NimblePublisher
is a minimal filesystem-based publishing engine with Markdown support and
code highlighting.
use NimblePublisher,
build: Article,
from: Application.app_dir(:app_name, "priv/articles/**/*.md"),
as: :articles,
highlighters: [:makeup_elixir, :makeup_erlang]
The example above will get all articles in the given directory,
call Article.build/3
for each article, passing the filename,
the metadata, and the article body, and define a module attribute
named @articles
with all built articles returned by the
Article.build/3
function.
Each article in the articles directory must have the format:
%{
title: "Hello world"
}
---
Body of the "Hello world" article.
This is a *markdown* document with support for code highlighters:
```elixir
IO.puts "hello world"
```
-
:build
- the name of the module that will build each entry -
:from
- a wildcard pattern where to find all entries. Files with the.md
or.markdown
extension will be converted to Markdown withEarmark
. Other files will be kept as is. -
:as
- the name of the module attribute to store all built entries -
:highlighters
- which code highlighters to use.NimblePublisher
usesMakeup
for syntax highlighting and you will need to add its.css
classes. You can generate the CSS classes by callingMakeup.stylesheet(:vim_style, "makeup")
insideiex -S mix
. You can replace:vim_style
by any style of your choice defined here. -
:earmark_options
- an%Earmark.Options{}
struct -
:parser
- custom module with aparse/2
function that receives the file path and content as params. See Custom parser for more details. -
:html_converter
- custom module with aconvert/4
function that receives the extension, body, and attributes of the markdown file, as well as all options as params. See Custom HTML converter for more details.
Let's see a complete example. First add nimble_publisher
with
the desired highlighters as a dependency:
def deps do
[
{:nimble_publisher, "~> 1.0"},
{:makeup_elixir, ">= 0.0.0"},
{:makeup_erlang, ">= 0.0.0"}
]
end
In this example, we are building a blog. Each post stays in the "posts" directory with the format:
/posts/YEAR/MONTH-DAY-ID.md
A typical blog post will look like this:
# /posts/2020/04-17-hello-world.md
%{
title: "Hello world!",
author: "Josรฉ Valim",
tags: ~w(hello),
description: "Let's learn how to say hello world"
}
---
This is the post.
Therefore, we will define a Post struct that expects all of the fields
above. We will also have a :date
field that we will build from the
filename. Overall, it will look like this:
defmodule MyApp.Blog.Post do
@enforce_keys [:id, :author, :title, :body, :description, :tags, :date]
defstruct [:id, :author, :title, :body, :description, :tags, :date]
def build(filename, attrs, body) do
[year, month_day_id] = filename |> Path.rootname() |> Path.split() |> Enum.take(-2)
[month, day, id] = String.split(month_day_id, "-", parts: 3)
date = Date.from_iso8601!("#{year}-#{month}-#{day}")
struct!(__MODULE__, [id: id, date: date, body: body] ++ Map.to_list(attrs))
end
end
Now, we are ready to define our MyApp.Blog
with NimblePublisher
:
defmodule MyApp.Blog do
alias MyApp.Blog.Post
use NimblePublisher,
build: Post,
from: Application.app_dir(:my_app, "priv/posts/**/*.md"),
as: :posts,
highlighters: [:makeup_elixir, :makeup_erlang]
# The @posts variable is first defined by NimblePublisher.
# Let's further modify it by sorting all posts by descending date.
@posts Enum.sort_by(@posts, & &1.date, {:desc, Date})
# Let's also get all tags
@tags @posts |> Enum.flat_map(& &1.tags) |> Enum.uniq() |> Enum.sort()
# And finally export them
def all_posts, do: @posts
def all_tags, do: @tags
end
Important: Avoid injecting the @posts
attribute into multiple functions,
as each call will make a complete copy of all posts. For example, if you want
to define recent_posts()
as well as all_posts()
, DO NOT do this:
def all_posts, do: @posts
def recent_posts, do: Enum.take(@posts, 3)
Instead do this:
def all_posts, do: @posts
def recent_posts, do: Enum.take(all_posts(), 3)
You may want to define other helpers to traverse your published resources. For example, if you want to get posts by ID or with a given tag, you can define additional functions as shown below:
defmodule NotFoundError do
defexception [:message, plug_status: 404]
end
def get_post_by_id!(id) do
Enum.find(all_posts(), &(&1.id == id)) ||
raise NotFoundError, "post with id=#{id} not found"
end
def get_posts_by_tag!(tag) do
case Enum.filter(all_posts(), &(tag in &1.tags)) do
[] -> raise NotFoundError, "posts with tag=#{tag} not found"
posts -> posts
end
end
You may want to define a custom function to parse the content of your files.
use NimblePublisher,
...
parser: Parser,
defmodule Parser do
def parse(path, contents) do
[attrs, body] = :binary.split(contents, ["\n---\n"])
{Jason.decode!(attrs), body}
end
end
The parse/2
function from this module receives the file path and content as params.
It must return:
- a 2 element tuple with attributes and body -
{attrs, body}
- a list of 2 element tuple with attributes and body -
[{attrs, body} | _]
You can also define a custom HTML converter that will be used to convert the file body (typically Markdown) into HTML. For example, you may wish to use an alternative Markdown parser such as md. If you want to use the built-in highlighting, you need to call it manually.
use NimblePublisher,
...
html_converter: MarkdownConverter,
highlighters: [:makeup_elixir]
defmodule MarkdownConverter do
def convert(filepath, body, _attrs, opts) do
if Path.extname(filepath) in [".md", ".markdown"] do
highlighters = Keyword.get(opts, :highlighters, [])
body |> Md.generate() |> NimblePublisher.highlight(highlighters)
end
end
end
The convert/4
function from this module receives an extension name, a body,
the parsed attributes from the file, and the options passed to
NimblePublisher
. It must return the converted body as a string.
If you are using Phoenix, you can enable live reloading by simply telling Phoenix to watch the โpostsโ directory. Open up "config/dev.exs", search for live_reload:
and add this to the list of patterns:
live_reload: [
patterns: [
...,
~r"posts/*/.*(md)$"
]
]
- Dashbit's blog post which was the foundation for NimblePublisher
- Elixir School's lesson on using NimblePublisher, complete with Phoenix integration
All nimble libraries by Dashbit:
- NimbleCSV - simple and fast CSV parsing
- NimbleOptions - tiny library for validating and documenting high-level options
- NimbleParsec - simple and fast parser combinators
- NimblePool - tiny resource-pool implementation
- NimblePublisher - a minimal filesystem-based publishing engine with Markdown support and code highlighting
- NimbleTOTP - tiny library for generating time-based one time passwords (TOTP)
Copyright 2020 Dashbit
Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except in compliance with the License. You may obtain a copy of the License at
http://www.apache.org/licenses/LICENSE-2.0
Unless required by applicable law or agreed to in writing, software distributed under the License is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the License for the specific language governing permissions and limitations under the License.