Markdown Editor component for Blazor

Few weeks ago, I created a package for a Markdown Editor component for Blazor with very basic functionalities. After a couple of months of work, finally, I created a very nice Markdown Editor component based on EasyMDE flexible and rich of functionalities for Blazor WebAssembly and Blazor Server with .NET6.

The full source code of the component is available on GitHub. In the same repository, there is a demo project and another project for the integration between the Markdown Editor for Blazor and the API for uploading images.

How to use

First, in your Blazor project, add the NuGet package called PSC.Blazor.Components.MarkdownEditor. Then, add the Markdown Editor to your _Imports.razor

@using PSC.Blazor.Components.MarkdownEditor 
@using PSC.Blazor.Components.MarkdownEditor.EventsArgs

Now, in your index.html or host.html add those lines:

<link href="/_content/PSC.Blazor.Components.MarkdownEditor/css/easymde.min.css" rel="stylesheet" />

<script src="/_content/PSC.Blazor.Components.MarkdownEditor/js/easymde.min.js"></script>
<script src="/_content/PSC.Blazor.Components.MarkdownEditor/js/markdownEditor.js"></script>

Remember that jQuery is also required. The component contains the EasyMDE script version 2.15.0. Obviously, you can add this script in your project but if you use the script in the component, you are sure it works fine and all functionalities are tested.

Add MarkdownEditor in a page

Now, in a Razor page, we can add the component with these lines

<div class="col-md-12">
    <MarkdownEditor Value="@markdownValue" 
                    ValueChanged="@OnMarkdownValueChanged"
                    ValueHTMLChanged="@OnMarkdownValueHTMLChanged" />

    <hr />

    <h3>Result</h3>
    @((MarkupString)markdownHtml)
</div>

@code {
    string markdownValue = "#Markdown Editor\nThis is a test";
    string markdownHtml;

    protected override void OnInitialized()
    {
        markdownHtml = Markdig.Markdown.ToHtml(markdownValue ?? string.Empty);
        base.OnInitialized();
    }

    Task OnMarkdownValueChanged(string value)
    {
        return Task.CompletedTask;
    }

    Task OnMarkdownValueHTMLChanged(string value)
    {
        markdownHtml = value;
        return Task.CompletedTask;
    }
}

So, the result is a nice Markdown Editor like in the following screenshot. This is a screenshot from the demo in this repository.

Code explained

So, the initial text for the Markdown Editor is coming from the markdownValue that is a string containing Markdown text. For every change in the editor, the Value changes and the component raises an event, in this case OnMarkdownValueChanged: this event receives the Markdown text as a value.

From here, I can process with my procedure the Markdown text to obtain the HTML but I want to simplify this step. So, the component converts the Markdown text in a HTML and raises the event ValueHTMLChanged.

Documentation

The Markdown Editor for Blazor has an estensive collection of properties to map all the functionalities in the JavaScript version. In this repository, there are 2 projects:

• MarkdownEditorDemo is a Blazor Web Assembly project that contains 2 pages: Index.razor where I show how to use the component with the basic functions and Upload.razor that shows how to cope with the image upload. To test the upload, the project MarkdownEditorDemo.Api must run
• MarkdownEditorDemo.Api this is an ASP.NET Core WebApi (.NET6) how to implement a proper API for uploading images. For more details, I wrote a post about Uploading image with .NET.

Properties

Events

Upload file

Now, the Markdown Editor for Blazor can take care of uploading a file and add the relative Markdown code in the editor. For that, the property UploadImage has to set to true. Also, the upload API must be specified in the property ImageUploadEndpoint.

In some cases, the API requires an authentication. The properties ImageUploadAuthenticationSchema and ImageUploadAuthenticationToken allow you to pass the correct schema and token to use in the call.

Those values will be added to the HttpClient POST request in the header. Only if both properties are not null, they will be added to the header.

So, the result is quite nice and you can see the Markdown Editor for Blazor in action in the following screenshot. How you can see, I drag an image on the editor and immediately the upload process starts. When the API returns then URL for the image, the editor adds a new Markdown text for the image.

How to create the API

Now, if you want to allow users to upload pictures via the Markdown Editor for Blazor, the property UploadImage must set to true. Then, the endpoint for the API must be declared via the property ImageUploadEndpoint.

The Markdown Editor has JavaScript under the cover and this can cause same complications. For this reason, I managed in the JavaScript code to have the uploaded imaged encoded in Base64. Then, a C# function takes care to upload the file to the specified API. This API must return a 200 HTTP code and, as a content, the URL of the uploaded image.

It seems easy but I took a lot of time to figure out how to do it. So, I created the post Upload/Download Files Using HttpClient to explain in details how to create the required API.

The full source code of the component is available on GitHub.

Toolbar icons

Below are the built-in toolbar icons (only some of which are enabled by default), which can be reorganized however you like. “Name” is the name of the icon, referenced in the JS. “Action” is either a function or a URL to open. “Class” is the class given to the icon. “Tooltip” is the small tooltip that appears via the title="" attribute. Note that shortcut hints are added automatically and reflect the specified action if it has a key bind assigned to it (i.e. with the value of action set to bold and that of tooltip set to Bold, the final text the user will see would be “Bold (Ctrl-B)”).

Additionally, you can add a separator between any icons by adding "|" to the toolbar array.

Keyboard shortcuts

The Markdown Editor component for Blazor comes with an array of predefined keyboard shortcuts, but they can be altered with a configuration option. The list of default ones is as follows:

Wrap up

In conclusion, this is a new Markdown Editor for Blazor, with a lot of functionalities, flexible and with image upload. I hope you like it and will use it. It you need help or for suggestion, please comment below or in the Forum.

Other Blazor components

• DataTable for Blazor: DataTable component for Blazor WebAssembly and Blazor Server
• Markdown editor for Blazor: This is a Markdown Editor for use in Blazor. It contains a live preview as well as an embedded help guide for users.
• Modal dialog for Blazor: Simple Modal Dialog for Blazor WebAssembly
• PSC.Extensions: A lot of functions for .NET6 in a NuGet package that you can download for free. We collected in this package functions for everyday work to help you with claim, strings, enums, date and time, expressions…
• Quill for Blazor: Quill Component is a custom reusable control that allows us to easily consume Quill and place multiple instances of it on a single page in our Blazor application
• Segment for Blazor: This is a Segment component for Blazor Web Assembly and Blazor Server
• Tabs for Blazor: This is a Tabs component for Blazor Web Assembly and Blazor Server

More examples and documentation

• Write a reusable Blazor component
• Getting Started With C# And Blazor
• Setting Up A Blazor WebAssembly Application
• Working With Blazor Component Model
• Secure Blazor WebAssembly With IdentityServer4
• Blazor Using HttpClient With Authentication
• InputSelect component for enumerations in Blazor
• Use LocalStorage with Blazor WebAssembly
• Modal Dialog component for Blazor
• Create Tooltip component for Blazor
• Consume ASP.NET Core Razor components from Razor class libraries | Microsoft Docs