Posts tagged “css”


November 29, 2021
  A Tour of myPrayerJournal v3: Bootstrap Integration

NOTE: This is the third post in a series; see the introduction for information on requirements and links to other posts in the series.

Many modern Single Page Application (SPA) frameworks include (or have plugins for) CSS transitions and effects. Combined with the speed of not having to do a full refresh, this is one of their best features. One might not think that a framework like htmx, which simply swaps out sections of the page, would have this; but if one were to think that, one would be wrong. Sadly, though, I did not utilize those aspects of htmx while I was migrating myPrayerJournal from v2 to v3; however, I will highlight the htmx way to do this in last section of this post.

myPrayerJournal v2 used a Vue plugin that provided Bootstrap v4 support; myPrayerJournal v3 uses Bootstrap v5. The main motivation I had to remain with Bootstrap was that I liked the actual appearance, and I know how it works. The majority of my “learning” on this project dealt with htmx; I did not want to add a UI redesign to the mix. Before we jump into the implementation, let me briefly explain the framework.

About Bootstrap

Bootstrap was originally called Twitter Bootstrap; it was the CSS framework that Twitter developed in their early iterations. It was, by far, the most popular framework at the time, and it was innovative in its grid layout system. Long before there was browser support for the styles that make layouts much easier to develop, and more responsive to differing screen sizes, Bootstrap’s grid layout and size breakpoints made it easy to build a website that worked for desktop, tablet, or phone. Of course, there is a limit to what you can do with styling, so Bootstrap also has a JavaScript library that augments these styles, enabling the interactivity to which the modern web user is accustomed.

Version 5 of Bootstrap continues this tradition; however, it brings in even more utility classes, and supports Flex layouts as well. It is a mature library that continues to be maintained, and the project’s philosophy seems to be “just enough” - it’s not going to do everything for everyone, but in the majority of cases, it has exactly what the developer needs. It is not a bloated library that needs tree-shaking to avoid a ridiculous download size.

It is, by far, the largest payload in the initial page request:

  • Bootstrap - 48.6 kB (CSS is 24.8 kB; JavaScript is 23.8 kB, deferred until after render)
  • htmx - 11.8 kB
  • myPrayerJournal - 4.4 kB (CSS is 1.2 kB, JavaScript is 3.2 kB)

However, this gets the entire style and script, and allows us to use their layouts and interactive components. But, how do we get that interactivity from the server?

Hooking in to the htmx Request Pipeline

htmx provides several events to which an application can listen. In myPrayerJournal v3, I used htmx:afterOnLoad because I did not need the new content to be swapped in yet when the function fired. There are afterSwap and afterSettle events which will fire once those events have occurred, if you need to defer processing until those are complete.

There are two different Bootstrap script-driven components myPrayerJournal uses; let’s take a look at toasts.

A Toast to Via htmx

Toasts are pop-up notifications that appear on the screen, usually for a short time, then fade out. In some cases, particularly if the toast is alerting the user to an error, it will stay on the screen until the user dismisses it, usually by clicking an “x” in the upper right-hand corner (even if the developer used a Mac!). Bootstrap provides a host of options for their toast component; for our uses, though, we will:

  • Place toasts in the bottom right-hand corner;
  • Allow multiple toasts to be visible at once;
  • Auto-hide success toasts; require others to be dismissed manually.

There are several different aspects that make this work.

The Toaster

Just like IRL toast comes out of a toaster, our toasts need a place from which to emerge. In the prior post, I mentioned that the footer does not get reloaded when a “page” request is made. There is also an element above the footer that also remains across these requests - defined here as the “toaster” (my term, not Bootstrap’s).

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/// Element used to display toasts
let toaster =
div [ _ariaLive "polite"; _ariaAtomic "true"; _id "toastHost" ] [
div [ _class "toast-container position-absolute p-3 bottom-0 end-0"; _id "toasts" ] []
]

This renders two empty divs with the appropriate style attributes; toasts placed in the #toasts div will display as we want them to.

Showing the Toast

Bootstrap provides data- attributes that can make toasts appear; however, since we are creating these in script, we need to use their JavaScript functions. The message coming from the server has the format TYPE|||The message. Let’s look at the showToast function (the largest custom JavaScript function in the entire application):

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const mpj = {
// ...
showToast (message) {
const [level, msg] = message.split("|||")

let header
if (level !== "success") {
const heading = typ => `<span class="me-auto"><strong>${typ.toUpperCase()}</strong></span>`

header = document.createElement("div")
header.className = "toast-header"
header.innerHTML = heading(level === "warning" ? level : "error")

const close = document.createElement("button")
close.type = "button"
close.className = "btn-close"
close.setAttribute("data-bs-dismiss", "toast")
close.setAttribute("aria-label", "Close")
header.appendChild(close)
}

const body = document.createElement("div")
body.className = "toast-body"
body.innerText = msg

const toastEl = document.createElement("div")
toastEl.className = `toast bg-${level === "error" ? "danger" : level} text-white`
toastEl.setAttribute("role", "alert")
toastEl.setAttribute("aria-live", "assertlive")
toastEl.setAttribute("aria-atomic", "true")
toastEl.addEventListener("hidden.bs.toast", e => e.target.remove())
if (header) toastEl.appendChild(header)

toastEl.appendChild(body)
document.getElementById("toasts").appendChild(toastEl)
new bootstrap.Toast(toastEl, { autohide: level === "success" }).show()
},
// ...
}

Here’s what’s going on in the code above:

  • Line 4 splits the level from the message
  • Lines 6-20 (let header) create a header and close button if the message is not a success
  • Lines 22-24 (const body) create the body div with attributes Bootstrap’s styling expects
  • Lines 26-30 (const toastEl) create the div that will contain the toast
  • Line 31 adds an event handler to remove the element from the DOM once the toast is hidden
  • Lines 32 and 34 add the optional header and mandatory body to the toast div
  • Line 35 adds the toast to the page (within the toasts inner div defined above)
  • Line 36 initializes the Bootstrap JavaScript component, auto-hiding on success, and shows the toast

(If you’ve never used JavaScript to create elements that are added to an HTML document, this probably looks weird and verbose; if you have, you look at it and think “well, they’re not wrong…”)

So, we have our toaster, we know how to put bread notifications in it - but how do we get the notifications from the server?

Receiving the Toast

The code to handle this is part of the htmx:afterOnLoad handler:

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htmx.on("htmx:afterOnLoad", function (evt) {
const hdrs = evt.detail.xhr.getAllResponseHeaders()
// Show a message if there was one in the response
if (hdrs.indexOf("x-toast") >= 0) {
mpj.showToast(evt.detail.xhr.getResponseHeader("x-toast"))
}
// ...
})

This looks for a custom HTTP header of X-Toast (all headers are lowercase from that xhr call), and if it’s found, we pass the value of that header to the function above. This check occurs after every htmx network request, so there is nothing special to configure; “page” requests are not the only requests capable of returning a toast notification.

There is one more part; how does the toast get to the browser?

Sending the Toast

The last paragraph gave it away; we set a header on the response. This seems straightforward, and is in most cases; but once again, POST-Redirect-GET (P-R-G) complicates things. Here are the final two lines of the successful path of the request update handler:

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Messages.pushSuccess ctx "Prayer request updated successfully" nextUrl
return! seeOther nextUrl next ctx

If we set a message in the response header, then redirect (remember that XMLHttpRequest handles redirects silently), the header gets lost in the redirect. Here, Messages.pushSuccess places the success message (and return URL) in a dictionary, indexed by the user’s ID. Within the function that renders every result (partial, “page”-like, or full results), this dictionary is checked for a message and URL, and if one exists, it includes it. (If it is returned to the function below, it has already been removed from the dictionary.)

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/// Send a partial result if this is not a full page load (does not append no-cache headers)
let partialStatic (pageTitle : string) content : HttpHandler =
fun next ctx -> backgroundTask {
let isPartial = ctx.Request.IsHtmx && not ctx.Request.IsHtmxRefresh
let! pageCtx = pageContext ctx pageTitle content
let view = (match isPartial with true -> partial | false -> view) pageCtx
return!
(next, ctx)
||> match user ctx with
| Some u ->
match Messages.pop u with
| Some (msg, url) -> setHttpHeader "X-Toast" msg >=> withHxPush url >=> writeView view
| None -> writeView view
| None -> writeView view
}

A quick overview of this function:

  • Line 4 determines if this an htmx boosted request (a “page”-like requests)
  • Line 5 creates a rendering context for the page
  • Line 6 renders the view to a string, calling partial or view with the page rendering context
  • Lines 10-13 are only executed if a user is logged on, and line 12 is the one that appends a message and a new URL

A quick note about line 12: the >=> operator joins Giraffe HttpHandlers together. An HttpHandler takes an HttpContext and the next function to be executed, and returns a Task<HttpContext option> (an asynchronous call that may or may not return a context). If there is no context returned, the chain stops; the function can also return an altered context. It is good practice for an HttpHandler to make a single change to the context; this keeps them simple, and allows them to be plugged in however the developer desires. Thus, the setHttpHeader call adds the X-Toast header, the withHxPush call adds the HX-Push header, and the writeView call sets the response body to the rendered view.

The new URL part does not actually make the browser do anything; it simply pushes the given URL onto the browser’s history stack. Technically, the browser receives the content from the P-R-G as the response to its POST; as we’re replacing the current page, though, we need to make sure the URL stays in sync.

Of note is that not all toasts are this complex. For example, the “cancel snooze” handler return looks like this:

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return! (withSuccessMessage "Request unsnoozed" >=> Components.requestItem requestId) next ctx

…while the withSuccessMessage handler is:

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/// Add a success message header to the response
let withSuccessMessage : string -> HttpHandler =
sprintf "success|||%s" >> setHttpHeader "X-Toast"

No dictionary, no redirect, just a single response that will show a toast.

You made it - the toast section is toast! There is one more interesting interaction, though; that of the modal dialog.

Bootstrap’s implementation of modal dialogs also uses JavaScript; however, for the purposes of the modals used in myPrayerJournal v3, we can use the data- attributes to show them. Here is the view for a modal dialog that allows the user to snooze a request (hiding it from the active list until the specified date); this is rendered a single time on the journal view page:

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div [
_id "snoozeModal"
_class "modal fade"
_tabindex "-1"
_ariaLabelledBy "snoozeModalLabel"
_ariaHidden "true"
] [
div [ _class "modal-dialog modal-sm" ] [
div [ _class "modal-content" ] [
div [ _class "modal-header" ] [
h5 [ _class "modal-title"; _id "snoozeModalLabel" ] [ str "Snooze Prayer Request" ]
button [ _type "button"; _class "btn-close"; _data "bs-dismiss" "modal"; _ariaLabel "Close" ] []
]
div [ _class "modal-body"; _id "snoozeBody" ] [ ]
div [ _class "modal-footer" ] [
button [ _type "button"; _id "snoozeDismiss"; _class "btn btn-secondary"; _data "bs-dismiss" "modal" ] [
str "Close"
]
]
]
]
]

Notice that #snoozeBody is empty; we fill that when the user clicks the snooze icon:

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button [
_type "button"
_class "btn btn-secondary"
_title "Snooze Request"
_data "bs-toggle" "modal"
_data "bs-target" "#snoozeModal"
_hxGet $"/components/request/{reqId}/snooze"
_hxTarget "#snoozeBody"
_hxSwap HxSwap.InnerHtml
] [ icon "schedule" ]

This uses data-bs-toggle and data-bs-target, Bootstrap attributes, to show the modal. It also uses hx-get to load the snooze form for that particular request, with hx-target targeting the #snoozeBody div from the modal definition. Here is how that form is defined:

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/// The snooze edit form
let snooze requestId =
let today = System.DateTime.Today.ToString "yyyy-MM-dd"
form [
_hxPatch $"/request/{RequestId.toString requestId}/snooze"
_hxTarget "#journalItems"
_hxSwap HxSwap.OuterHtml
] [
div [ _class "form-floating pb-3" ] [
input [ _type "date"; _id "until"; _name "until"; _class "form-control"; _min today; _required ]
label [ _for "until" ] [ str "Until" ]
]
p [ _class "text-end mb-0" ] [ button [ _type "submit"; _class "btn btn-primary" ] [ str "Snooze" ] ]
]

Here, the form uses hx-patch to submit the data to the snooze endpoint. The target for the response, though, is #journalItems; this is the element that holds all of the prayer request cards. Snoozing a request will remove it from the active list, so the list needs to be refreshed; this will make that happen.

Look back at the modal definition; at the bottom, there is a “Close” button. We will use this to dismiss the modal once the update succeeds. In the Giraffe handler to snooze a request, here is its return statement:

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return!
(withSuccessMessage $"Request snoozed until {until.until}"
>=> hideModal "snooze"
>=> Components.journalItems) next ctx

Notice that hideModal handler?

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/// Hide a modal window when the response is sent
let hideModal (name : string) : HttpHandler =
setHttpHeader "X-Hide-Modal" name

Yes, it’s another HTTP header! One can certainly get carried away with custom HTTP headers, but their very existence is to communicate with the client (browser) outside of the visible content of the page. Here, we’re passing the name “snooze” to this header; in our htmx:afterOnLoad handler, we’ll consume this header:

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htmx.on("htmx:afterOnLoad", function (evt) {
const hdrs = evt.detail.xhr.getAllResponseHeaders()
// ...
// Hide a modal window if requested
if (hdrs.indexOf("x-hide-modal") >= 0) {
document.getElementById(evt.detail.xhr.getResponseHeader("x-hide-modal") + "Dismiss").click()
}
})

The “Close” button on our modal was given the id of snoozeDismiss; this mimics the user clicking the button, which Bootstrap’s data- attributes handle from there. Of all the design choices and implementations I did in this conversion, this part strikes me as the most “hack”y. However, I did try to hook into the Bootstrap modal itself, and hide it via script; however, it didn’t like initializing a modal a second time, and I could not get a reference to it from the htmx:afterOnLoad handler. Clicking the button works, though, even when it’s done from script.

CSS Transitions in htmx

This post has already gotten much longer than I had planned, but I wanted to make sure I covered this.

  • When htmx requests are in flight, the framework makes it easy to show indicators.
  • I mentioned swapping and settling when discussing the events htmx exposes. The way this is done, CSS transitions will render as expected. They have a host of examples to spark your imagination.

As I was keeping the UI the same, I did not end up using these options; however, their presence demonstrates that htmx is a true batteries-included SPA framework.


Up next, we’ll step away from the front end and dig into LiteDB.

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September 2, 2018
  A Tour of myPrayerJournal: Conclusion

NOTE: This is the final post of an 8-post series; see the introduction for all of them, and the requirements for which this software was built.

Over the course of this tour, we’ve meandered through client side code, server side code, a database, and documentation. However, the experience of developing an application is more than just the sum of the assembled technologies and techniques. Let’s take a look at some of these “lessons learned” and opinions formed through this process. (This post will use the first-person singular pronouns “I” / “me” / “my” a lot more than the previous ones.)

Vue Is Awesome – But…

As I tried different SPA frameworks, they were interesting and fun, but a lot more work than I expected. Then, I came across Vue, and its paradigm and flow just clicked. Single file components are great; it was so nice to not have to go digging through a site-wide CSS file looking for styles that affected the elements in the component. I just had to scroll down! While I did put the common CSS in App.vue, the application’s top component, anything unique that component did was right there. There are also all kinds of Vue-aware packages that you can add and use, that add their own elements/components to the process; Element UI, Bootstrap Vue, and Vue-Awesome were three of the ones I used at different points in development. Since it’s a JavaScript framework, you can use vanilla JS packages as well; myPrayerJournal uses moment.js to display relative dates (“last activity 8 minutes ago”) and format dates for display.

Then… I ran the build process, and the bundles were huge – as in, multiple megabytes huge! We changed our implementation of Vue-Awesome to only import the icons we used in the application (to be fair to them, that is the project’s recommendation). Element also seemed to be rather heavy. One of the last issues I worked before final release was removing Bootstrap Vue and just using straight HTML/CSS for layout and flow (which is another lesson we’ll explore below). There are guides on configuring Webpack to help make moment’s bundle smaller (and that project has an open issue to refactor so that it’s more friendly to a “just import the part you need” paradigm).

None of this is meant as a knock of any of the fine projects I’ve named up to this point. It was also near the end of the project when I converted to the Vue CLI v3 template, which uses a version of Webpack that has a much better “tree-shaking” algorithm. (This means that, if it can establish that code is never executed, it excludes it from the bundle.) myPrayerJournal v1.0’s modern “vendor” bundle (the one with the libraries) is 283K, while the legacy bundle is 307K; while that’s not lightning fast on mobile, it’s also comparable to a lot of other sites, and since page updates happen through the API, it is fast once it’s loaded.1

Lesson: Be smart about what you import.

Lesson: The JavaScript ecosystem evolves quickly. This was published September 2nd, 2018, describing development that occurred September 2016 through August 2018; a good bit of this is likely already obsolete. :)

You Might Not Need…

We mentioned above that the site eventually was written with simple HTML and CSS. Many of the more popular packages and utilities were created to make up for deficiencies, either in the browser ecosystem or among the differing browser vendors. With the recent efforts by browser vendors to support published standards, though, many of these packages are used for reasons that distill to comfort and inertia. As before, this is not a knock on these projects; they filled a definite need, and continue to work as the basis for a lot of deployed, executing code.

For new development, though, existing standards – and their support – may be sufficient. There are some great sites that detail how certain things can be done using plain JavaScript or CSS.

I used the last one quite a bit. I also extensively referred to CSS Tricks’ “A Complete Guide to Flexbox” post. When I decided to rework the layout without Bootstrap, I thought the replacement would be CSS Grid; however, Flexbox was more than enough.

Lesson: Use a framework if you want, but don’t assume it’s the only way to do things.

Lesson: If you want to shrink your bundle size, 20-30 lines of your own code can sometimes save you 20-30K (or more).

Learn Go

Ladies and gentlemen of the Internet class of 2018 -
  Learn Go.
If I could offer you only one tip for the future,
  Go would be it.
with apologies to Baz Luhrmann

Go is a systems programming language. It was developed at Google, to help them better utilize their hardware. It natively supports concurrent processing (which can be done in parallel, but is distinct from “parallel programming”); has an opinionated code formatter; forces you to address calls that may error; and is terribly efficient. When myPrayerJournal was running with the Go backend, the working size in RAM was around 10MB. Let me say that again, this time with feeling - the working size for a database-accessing, HTTP-listening, dynamic web service was 10MB of RAM! If you have ever profiled a web server process, you know that it’s nearly ludicrous how small this is. For comparison, the process working set for the F#/Giraffe/EF Core version of the backend runs between 60-80MB, and includes another ~256MB of shared working set memory.2 (An Apache2 process running PHP can run in the 256MB range as well.)

Why am I recommending a technology that I ultimately moved away from before the v1.0 release? Well, other than “did you read the last paragraph?!?!”, the short answer is “it’s the future, and will change how you code in every other language.” The fact that it forces you to deal with every single thing that may error makes it robust; but, if you learn to develop with it, you will find yourself thinking about error handling more fully than you did before – and I say this as a person who already coded error handlers as I coded the happy path.

Why did I move away from a technology on which I’m so bullish? Well, for starters, F# is the language that “clicks” for me in the same way that Vue did as a client-side framework; its development paradigm just makes sense with the way I think about structuring code. I completed a project that used F# and Giraffe (which I hope to take open-source soon), and that gave me the confidence to move forward with a third attempt at an F# API. (Third time’s the charm, right?) Also, while Entity Framework generated some pretty verbose SQL statements, EF Core more or less generates what I would have written anyway, plus it takes care of populating the objects it returns from the database.

I also found the development process awkward, though not unwieldy. (They’re probably not going to adopt that as their slogan…) Much has been written about the GOPATH environment variable, but once you get into it, it starts to make sense. go get is great at pulling down your dependencies, and the way it does it, you can peruse the source code to see exactly what they are doing. Also, it was not too difficult to develop on Windows, but build executables for Linux – which, in the “systems” programming work, is a really cool feature.

Lesson: Learn Go.

Write about Your Code

This wasn’t a lesson I learned on this project; this was one I’d known for a while. There are (at least) two distinct benefits to writing about your code:

  • It can help you learn even more than you may have learned when you were writing the code itself. As developers, we sometimes forget to step back and look at the body of work we’ve created. If you write about it, you have to form a coherent view about it so you can explain it to others; this helps you long-term. Also, people who know more about the environment can chime in on what you’ve written, which also not only helps you learn, …
  • It helps build community. If you hit a snag, and someone in the community around that technology helps you get past it, writing about your experience means that the next person to encounter that issue may not have to ask; if their searching leads them to your post, they can fix it and move on. This applies doubly if you could not get help from the community; you might be the one who surfaces this issue/technique, and moves the entire community forward.

Lesson: Write about your code; participate in the community around your technology to whatever extent you are able.

 

If you’ve been with us for this entire tour – thank you. I hope you’ve learned something; I know I have, not just through the development of myPrayerJournal, but through the course of writing about it. And, certainly, if you feel that this application could help you in any way, help yourself. It is and will always be free, and Bit Badger Solutions (and DJS Consulting before it) has, as of this writing, a 14-year streak of no known data breaches; your prayer requests are safe with us.


1 There are chunk-splitting techniques that can be used to make the initial download smaller, and load other portions on-demand. Moment.js, for example, isn’t needed for the default “Welcome to myPrayerJournal” page. We could defer loading that until the user has logged in, as the journal page definitely needs it; we’d still have to download the same amount, but it would be spread out across 2 requests. Opportunities to save some size in the initial download are still out there, but 283K is just above the 244K suggested bundle size, so we went forward with it.

2 The server on which I host myPrayerJournal already has other .NET Core processes running on it, so the shared memory size has already been allocated.

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