## Giraffe.Htmx

This package enables server-side support for [htmx](https://htmx.org) within [Giraffe](https://giraffe.wiki) and ASP.NET's `HttpContext`.

**htmx version: 4.0.0-alpha6**

_Upgrading from v2.x: the [migration guide](https://four.htmx.org/migration-guide-htmx-4/) lists changes for v4. For this package, the `HX-Trigger` and `HX-Trigger-Name` headers are marked obsolete. They are replaced by `HX-Source`, which provides the triggering tag name and `id` attribute. The `HX-Prompt` header has also been marked as obsolete, as the `hx-prompt` attribute which generated its content has been removed._

_Obsolete elements will be removed in the first production v4 release._

### Setup

1. Install the package.
2. Prior to using the request header extension properties or the header-setting `HttpHandler`s, `open Giraffe.Htmx`.

### Use

To obtain a request header, using the `IHeaderDictionary` extension properties:

```fsharp
let myHandler : HttpHander =
    fun next ctx ->
        match ctx.Target with
        | Some elt -> ... // do something with id of the target element
        | None -> ... // no target element provided
```

To set a response header:

```fsharp
let myHandler : HttpHander =
    fun next ctx ->
        // some meaningful work
        withHxPushUrl "/some/new/url" >=> [other handlers]
```

The `HxSwap` module has constants to use for the `HX-Reswap` header. These may be extended with settle, show, and other qualifiers; see the htmx documentation for the `hx-swap` attribute for more information.

To load the package-provided htmx library without using Giraffe.ViewEngine, use `HtmxScript.local`.

### Learn

The naming conventions of this library were selected to mirror those provided by htmx. The header properties become `Hx*` on the `ctx.Request.Headers` object, and the response handlers are `withHx*` based on the header being set. The only part that does not line up is `withHxTrigger*` and `withHxTriggerMany`; the former set work with a single string (to trigger a single event with no arguments), while the latter set supports both arguments and multiple events.