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How to Use Partial Views in .NET Core

Partial views in ASP.NET Core are a powerful feature that allows developers to break down a large view into smaller, reusable components. This modular approach promotes cleaner, more maintainable code by enabling the reuse of UI elements across different views.

What is a Partial View?

A partial view is similar to a regular view but is designed to render a portion of the webpage. Unlike a full view, a partial view doesn't have a layout of its own and is intended to be rendered within a parent view. Partial views are especially useful for rendering dynamic content and reducing code duplication.

Benefits of Using Partial Views

  1. Reusability: Common UI components can be defined once and reused across multiple views.
  2. Separation of Concerns: Breaking down a large view into smaller components makes the code more manageable and easier to understand.
  3. Maintainability: Changes to a partial view are reflected wherever it is used, simplifying updates and maintenance.

Creating a Partial View


Step 1. Add a Partial View

To create a partial view in ASP.NET Core, right-click on the Views folder or a subfolder and select Add > New Item. Choose MVC View Page and name it with an underscore prefix (e.g., _PartialView.cshtml).

Example. Creating a partial view for displaying a list of products.

<!-- Views/Shared/_ProductList.cshtml -->
@model IEnumerable<Product>

<div class="product-list">
    @foreach (var product in Model)
    {
        <div class="product-item">
            <h3>@product.Name</h3>
            <p>Price: @product.Price</p>
        </div>
    }
</div>

Step 2. Render the Partial View

To render a partial view in a parent view, use the Partial method in the Razor syntax.

Example. Rendering the _ProductList partial view in a parent view.

<!-- Views/Home/Index.cshtml -->
@model IEnumerable<Product>

<h2>Product List</h2>
@Html.Partial("_ProductList", Model)

You can also use the PartialAsync method to render a partial view asynchronously.

@await Html.PartialAsync("_ProductList", Model)

Passing Data to Partial Views

Partial views can accept a model passed from the parent view. You can either pass the entire model or a subset of it.

Example. Passing a list of products to the _ProductList partial view.

@model IEnumerable<Product>

<h2>Product List</h2>
@Html.Partial("_ProductList", Model)

If you need to pass a different model, you can do so by specifying the model explicitly.

@Html.Partial("_ProductList", Model.Products)

Using View Components as an Alternative

While partial views are useful, ASP.NET Core also offers view components, which provide a more powerful way to encapsulate reusable rendering logic. View components are similar to partial views but can include more complex logic and are more akin to controllers.

Creating a View Component

  1. Create a View Component Class 
    public class ProductListViewComponent : ViewComponent
{
    private readonly IProductService _productService;

    public ProductListViewComponent(IProductService productService)
    {
        _productService = productService;
    }

    public async Task<IViewComponentResult> InvokeAsync()
    {
        var products = await _productService.GetProductsAsync();
        return View(products);
    }
}
  2. Create a View for the View Component
    Create a view for the view component in the Views/Shared/Components folder. 
    <!-- Views/Shared/Components/ProductList/Default.cshtml -->
@model IEnumerable<Product>

<div class="product-list">
    @foreach (var product in Model)
    {
        <div class="product-item">
            <h3>@product.Name</h3>
            <p>Price: @product.Price</p>
        </div>
    }
</div>
  3. Invoke the View Component
    Invoke the view component in a parent view using the Component method. 
    @await Component.InvokeAsync("ProductList")

Conclusion

Partial views in ASP.NET Core offer a convenient way to create reusable and maintainable UI components. By leveraging partial views, you can keep your views clean and organized, facilitating easier updates and better code management. Additionally, consider using view components for more complex rendering logic, as they provide greater flexibility and separation of concerns.


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