Dynamic Form Fields with WTForms, Flask, HTMX, and Frustration

I've been working on creating a data layer generator using flask-wtf for quite some time -- 6 months I think -- and was quite perplexed when I wanted to create a dynamic form field where you can add/remove form fields. The idea was that you had a basic event group and event name as a required parameter and you can add more custom parameters to build your data layer. The output would be a pretty printed JSON you can copy without worrying about missing brackets, or structure.

There were two references that I thought would be great:

• Dynamic Forms with Flask by Miguel Grinberg, and

• Dynamic fields with Flask-WTF by Rafael Medina

Both were great at explaining WTF was WTForms. The documentation for the package itself got me quite lost. But it was integrated with flask so I thought it would be less of a pain and there should be a lot of references right? Well, those were the only two reference that matched what I was looking for.

Geekforgeeks had a good tutorial and was one of the indicator that using htmx wasn't a bad idea and JustDjango gave me an idea on how tohx-swap conveniently. I actually started with these articles and didn't come back for another month because I could not translate it into what I wanted.

Not Pythonic Enough

Grinberg's and Medina's solution was the best I could find but it had some issues for me: the use of macros and javascript. I really did not want to overcomplicate my code by adding too much bells and whistles, I only wanted this piece of code to work.

<button type="button" 
    hx-post="{{ url_for('add_dl_form') }}" 
    hx-target="#parameter" 
    hx-swap="beforeend"> 
    Add Parameter 
</button>

This should add a form after the required parameters (event group and event name). Simple. But both Grinberg and Medina became complicated fast because of how FieldLists work in WTForms. They needed to have an index that points the form inputs. The docs mention this but does not give an example on how to implement it.

After reading it twenty times, I noticed that FieldList had an append_entry() function. Since most references would do a for loop for the entries which would mean it would contain the list of fields and can be easily manipulated.

@app.route("/add-dl-form",methods=['POST'])
def add_dl_form():
    eventform = EventForm()
    eventform.parameters.append_entry()
    form_len = eventform.parameters.__len__()
    form = eventform.parameters.entries[form_len-1]


    return render_template("datalayer_param.html",form=form)

In combination with the hx-post method we can swap any tag with an id=parameter with whatever is in datalayer_param.html, which in this case would be:

<br>
{{form.parameter_key.label}}
{{form.parameter_key(class_="input")}}
<br>
{{form.parameter_value.label}}
{{form.parameter_value(class_="input")}}

Third Party Cookies, A Eulogy

The Age of 1P Data

First-party (1P) data has always been superior when it comes to analytics. Companies and consultancies have been gunning for in-house solutions for the last couple of decades. At the very least, clawing for some freedom from third-party (3P) dependency. The problem is developing a good and reliable analytics solution is not that simple. There is the cost of time to research and maintain. Also, there is the financial cost of the infrastructure. Analytics rely heavily on historical data which becomes less and less cheap as the data grows, a large amount of focus is needed in developing and maintaining it. As a result, companies find it way more affordable to use analytics platforms and products that also offer customizability. Full discretion, I will not be naming products or platforms -- can not offend the tech overlords, at least not in this article.

Platform Distrust

As someone who has both worked analytics client-side and as a consultant for the breadth of my career, one of the challenges of adopting an analytics platform is convincing your peers (and yourself to some extent) that the product is fine. Objectively, is it good? Well, whatever you are using it is probably good enough. If it is highly adopted across industries and a source of truth for many, why wouldn't it be? High adoption usually means a lot of eyes are monitoring bugs and hurdles when using a product, this can be something as fundamental as basic setup or as specific as data discrepancy. If it has a healthy community you can find answers in forums or support documents.

But the above is a data worker's perspective.

The 1P Data Party

Is 3P data such a bad thing that we should stay away from it? There has always been polemic around this issue, especially when it comes to privacy. There are multiple ways to interpret this, and all of them will have a negative response from every side of the issue. The 3P cookie method, was developed at a time where digital marketing was at its infancy, when the web was still young. What was considered an exploit became a celebrated feature. It was a better way to do marketing after all, datain its most convenient form at that time was being leveraged to deliver messages that the consumers (allegedly) wanted. This beats the expensive alternative of market reasearch with panel surveys. After the uprising of privacy awareness -- or reemergence, since anonimity was a core concept of the early web -- 1P data became the buzzword for digital marketing.

First Party Data Search Trend 2014-2024

Suddenly adtech had no choice but to go back to basics due to imense public and political pressure. Privacy was important again. The case for 1P data is that it is a more trustworthy data. Instead of aggregates, we get real users doing real things, and with the growth of technology, tools for measuring propensity are getting better and better. We have the capability on collecting and processing so much data -- with consent, of course. We should always have our sights on the ever expanding edge of technology.

We are consistently trying to learn and educate about analytics the "right way" (hot take: sessions are not a good measure for performance marketing) push back from marketers -- the disdain you feel about a certain "new" fascistic analytics platform -- is expected. Relearning something every other July is a pain, but that is what constantly happens when you are tech adjacent. In my area of expertise its a fact of work. We adapt, see every other tool that can help us, adopt and build solutions.

The honest question is: was 3P data with its vast amount more reliable than 1P data? Did we even miss anything? That is something to ponder internally, how did you really benefit from something that always belonged to the vendors anyway? And, how does today differ? It is just another change to the internet landscape and another day of adapting to the everchanging tech.

Herr Pidde

It was check-in time, boarding is not due for another two hours. Travelling during the pandemic will always be harrowing, all the what ifs and possible outcomes fill your head like an avalanche. It was supposed to be overweight, it was predicted disaster. “Save your money for your wife” said Herr Pidde.

As we waited to pay for the overweight charge he coincidentally was there also, reporting to the supervisor, he came up and asked if this was in fact my wife, and he introduced himself apologizing that there had to be an overweight charge, “I need to be strict or I will get in trouble” Herr Pidde said with a jolly smile. You see, he had helped me shift the weight from my overweight luggage to my carry-on bag, two kilograms worth, which made the carry-on even more heavy than allowed. “Its overweight” I said matter-of-factly referring to the carry-on bag, Herr Pidde just winked to me and said, “No, I think its fine.” He printed the baggage check for my carry-on giving it the all clear and reuttered the words, “Save your money for your wife.”

Chaos and grief is rampant at the time of writing, those of you who were there would relate. Herr Pidde is the epitome of resisting that grief, resisting for our animal urges to turn us into assholes, resisting hopelessness and fear, resisting our ever common air grasping in a position of power. That making other’s lives easier should be the default, genuine service to your fellow creature.

A smile, some tears, and a reminder for my future self in respect to Herr S. Pidde.