There comes a point in time during the development of a piece of software when
a configuration language needs to be used, you can only do so much via flags
before it becomes too tenuous. The language chosen should provide a format that
is easy for a person parse as well as a computer. Typically, most people would
reach for YAML, TOML, or sometimes even
JSON.
For the development of Djinn CI, none of these
fitted my needs, so I developed my own, specifically for Go.
Programming languages are always something that have fascinated me, how they're
designed, how they're implemented, and how they're used. Whether they're a DSL
(domain specific language) or more of a generic programming language. A
programming language is always something I had wanted to take a stab at
creating, even if it ended up being terrible, or being of no true utility, but
only for the sake of learning. Well, over the Christmas break I decided to
occupy my time on developing a language, one that was small and simple, designed
for a specific use case that I had encountered but hadn't found a solution for.
The language that I ended up developing was [req][req], a language designed
only for HTTP scripting.
Over these series of posts I have been exploring an approach that could be taken
when working with SQL relationships in Go. The precursor to all of this was the
initial ORMs and Query Building in Go. This explored one aspect of ORMs, the query building, but it didn't address
how relationships could also be handled in an idiomatic way. So before I wrap up
this series in this final post, let us address the code we have currently.
Previously, we
implemented some new interfaces, and utility functions to aid in the loading and
binding of the model relations. This was a much better improvement than what we
had before, however we still don't have a way of defining the relations
themselves in code. So far, we have heavily utilised callback functions to do
most of the lifting for us. For example, the model.Bind function we
implemented returns a callback that will gracefully handle binding the models we
load. In this post we will look at how we can utilise callbacks to set the
relations between models via code.
Last time, we refactored
our code, and implemented the loading of the relationships for the Post entity.
The implementation of this however was rather messy, as we did the equivalent
of sweeping everything under the rug. In this post however we will look at what
we've done, and see how this could be improved upon.
In the previous post
we setup the entity models for the blogging application, and built some custom
query options to handle the data we would be receiving via an HTTP request. Here
we will go about implementing pagination for our models, so we can support the
page query parameter, look into how we can refactor what we have in our
HTTP handlers, and start looking into loading entity relationships for models.
In my last post I
touched on the idea of using query builders for building up somewhat complex
SQL queries in Go. Well, in this post I'd like to go further, and explore how
this can be used to idiomatically build out a simple system for modelling
relationships in Go. This post going forward will assume that you have read the
aforementioned post.
Recently, I have been looking into various solutions for interacting with
databases with ease in Go. My go to library for database work in Go is
sqlx, this makes unmarshalling the data from
the database into structs a cinch. You write out your SQL query, tag your
structs using the db tag, and let sqlx
handle the rest. However, the main problem I have encountered, was with
idiomatic query building. This led me to investigate this problem, and jot down
some of my thoughts in this post.
I am an impatient man (if my sporadic typos, and last minute edits late at night
on my blog didn't make it obvious already). Recently this has started to stick
out to me much more, especially in regards to programming. More often than not I
would find myself just writing code haphazardly, then let the
compiler/interpreter point out the errors for me, some not so obvious, others
more obvious than I would have liked. This is a rather reckless approach to
take when it comes to development. I find that it prevents me from actually
thinking about what I am doing, and results in me producing tools and code that
are in unsatisfactory state.
As mentioned in my previous post, I have been working
on a tool for handling SQL migrations. Well, that tool is now ready to debug,
and is called mgrt. Much like
jrnl, I decided to take the Welsh
approach when it came to naming it.
jrnl is a simple static site generator
written in Go. It takes posts written in Markdown, and converts them to HTML.
The generated HTML files are then copied to a remote destination, this can
either be a location on disk, or to a remote server. Unlike most other static
site generators jrnl does not serve the content that is generated. This post
shall serve as a brief introduction to jrnl, for more in depth usage refer to
the readme on the project's GitHub.