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Working with Sass in an ASP.NET Core application

2023-06-02T06:50:59+01:00

Sass (Syntactically Awesome Style Sheets) is a is a scripting language that is used to generate cascading style sheets (CSS files). Its syntax is very similar to CSS itself, but it supports the use of variables, nesting, mixins and selector inheritance, none of which are available in CSS itself. However, these features help you to organise and maintain your web application's styles. In this article, I look at the steps required to incorporate and configure Sass in your ASP.NET Core project in both Visual Studio, and VS Code.

Why doesn't my ASP.NET Core 7 web app launch on HTTPS?

2023-03-20T01:37:26+00:00

Up until .NET 7, when you use the dotnet run command to run your ASP.NET Core Razor Pages (or MVC) app, the built-in Ketstrel web server would listen on two URLs, one with a http protocol and another that uses the https protocol. This behaviour is documented in many places (including my book) so it might come as a surprise when you run your new .NET 7 app from the command line and it is only available on an http binding. Something changed in .NET 7. What is it and how do you test your .NET 7 web app under https?

Executing async operations onchange in Blazor

2023-02-15T09:32:57+00:00

Blazor's two-way databinding model is extremely powerful, but sometimes it can get in the way of what you want to do. For example, you might want to execute an asynchronous operation such as remote validation when a value changes in a textbox. Perhaps you want to check instantaneously that the value - a username maybe - doesn't already exist in a database before you accept a new registration. You cannot add an onchange event handler if you already have a value bound to the element, so what can you do? In this article, I look at solutions for both HTML elements and EditForm input validation components up to an including .NET 7, and a new feature released in .NET 7.0.1.

Exploring generating PDF files from HTML in ASP.NET Core

2022-11-30T01:45:51+00:00

Back in 2008, I wrote a series of articles about using iTextSharp to generate PDF files in an ASP.NET application. I still use iTextSharp in a large MVC 5 application that I'm in the process of migrating to ASP.NET Core. The version I use is very old (4.1.6), and the API is very low level so it takes quite a while to write the code required to generate even a moderately complex PDF. Ideally I need a replacement for the new application that can generate PDF files purely from HTML, which is an API I'm much more comfortable with. This ancient version of iTextSharp doesn't support HTML as a source of content. In this article, I consider some alternatives.

A reusable generic autocomplete component for Blazor

2022-11-17T01:14:18+00:00

In my last article, I looked at building a simple autocomplete component within a Blazor WebAssembly application that fetches data dynamically from a database via an API depending on what the user enters into an input. It works nicely but it has not been designed to be reusable. In this article, I look at the steps required to convert the component so that it can be plugged in anywhere within an application and work with any kind of data.

Simple Autocomplete for Blazor

2022-11-08T08:49:37+00:00

One of the things I really like about Blazor is how often it is easy to implement features in your application that, if needed in a server-side application, would have you testing your JavaScript-fu or reaching for a third party component. One example is an autocomplete component that fetches live data from a database that matches that which a user enters into a form control and changes as the user types. In this article, I'll show how to build such a component for a Blazor WebAssembly app and style it like a dropdown.

Resize images before uploading in Blazor Web Assembly

2022-10-31T02:03:44+00:00

So, you allow users to upload images to the server from your Blazor WASM app, but you want to constrain the actual dimensions of the image for some reason. Rather than ask the user to edit the image prior to uploading, you decide to to take care of applying this requirement within the application. And you further decide to do any resizing in the browser prior to uploading so that the resulting upload is smaller and you don't have to waste server resources on the procedure. In this article, I take a look at how to do that, and how to get the dimensions of an image file.

Incrementally Migrating an ASP.NET Framework application to Razor Pages

2022-10-11T01:41:10+01:00

Do you have a huge .NET framework application (Web forms, MVC) that relies on authentication and/or System.Web types that you would ideally like to migrate to .NET Core, but just don't have the bandwidth to put everything on hold while you rewrite the entire application on a new framework? If so, you might be interested in an exciting new project from Microsoft - SystemWebAdapters for ASP.NET Core - that enables you to incrementally migrate your old application, endpoint by endpoint.

Strongly Typed Middleware in ASP.NET Core

2022-08-24T12:30:51+01:00

Most ASP.NET Core developers are familiar with the traditional way to author middleware classes which is based on conventions. The vast majority of examples out there feature the convention-based approach. But there is also a strongly typed approach available which is based on implementing the IMiddleware interface. This seems to be one of ASP.NET Core's best kept secrets, so I thought I'd pull the curtains back and let some light shine on it.

Using Minimal APIs in ASP.NET Core Razor Pages

2021-12-14T01:33:30+00:00

If you are using ASP.NET Core Razor Pages to develop your web application, you have already decided that the majority of your HTML will be generated on the server. Nevertheless, chances are that you will want to introduce some client side operations into the application to improve its user friendliness in places. If those operations involve data, you will probably want to work with JSON. From .NET 6, you can use a simplified minimal request handler API that works with JSON by default.

Razor Pages Startup in .NET 6

2021-10-08T08:34:09+01:00

When you create a new web app using .NET 6 (from the new RC1 templates), you might notice something is missing. There is no Startup class. What happened to it? And how do you configure your new .NET 6 web app?

I am writing a book about Razor Pages

2021-11-24T03:35:38+00:00

Just over three years go, when Razor Pages was first launched, I had a number of questions from people asking whether I was going to write a book about the Razor Pages framework. I guess they asked me because Razor Pages appeared to be a natural successor to the old ASP.NET Web Pages framework, and I had written a book about that. Also, I was regularly blogging at the time about all the good things you could do with Razor Pages. The answer then was No, primarily because I was working on my own tutorial/documentation site for Razor Pages - learnrazorpages.com.

CSS Isolation In Razor Pages

2023-03-23T09:03:57+00:00

CSS isolation was introduced in .NET 5 for Blazor components. Now it's coming to Razor Pages (and MVC views) in .NET 6, due to be released in November this year. Here's a quick look at how CSS isolation works in Razor Pages and the kind of problem that it's designed to solve.

Implementing a Custom TypeConverter In Razor Pages

2020-11-24T06:34:21+00:00

In my most recent article, I showed how to create a custom model binder to bind an ISO 8601 string representation of a week of the year to a DateTime type in a Razor Pages application. The custom model binder leant heavily on the existing infrastructure that binds strings to simple types. Custom model binders are the correct solution if you want to bind to simple types, but if you want to bind to a complex type, the recommendation is to implement a TypeConverter according to the offical docs. But the docs don't provide an example that shows how to do that in the context of model binding. So here's one.

Implementing a Custom Model Binder In Razor Pages

2020-11-10T03:28:04+00:00

In Razor Pages, model binding is the process that maps data from an HTTP request to simple PageModel properties or handler parameters. Incoming data can be included in a request as posted form values, query string values or route data. The default collection of model binders cover every simple .NET data type.. But sometimes they are not enough, and you need to add your own implementation.

Working with Dates And Times in Razor Pages Forms

2021-06-29T06:23:08+01:00

When working with dates and times in a Razor Pages form, you need to render a suitable control based in the task requirement. Prior to HTML5, developers largely depended on third party date picker libraries. Now, a variety of native browser options exist, although they enjoy varied support across modern browsers. These include options for managing the date and time, just the date or time, and for working with the month or week of the year.

Display Images in Bootstrap Carousel using Razor Pages and Entity Framework

2020-06-19T03:37:02+01:00

This short article shows how to display images stored in a database in a Razor Pages application using the Bootstrap Carousel and Entity Framework Core.

Razor Pages And Bootstrap - Lazy Loading Tabs

2020-06-10T12:34:23+01:00

Tabbed interfaces are a great way for managing the presentation of large amounts of information into separate panels, where each panel's data makes sense on its own, and only one panel is viewable at a time. The tabs in a browser are a great example of this. From a Razor Pages developer's point of view, tabs are particularly useful for controlling the display of complex data in Line Of Business applications.

Razor Pages And Bootstrap - Modal Master Details

2023-10-10T07:03:52+01:00

This is the first in a series of posts exploring how to use some of the components provided by Bootstrap within a database-driven Razor Pages web application. In this article, I look at using the Bootstrap Modal in a Master/Details scenario, to display the details of the selected record in a master list.

Razor Pages Localisation - SEO-friendly URLs

2020-01-07T07:39:46+00:00

This is the fourth article in a series that explores various aspects of localisation in ASP.NET Core Razor Pages applications. This article concentrates on the SEO aspects of localisation as they pertain to URL management, and how to utilise the RouteDataRequestCultureProvider to help you manage that.