Building your first .NET Core app

This tutorial will show you how to create an ASP.NET Core MVC app from scratch and use it to display content from your Kentico Kontent project. If you're new to ASP.NET Core MVC, you might want to take the Microsoft Getting started with ASP.NET Core MVC tutorial first.

You'll use the Kentico Kontent boilerplate (in other words, a template for new applications with a few basic features built on top) and customize it to suit your needs. The template includes features such as simple fixed-time caching, the Delivery .NET SDK (for fetching content from your Kentico Kontent project), 404 error handling, logging, a sitemap.xml generator, and more.

You will learn to:

• Set up the app template
• Connect your Kentico Kontent project
• Add content type models
• Render Rich text elements
• Configure app features

Requirements

Make sure you have the following installed:

• .NET Core SDK 2.0.0 or newer
• An IDE (such as Visual Studio 2017) or the text editor of your choice

Preparing the app template

Open a command line, register the ASP.NET Core MVC with Kentico Cloud custom template within your .NET Core templates by running the following command.

shell
dotnet new --install "Kentico.Kontent.Boilerplate::*"
dotnet new --install "Kentico.Kontent.Boilerplate::*"

Now you can initialize a new app based on that template.

shell
dotnet new kentico-kontent-mvc --name "MyWebsite"
dotnet new kentico-kontent-mvc --name "MyWebsite"

Your new web app is ready. Navigate to its folder and run it.

shell
cd .\MyWebsite
dotnet run
cd .\MyWebsite
dotnet run

Your app will start and be available at http://localhost:5000. Open the address in your browser to view it.

Connecting the app to your project

Right now the app fetches content from the default Sample Project and displays a preview of 3 articles.

To connect the app to your own project:

1. In Kentico Kontent, choose Project settings  from the app menu.
2. Under Development, choose API keys.
3. Copy the Project ID.
4. In the app folder, open the appsettings.json file.
5. Replace the value of the ProjectId key with the ID of your project.
6. Save the changes.

When you now run the app again and open http://localhost:5000 in your browser, the app will work with data from the specified project.

Adding content type models

To make further app development easier, we recommend using the Kentico Kontent model generator for .NET to create strongly-typed models representing your content types. To learn more about this approach generally, see Using strongly typed models.

Your project will likely have other content types with different structure than the included sample models. This means you can safely overwrite the contents of the \Models\ContentTypes\ folder with your own models.

1. Generating models

First, clone the GitHub repository with the model generator to your drive.

shell
git clone https://github.com/Kentico/kontent-generators-net.git
git clone https://github.com/Kentico/kontent-generators-net.git

Next, in your command line, navigate to .\kontent-generators-net\src\KontentModelGenerator\ and use the dotnet run command with the following parameters:

• --projectid – specifies the ID of your Kentico Kontent project.
• --withtypeprovider – tells the generator to create the CustomTypeProvider class to support runtime type resolution.
• --structuredmodel – tells the generator to type Rich text elements as IRichTextContentobjects instead of strings.
• --outputdir – specifies where to store the generated models.
• --namespace – specifies the namespace of the generated models.

shell
# Sets the working directory
cd .\kontent-generators-net\src\KontentModelGenerator\

# Note: This overwrites existing files in the Models\ContentTypes folder
dotnet run --projectid "<YOUR_PROJECT_ID>" --withtypeprovider --structuredmodel --outputdir "<PATH_TO_YOUR_APP>\Models\ContentTypes" --namespace "MyWebsite.Models"
# Sets the working directory
cd .\kontent-generators-net\src\KontentModelGenerator\

# Note: This overwrites existing files in the Models\ContentTypes folder
dotnet run --projectid "<YOUR_PROJECT_ID>" --withtypeprovider --structuredmodel --outputdir "<PATH_TO_YOUR_APP>\Models\ContentTypes" --namespace "MyWebsite.Models"

The models are generated as partial classes. This means you can extend them in separate files and re-generate the models in the future without losing your custom code. If you'd like to learn more about the data types used for individual content elements, see Working with strongly typed models.

2. Mapping retrieved content to your models

Now, when you fetch content items from your project, you can map the returned data to a specific model.

C#
using Kentico.Kontent.Delivery;

// Initializes a content delivery client
IDeliveryClient client = DeliveryClientBuilder
      .WithProjectId("<YOUR_PROJECT_ID>")
      .Build();

// Retrieves 3 articles ordered by their post date
DeliveryItemListingResponse<Article> response = await client.GetItemsAsync<Article>(
    new EqualsFilter("system.type", "article"),
    new LimitParameter(3),
    new OrderParameter("elements.post_date", SortOrder.Descending)
);

// Sends the strongly-typed content items to a View
return View(response.Items)
using Kentico.Kontent.Delivery;

// Initializes a content delivery client
IDeliveryClient client = DeliveryClientBuilder
      .WithProjectId("<YOUR_PROJECT_ID>")
      .Build();

// Retrieves 3 articles ordered by their post date
DeliveryItemListingResponse<Article> response = await client.GetItemsAsync<Article>(
    new EqualsFilter("system.type", "article"),
    new LimitParameter(3),
    new OrderParameter("elements.post_date", SortOrder.Descending)
);

// Sends the strongly-typed content items to a View
return View(response.Items)

You can find the code in the HomeController controller.

3. Displaying your content

After that, you can access any of the content type's elements (as model properties) in the app's Views.

HTML
@model Article

<div class="body">
  <h2>@Model.Title</h2>

  <img src="@Model.TeaserImage.First().Url" class="img-responsive" alt="@Model.TeaserImage.First().Name"/>

  @Model.Summary
</div>
@model Article

<div class="body">
  <h2>@Model.Title</h2>

  <img src="@Model.TeaserImage.First().Url" class="img-responsive" alt="@Model.TeaserImage.First().Name"/>

  @Model.Summary
</div>

If you're using a different model, be sure to change the model declaration and individual properties.

Rendering Rich text elements

To render Rich text elements, use the Html.DisplayFor helper method in your Views.

C#
@* Renders content of a Rich text element (BodyCopy in an article) *@
@Html.DisplayFor(model => model.BodyCopy)
@* Renders content of a Rich text element (BodyCopy in an article) *@
@Html.DisplayFor(model => model.BodyCopy)

Right now, individual blocks of content in Rich text elements will be rendered using their default HTML representation, matching the content returned by the Delivery API. But you can also write your own representations of rich content.

Rendering rich content

To customize the way your app renders components, content items and inline images, you need to provide display templates for them:

• Components and content items – display template named <ModelName>.cshtml where the ModelName refers to the content type of the content item or component, for example, Tweet.cshtml.
• (Optional) Inline images – display template named InlineImage.cshtml.

For a more in-depth example, see Dealing with structure in rich text.

Resolving URLs

If your Rich text elements contain links to other content items, you need to tell your app how to form correct URLs.

To do this, open the Resolvers\CustomContentLinkUrlResolver.cs file in your app and add implementation to the following methods:

• ResolveLinkUrl – used when the linked content item is available.
• ResolveBrokenLinkUrl – used when the linked content item is not available.

Note that both methods must return strings.

See the example below and add more logic based on your content types.

C#
public string ResolveLinkUrl(ContentLink link)
{
    // Resolves links pointing to Article content items
    if (link.ContentTypeCodename.Equals(Article.Codename))
    {
        return $"/articles/{link.UrlSlug}";
    }

    // Add the rest of the resolver logic
}

public string ResolveBrokenLinkUrl()
{
    // Resolves URLs to unavailable content items
    return "/Error/404";
}
public string ResolveLinkUrl(ContentLink link)
{
    // Resolves links pointing to Article content items
    if (link.ContentTypeCodename.Equals(Article.Codename))
    {
        return $"/articles/{link.UrlSlug}";
    }

    // Add the rest of the resolver logic
}

public string ResolveBrokenLinkUrl()
{
    // Resolves URLs to unavailable content items
    return "/Error/404";
}

If you want to learn more about the way these resolvers work, see Resolving links to content items.

Configuring the app

The app template also includes a set of pre-configured features such as error handling, fixed-time caching, sitemap.xml generator, and others. You can configure most of these features in the Startup.cs file.

Error handling

When you run the app locally on your machine without specifying any environment-specific launch profile, the app will use a development profile. This means that if your app encounters an exception, it will be logged to the console and displayed directly in your browser.

In a production environment (that is when the app is run with a production profile), all errors are still logged, but a custom error page is displayed instead of the stack trace.

If you'd like to tweak the error handling and relevant error pages, see the following:

• The Configure method in the Startup class – specifies app behavior in different environments.
• The ErrorController controller – specifies what pages to display for specific HTTP status codes such as 404 Not Found.
• The views in the Views\Error folder – contain pages that are displayed when an error occurs in a production environment.

Caching

To use fewer Content API calls, the app employs a fixed-time caching mechanism and stores the retrieved content in its memory for 5 minutes. Without any caching, you would be making requests to the Delivery API with each page load. You can set a different time by changing the CacheTimeoutSeconds key in the appsettings.json file.

What's next?

The basic skeleton of your new app is now ready. We recommend you use it as a starting point and add more functionality where needed.

For example, you might find inspiration in the following:

• Our Sample .NET MVC application – includes examples of View Models and Display Templates.
• Combine your app with GraphQL using  the Apollo boilerplate.
• Learn about the ways to filter and sort the content you retrieve from your project.