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by rads 750 days ago
This is a good starting point if you want to get a web app going quickly: https://biffweb.com

It uses XTDB by default but you can switch to Postgres: https://biffweb.com/p/how-to-use-postgres-with-biff/

People don't really use ORMs in Clojure, they just write SQL directly and abstract the details from consumers using functions. That said, HoneySQL is a common alternative to writing SQL that makes it a lot less painful (and composable!): https://github.com/seancorfield/honeysql

2 comments

HoneySQL is so, so good. It does for SQL what Hiccup did for HTML. Once you start writing with those, it's hard to remember there's any other way.
Totally agree! or datalog is even better if you can accept not using the mainstream databases.
Biff looks neat, thanks! I mainly just don't want to write raw sql/mappers to structures for simple queries. Looks like most sql libraries with clojure can just return maps so that's neat.
Here's a quick example of how DB access generally looks in production:

    (ns rads.sql-example
      (:require [next.jdbc :as jdbc]
                [honey.sql :as sql]
                [clojure.string :as str]))

    ;; DB Table: posts
    ;; +----+-------+
    ;; | id | title |
    ;; +----+-------+
    ;; |  1 | hello |
    ;; +----+-------+

    (def ds (jdbc/get-datasource (System/getenv "DATABASE_URL")))

    (defn row->post [row]
      ;; This is your optional mapping layer (a plain function that takes a map).
      ;; You can hide DB details here.
      (update row :title str/capitalize))

    (defn get-posts [ds]
      ;; Write a SQL query using Clojure data structures.
      (let [query {:select [:*] :from [:posts]}]
        ;; Run the query.
        (->> (jdbc/execute! ds (sql/format query))
             ;; Convert each raw DB map to a "post" map
             (map row->post))))

    (println (get-posts ds))
    ;; => [{:id 1, :title "Hello"}]
You would abstract away the jdbc/execute part though, right? otherwise that's terribly unproductive compared to django etc.
In practice I do wrap `jdbc/execute!` with my own `execute!` function to set some default options. However, there is no ORM layer. What makes you think the code above is terribly unproductive?

Edit: Not trying to dismiss your concerns, by the way. In Clojure you can often get away with doing less than you might think so I'm genuinely curious about the critique.

In Django I would just do Posts.objects.filter(title=x)

I don't need to define driver boilerplate for every query (or ever have to write it... at all).

In Clojure you'll have to write the queries yourself unfortunately. People always ask, where is the fully fledged web framework in Clojure? There isn't one. Why there isn't one is hard to answer, but it's partially because the people who could write one, don't find they need one themselves.

There's definitely a preference in Clojure for not relying on frameworks, because the current people in the community like to be in control, know what's going on, or do it their own way.

That said, the whole code still ends up being relatively small. So, you kind of end up with a similar amount of total code, but you're much more in control. And if certain things you find too repetitive, you can remove the repetition yourself through many of Clojure's facilities, specifically where they annoyed you.

See: https://github.com/didibus/simple-website-with-posts where I implemented the small website you were talking about, creating posts and seeing them. The whole code is here (minus the CSS): https://github.com/didibus/simple-website-with-posts/blob/ma...

It's 95 loc and that includes the templates. There's no framework.

The key thing is experienced Clojure programmers often see a lack of ORM as a feature rather than an oversight. There were some more ORM-like libraries years ago (see Korma) but my impression is that people ultimately didn't want this and moved on to lower-level JDBC wrappers combined with HoneySQL. I found a more detailed discussion on Reddit about Clojure and ORMs back in 2020 if you want to get more info: https://reddit.com/r/Clojure/comments/g7qyoy/why_does_orm_ha...

Note that I'm not making a value judgement about Python/Django or any other library/framework combination. It's obviously a valid path, but Clojure is a different path. I can assure you there are straightforward solutions to create readable APIs like the Django example with minimal boilerplate, but the approach is fundamentally different from Python/Django.

If you do decide to build something in Clojure and think, "I already know how to do this in Django, why is it missing?", don't hesitate to join the Clojurians Slack and hop into the #beginners channel. There are plenty of people who can help you there.

There's no object in Clojure, so there's no need for an Object Relational Mapper. You just work directly of the query result sets, which the SQL library itself can conveniently turn into rows of maps if you prefer (over rows of lists).
No object is kinda mind blowing since it has java interop. I guess everything just becomes maps?
Well, there are objects through interop, and under the hood everything is compiled into one. But when you develop an app, you won't be defining classes and instantiating objects of them, you'll be instead writing functions that return maps or other data-structures.