Htmx.Net
This is a package designed to add server side helper methods for HttpRequest and HttpResponse. This makes working with htmx server-side concepts simpler. You should also consider reading about Hyperscript, an optional companion project for HTMX.
Htmx Extension Methods
Getting Started
Install the Htmx NuGet package to your ASP.NET Core project.
dotnet add package HtmxHttpRequest
Using the HttpRequest, we can determine if the request was initiated by Htmx on the client.
httpContext.Request.IsHtmx()This can be used to either return a full page response or a partial page render.
// in a Razor Page
return Request.IsHtmx()
? Partial("_Form", this)
: Page();We can also retrieve the other header values htmx might set.
Request.IsHtmx(out var values);Read more about the other header values on the official documentation page.
HttpResponse
We can set Http Response headers using the Htmx extension method, which passes an action and HtmxResponseHeaders object.
Response.Htmx(h => {
h.PushUrl("/new-url")
.WithTrigger("cool")
});Read more about the HTTP response headers at the official documentation site.
Triggering Client-Side Events
You can trigger client side events with HTMX using the HX-Trigger header. Htmx.Net provides a WithTrigger helper method to configure one or more events that you wish to trigger.
Response.Htmx(h => {
h.WithTrigger("yes")
.WithTrigger("cool", timing: HtmxTriggerTiming.AfterSettle)
.WithTrigger("neat", new { valueForFrontEnd= 42, status= "Done!" }, timing: HtmxTriggerTiming.AfterSwap);
});Htmx.TagHelpers
Getting Started
Install the Htmx.TagHelpers NuGet package to your ASP.NET Core project. Targets .NET Core 3.1+ projects.
dotnet add package Htmx.TagHelpersMake the Tag Helpers available in your project by adding the following line to your _ViewImports.cshtml:
@addTagHelper *, Htmx.TagHelpersYou'll generally need URL paths pointing back to your ASP.NET Core backend. Luckily, Htmx.TagHelpers mimics the url generation included in ASP.NET Core. This makes linking HTMX with your ASP.NET Core application a seamless experience.
<div hx-target="this">
<button hx-get
hx-page="Index"
hx-page-handler="Snippet"
hx-swap="outerHtml">
Click Me (Razor Page w/ Handler)
</button>
</div>
<div hx-target="this">
<button hx-get
hx-controller="Home"
hx-action="Index"
hx-route-id="1">
Click Me (Controller)
</button>
</div>
<div hx-target="this">
<button hx-post
hx-route="named">
Click Me (Named)
</button>
</div>Htmx.Config
An additional htmx-config tag helper is included that can be applied to a meta element in your page's head that makes creating HTMX configuration simpler. For example, below we can set the historyCacheSize, default indicatorClass, and whether to include ASP.NET Core's anti-forgery tokens as an additional element on the HTMX configuration.
<!DOCTYPE html>
<html lang="en">
<head>
<meta name="htmx-config"
historyCacheSize="20"
indicatorClass="htmx-indicator"
includeAspNetAntiforgeryToken="true"
/>
<!-- additional elements... -->
</head>The resulting HTML will be.
<!DOCTYPE html>
<html lang="en">
<head>
<meta name="htmx-config" content='{"indicatorClass":"htmx-indicator","historyCacheSize":20,"antiForgery":{"formFieldName":"__RequestVerificationToken","headerName":"RequestVerificationToken","requestToken":"<token>"}}' />
<!-- additional elements... -->
</head>HTMX and Anti-forgery Tokens
You can set the attribute includeAspNetAntiforgerToken on the htmx-config element. Then you'll need to include this additional JavaScript in your web application. We include the attribute __htmx_antiforgery to track the event listener was added already. This keeps us from accidentally re-registering the event listener.
if (!document.body.attributes.__htmx_antiforgery) {
document.addEventListener("htmx:configRequest", evt => {
let httpVerb = evt.detail.verb.toUpperCase();
if (httpVerb === 'GET') return;
let antiForgery = htmx.config.antiForgery;
if (antiForgery) {
// already specified on form, short circuit
if (evt.detail.parameters[antiForgery.formFieldName])
return;
if (antiForgery.headerName) {
evt.detail.headers[antiForgery.headerName]
= antiForgery.requestToken;
} else {
evt.detail.parameters[antiForgery.formFieldName]
= antiForgery.requestToken;
}
}
});
document.addEventListener("htmx:afterOnLoad", evt => {
if (evt.detail.boosted) {
const parser = new DOMParser();
const html = parser.parseFromString(evt.detail.xhr.responseText, 'text/html');
const selector = 'meta[name=htmx-config]';
const config = html.querySelector(selector);
if (config) {
const current = document.querySelector(selector);
// only change the anti-forgery token
const key = 'antiForgery';
htmx.config[key] = JSON.parse(config.attributes['content'].value)[key];
// update DOM, probably not necessary, but for sanity's sake
current.replaceWith(config);
}
}
});
document.body.attributes.__htmx_antiforgery = true;
}You can access the snippet in two ways. The first is to use the HtmxSnippet static class in your views.
<script>
@Html.Raw(HtmxSnippets.AntiforgeryJavaScript)
</script>
A simpler way is to use the HtmlExtensions class that extends IHtmlHelper.
@Html.HtmxAntiforgeryScript()
This html helper will result in a <script> tag along with the previously mentioned JavaScript. Note: You can still register multiple event handlers for htmx:configRequest, so having more than one is ok.
Note that if the hx-[get|post|put] attribute is on a <form ..> tag, the ASP.NET Tag Helpers will add the Anti-forgery Token as an input element and you do not need to further configure your requests as above. You could also use hx-include pointing to a form, but this all comes down to a matter of preference.
Additionally, and the recommended approach is to use the HtmxAntiforgeryScriptEndpoint, which will let you map the JavaScript file to a specific endpoint, and by default it will be _htmx/antiforgery.js.
app.UseAuthorization();
// registered here
app.MapHtmxAntiforgeryScript();
app.MapRazorPages();
app.MapControllers();You can now configure this endpoint with caching, authentication, etc. More importantly, you can use the script in your head tag now by applying the defer tag, which is preferred to having JavaScript at the end of a body element.
<head>
<meta charset="utf-8"/>
<meta name="viewport" content="width=device-width, initial-scale=1.0"/>
<meta
name="htmx-config"
historyCacheSize="20"
indicatorClass="htmx-indicator"
includeAspNetAntiforgeryToken="true"/>
<title>@ViewData["Title"] - Htmx.Sample</title>
<link rel="stylesheet" href="~/lib/bootstrap/dist/css/bootstrap.min.css"/>
<link rel="stylesheet" href="~/css/site.css" asp-append-version="true"/>
<script src="~/lib/jquery/dist/jquery.min.js" defer></script>
<script src="~/lib/bootstrap/dist/js/bootstrap.bundle.min.js" defer></script>
<script src="https://unpkg.com/htmx.org@@1.9.2" defer></script>
<!-- this uses the static value in a script tag -->
<script src="@HtmxAntiforgeryScriptEndpoints.Path" defer></script>
</head>License
Copyright Β© 2022 Khalid Abuhakmeh
Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the βSoftwareβ), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions:
The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software.
THE SOFTWARE IS PROVIDED βAS ISβ, WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.