet { PetId = 7, Name = "K-9" }
};
private class Pet
{
public int PetId { get; set; }
public string? Name { get; set; }
}
}
@page "/pets1"
<h1>Pets</h1>
<TableTemplate Items="pets" Context="pet">
<TableHeader>
<th>ID</th>
<th>Name</th>
</TableHeader>
<RowTemplate>
<td>@pet.PetId</td>
<td>@pet.Name</td>
</RowTemplate>
</TableTemplate>
@code {
private List<Pet> pets = new()
{
new Pet { PetId = 2, Name = "Mr. Bigglesworth" },
new Pet { PetId = 4, Name = "Salem Saberhagen" },
new Pet { PetId = 7, Name = "K-9" }
};
private class Pet
{
public int PetId { get; set; }
public string? Name { get; set; }
}
}
@page "/pets1"
<h1>Pets</h1>
<TableTemplate Items="pets" Context="pet">
<TableHeader>
<th>ID</th>
<th>Name</th>
</TableHeader>
<RowTemplate>
<td>@pet.PetId</td>
<td>@pet.Name</td>
</RowTemplate>
</TableTemplate>
@code {
private List<Pet> pets = new()
{
new Pet { PetId = 2, Name = "Mr. Bigglesworth" },
new Pet { PetId = 4, Name = "Salem Saberhagen" },
new Pet { PetId = 7, Name = "K-9" }
};
private class Pet
{
public int PetId { get; set; }
public string Name { get; set; }
}
}
@page "/pets1"
<h1>Pets</h1>
<TableTemplate Items="pets" Context="pet">
<TableHeader>
<th>ID</th>
<th>Name</th>
</TableHeader>
<RowTemplate>
<td>@pet.PetId</td>
<td>@pet.Name</td>
</RowTemplate>
</TableTemplate>
@code {
private List<Pet> pets = new List<Pet>
{
new Pet { PetId = 2, Name = "Mr. Bigglesworth" },
new Pet { PetId = 4, Name = "Salem Saberhagen" },
new Pet { PetId = 7, Name = "K-9" }
};
private class Pet
{
public int PetId { get; set; }
public string Name { get; set; }
}
}
或者,您可使用 RenderFragment<TValue> 子系元素上的 Context
屬性來變更參數名稱。 在下列範例中,Context
是設定於 RowTemplate
,而不是 TableTemplate
:
Pets2.razor
:
@page "/pets-2"
<PageTitle>Pets 2</PageTitle>
<h1>Pets Example 2</h1>
<TableTemplate Items="pets">
<TableHeader>
<th>ID</th>
<th>Name</th>
</TableHeader>
<RowTemplate Context="pet">
<td>@pet.PetId</td>
<td>@pet.Name</td>
</RowTemplate>
</TableTemplate>
@code {
private List<Pet> pets = new()
{
new Pet { PetId = 2, Name = "Mr. Bigglesworth" },
new Pet { PetId = 4, Name = "Salem Saberhagen" },
new Pet { PetId = 7, Name = "K-9" }
};
private class Pet
{
public int PetId { get; set; }
public string? Name { get; set; }
}
}
@page "/pets2"
<h1>Pets</h1>
<TableTemplate Items="pets">
<TableHeader>
<th>ID</th>
<th>Name</th>
</TableHeader>
<RowTemplate Context="pet">
<td>@pet.PetId</td>
<td>@pet.Name</td>
</RowTemplate>
</TableTemplate>
@code {
private List<Pet> pets = new()
{
new Pet { PetId = 2, Name = "Mr. Bigglesworth" },
new Pet { PetId = 4, Name = "Salem Saberhagen" },
new Pet { PetId = 7, Name = "K-9" }
};
private class Pet
{
public int PetId { get; set; }
public string? Name { get; set; }
}
}
@page "/pets2"
<h1>Pets</h1>
<TableTemplate Items="pets">
<TableHeader>
<th>ID</th>
<th>Name</th>
</TableHeader>
<RowTemplate Context="pet">
<td>@pet.PetId</td>
<td>@pet.Name</td>
</RowTemplate>
</TableTemplate>
@code {
private List<Pet> pets = new()
{
new Pet { PetId = 2, Name = "Mr. Bigglesworth" },
new Pet { PetId = 4, Name = "Salem Saberhagen" },
new Pet { PetId = 7, Name = "K-9" }
};
private class Pet
{
public int PetId { get; set; }
public string? Name { get; set; }
}
}
@page "/pets2"
<h1>Pets</h1>
<TableTemplate Items="pets">
<TableHeader>
<th>ID</th>
<th>Name</th>
</TableHeader>
<RowTemplate Context="pet">
<td>@pet.PetId</td>
<td>@pet.Name</td>
</RowTemplate>
</TableTemplate>
@code {
private List<Pet> pets = new()
{
new Pet { PetId = 2, Name = "Mr. Bigglesworth" },
new Pet { PetId = 4, Name = "Salem Saberhagen" },
new Pet { PetId = 7, Name = "K-9" }
};
private class Pet
{
public int PetId { get; set; }
public string Name { get; set; }
}
}
@page "/pets2"
<h1>Pets</h1>
<TableTemplate Items="pets">
<TableHeader>
<th>ID</th>
<th>Name</th>
</TableHeader>
<RowTemplate Context="pet">
<td>@pet.PetId</td>
<td>@pet.Name</td>
</RowTemplate>
</TableTemplate>
@code {
private List<Pet> pets = new List<Pet>
{
new Pet { PetId = 2, Name = "Mr. Bigglesworth" },
new Pet { PetId = 4, Name = "Salem Saberhagen" },
new Pet { PetId = 7, Name = "K-9" }
};
private class Pet
{
public int PetId { get; set; }
public string Name { get; set; }
}
}
RenderFragment<TValue> 類型的元件引數具有名為 context
的隱含參數可供使用。 在下列範例中,未設定 Context
。 @context.{PROPERTY}
提供寵物值給範本,其中 {PROPERTY}
是 Pet
屬性:
Pets3.razor
:
@page "/pets-3"
<PageTitle>Pets 3</PageTitle>
<h1>Pets Example 3</h1>
<TableTemplate Items="pets">
<TableHeader>
<th>ID</th>
<th>Name</th>
</TableHeader>
<RowTemplate>
<td>@context.PetId</td>
<td>@context.Name</td>
</RowTemplate>
</TableTemplate>
@code {
private List<Pet> pets = new()
{
new Pet { PetId = 2, Name = "Mr. Bigglesworth" },
new Pet { PetId = 4, Name = "Salem Saberhagen" },
new Pet { PetId = 7, Name = "K-9" }
};
private class Pet
{
public int PetId { get; set; }
public string? Name { get; set; }
}
}
@page "/pets3"
<h1>Pets</h1>
<TableTemplate Items="pets">
<TableHeader>
<th>ID</th>
<th>Name</th>
</TableHeader>
<RowTemplate>
<td>@context.PetId</td>
<td>@context.Name</td>
</RowTemplate>
</TableTemplate>
@code {
private List<Pet> pets = new()
{
new Pet { PetId = 2, Name = "Mr. Bigglesworth" },
new Pet { PetId = 4, Name = "Salem Saberhagen" },
new Pet { PetId = 7, Name = "K-9" }
};
private class Pet
{
public int PetId { get; set; }
public string? Name { get; set; }
}
}
@page "/pets3"
<h1>Pets</h1>
<TableTemplate Items="pets">
<TableHeader>
<th>ID</th>
<th>Name</th>
</TableHeader>
<RowTemplate>
<td>@context.PetId</td>
<td>@context.Name</td>
</RowTemplate>
</TableTemplate>
@code {
private List<Pet> pets = new()
{
new Pet { PetId = 2, Name = "Mr. Bigglesworth" },
new Pet { PetId = 4, Name = "Salem Saberhagen" },
new Pet { PetId = 7, Name = "K-9" }
};
private class Pet
{
public int PetId { get; set; }
public string? Name { get; set; }
}
}
@page "/pets3"
<h1>Pets</h1>
<TableTemplate Items="pets">
<TableHeader>
<th>ID</th>
<th>Name</th>
</TableHeader>
<RowTemplate>
<td>@context.PetId</td>
<td>@context.Name</td>
</RowTemplate>
</TableTemplate>
@code {
private List<Pet> pets = new()
{
new Pet { PetId = 2, Name = "Mr. Bigglesworth" },
new Pet { PetId = 4, Name = "Salem Saberhagen" },
new Pet { PetId = 7, Name = "K-9" }
};
private class Pet
{
public int PetId { get; set; }
public string Name { get; set; }
}
}
@page "/pets3"
<h1>Pets</h1>
<TableTemplate Items="pets">
<TableHeader>
<th>ID</th>
<th>Name</th>
</TableHeader>
<RowTemplate>
<td>@context.PetId</td>
<td>@context.Name</td>
</RowTemplate>
</TableTemplate>
@code {
private List<Pet> pets = new List<Pet>
{
new Pet { PetId = 2, Name = "Mr. Bigglesworth" },
new Pet { PetId = 4, Name = "Salem Saberhagen" },
new Pet { PetId = 7, Name = "K-9" }
};
private class Pet
{
public int PetId { get; set; }
public string Name { get; set; }
}
}
使用泛型類型的元件時,可能的話會推斷類型參數。 不過,您可使用名稱符合類型參數的屬性來明確指定類型,這就是上述範例中的 TItem
:
Pets4.razor
:
@page "/pets-4"
<PageTitle>Pets 4</PageTitle>
<h1>Pets Example 4</h1>
<TableTemplate Items="pets" TItem="Pet">
<TableHeader>
<th>ID</th>
<th>Name</th>
</TableHeader>
<RowTemplate>
<td>@context.PetId</td>
<td>@context.Name</td>
</RowTemplate>
</TableTemplate>
@code {
private List<Pet> pets = new()
{
new Pet { PetId = 2, Name = "Mr. Bigglesworth" },
new Pet { PetId = 4, Name = "Salem Saberhagen" },
new Pet { PetId = 7, Name = "K-9" }
};
private class Pet
{
public int PetId { get; set; }
public string? Name { get; set; }
}
}
@page "/pets4"
<h1>Pets</h1>
<TableTemplate Items="pets" TItem="Pet">
<TableHeader>
<th>ID</th>
<th>Name</th>
</TableHeader>
<RowTemplate>
<td>@context.PetId</td>
<td>@context.Name</td>
</RowTemplate>
</TableTemplate>
@code {
private List<Pet> pets = new()
{
new Pet { PetId = 2, Name = "Mr. Bigglesworth" },
new Pet { PetId = 4, Name = "Salem Saberhagen" },
new Pet { PetId = 7, Name = "K-9" }
};
private class Pet
{
public int PetId { get; set; }
public string? Name { get; set; }
}
}
@page "/pets4"
<h1>Pets</h1>
<TableTemplate Items="pets" TItem="Pet">
<TableHeader>
<th>ID</th>
<th>Name</th>
</TableHeader>
<RowTemplate>
<td>@context.PetId</td>
<td>@context.Name</td>
</RowTemplate>
</TableTemplate>
@code {
private List<Pet> pets = new()
{
new Pet { PetId = 2, Name = "Mr. Bigglesworth" },
new Pet { PetId = 4, Name = "Salem Saberhagen" },
new Pet { PetId = 7, Name = "K-9" }
};
private class Pet
{
public int PetId { get; set; }
public string? Name { get; set; }
}
}
@page "/pets4"
<h1>Pets</h1>
<TableTemplate Items="pets" TItem="Pet">
<TableHeader>
<th>ID</th>
<th>Name</th>
</TableHeader>
<RowTemplate>
<td>@context.PetId</td>
<td>@context.Name</td>
</RowTemplate>
</TableTemplate>
@code {
private List<Pet> pets = new()
{
new Pet { PetId = 2, Name = "Mr. Bigglesworth" },
new Pet { PetId = 4, Name = "Salem Saberhagen" },
new Pet { PetId = 7, Name = "K-9" }
};
private class Pet
{
public int PetId { get; set; }
public string Name { get; set; }
}
}
@page "/pets4"
<h1>Pets</h1>
<TableTemplate Items="pets" TItem="Pet">
<TableHeader>
<th>ID</th>
<th>Name</th>
</TableHeader>
<RowTemplate>
<td>@context.PetId</td>
<td>@context.Name</td>
</RowTemplate>
</TableTemplate>
@code {
private List<Pet> pets = new List<Pet>
{
new Pet { PetId = 2, Name = "Mr. Bigglesworth" },
new Pet { PetId = 4, Name = "Salem Saberhagen" },
new Pet { PetId = 7, Name = "K-9" }
};
private class Pet
{
public int PetId { get; set; }
public string Name { get; set; }
}
}
其他資源
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https://aka.ms/ContentUserFeedback。
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