RazorView/RazorPages related data

Question

I have some data specific to each razor view and and i do not want to hard-code it to each view. So, i want to add view related compile-time data to each view.

• Custom attributes do not work for me because we cannot add custom attributes to razor views.
• I do not want to re-fetch/populate this data from the data source(dictionary etc.) for each request or when view reached.

So, is there any way to attach data to each view at once throughout the life time of asp.net application?

Note Actually i want to add scripts/styles generated by webpack for each view statically. Their links include hash values so they change when source scripts/styles change. So, i just want to get them added to each view only once(equivalent to typing them into view) through out the asp.net application, not every time a view loads.

Answer 1

I created a demo application for you here.

You will want to use your appsettings.json file, and inject your settings into your view.

In my appsettings.json I added a section called "ViewConfiguration":

"ViewConfiguration": {
    "ExampleKey": "ExampleValue"
}

Your various values will need to go into your ViewConfiguration section.

For example where I have ExampleKey, you will use a generic name like "IndexPageStyleSheet", and where I have ExampleValue, you will need to update each release with the new stylesheet path. This will only need to be updated when the filename changes.

I then created a ViewConfiguration class which stores all of the values from the appsettings.json file.

You will need to create one property per configuration line, and ensure that the name of the property matches the name of the key in your appsettings.json.

For example where my appsettings.json has ExampleKey, my ViewConfiguration class also has an ExampleKey.

public class ViewConfiguration {
    public string ExampleKey { get; set; }
}

In your Startup.cs you will need to tell your IOC container to load your configuration values into your configuration object.

In my Startup.cs, my ConfigureServices method loads my "ExampleValue" into ViewConfiguration.ExampleKey automatically.

    public void ConfigureServices(IServiceCollection services) {
        // This line is the magic that loads the values from appsettings.json into a ViewConfiguration object.
        services.Configure<ViewConfiguration>(Configuration.GetSection("ViewConfiguration"));

        services.AddMvc();
    }

Now, in my _ViewImports.cshtml I inject my ViewConfiguration object so that I don't need to inject it into every single page. This can be anywhere in the _ViewImports.cshtml file. If you only want to inject specific configuration per folder, you can create a new _ViewImports.cshtml file per folder and inject different configuration objects into each one. It's flexible.

@using Microsoft.Extensions.Options;

@* Please rename this variable to something more appropriate to your application: *@
@inject IOptions<ViewConfiguration> InjectedViewConfig

Now, in any page, you can simply reference the property in your ViewConfiguration object.

For example in my Index.cshtml, I reference the ViewConfiguration.ExampleKey property by referencing the strongly typed property on InjectedViewConfig.Value, and it outputs "ExampleValue" on the page.

This value could just as easily be injected into a script or css link tag as the name of a file. It's very flexible.

<h1>Value: @InjectedViewConfig.Value.ExampleKey</h1>

With further research, you will be able to inject these values from any configuration source, such as Azure application settings or Azure Key Vault. Please see this article for more details.

Answer 2

If you are using mvc, you can create models and add it into the views. Since you don't want to recreate for each view, you can create readonly variables.

static readonly MyModel ModelData = new MyModel { PropName = "Hello" };
public IActionResult Index () => View(ModelData);

In your view you can now strongly type the value. If you are looking to use MVVM, you can refer to ViewModel concept still exists in ASP.NET MVC Core?

Answer 3

Implementing IFileProvider and IFileInfo provides changing the contents of view at compile-time. So, we could replace and provide static data in views with a template engine(i.e. http://dotliquidmarkup.org/).

Check this; https://www.mikesdotnetting.com/article/301/loading-asp-net-core-mvc-views-from-a-database-or-other-location