plmustache

A PostgreSQL extension that provides a language handler for Mustache templates using https://gitlab.com/jobol/mustach.

Roadmap

• variable interpolation
• sections
  • bools
  • arrays
• partials
• inheritance
• lambdas

Features

Variables

Variables are handled as per the mustache spec, a {{key}} variable will be interpolated.

create or replace function win_money(you text, qt money, at timestamptz) returns text as $$
Hello {{you}}!
You just won {{qt}} at {{at}}.
$$ language plmustache;

select win_money('Sir Meowalot', '12000', now());
                         win_money
-----------------------------------------------------------
 Hello Sir Meowalot!                                            +
 You just won $12,000.00 at 2023-12-04 07:44:26.915735-05.
(1 row)

Escaped and Unescaped

A double mustache {{key}} will be escaped and a triple mustache {{{key}}} will not be escaped.

create or replace function escape_me(tag text) returns text as $$
{{tag}}
$$ language plmustache;

select escape_me('<script>evil()</script>');
              escape_me
-------------------------------------
 &lt;script&gt;evil()&lt;/script&gt;
(1 row)

create or replace function do_not_escape_me(tag text) returns text as $$
{{{tag}}}
$$ language plmustache;

select do_not_escape_me('<script>evil()</script>');
    do_not_escape_me
-------------------------
 <script>evil()</script>
(1 row)

Sections

Boolean sections:

create or replace function show_cat(cat text, show bool default true) returns text as $$
{{#show}}
A cat appears, it's {{cat}}.
{{/show}}
{{^show}}
A mysterious cat is hiding.
{{/show}}
$$ language plmustache;

select show_cat('Mr. Sleepy');
            show_cat
---------------------------------
 A cat appears, it's Mr. Sleepy.+

(1 row)

select show_cat('Mr. Sleepy', false);
          show_cat
-----------------------------
 A mysterious cat is hiding.+

(1 row)

Array iterators:

create or replace function hello_cats(cats text[]) returns text as $$
Say hello to: {{#cats}}{{.}}, {{/cats}}
$$ language plmustache;


postgres=# select hello_cats('{Sir Meowalot, Mr. Sleepy, Paquito}');
                    hello_cats
---------------------------------------------------
 Say hello to: Sir Meowalot, Mr. Sleepy, Paquito,
(1 row)

Installation

Clone the repo and submodules:

git clone --recurse-submodules https://github.com/PostgREST/plmustache

Build mustach:

cd mustach
make && sudo make install
sudo ldconfig

Build plmustache:

cd ..

make && sudo make install

Then on SQL you can do:

CREATE EXTENSION plmustache;

plmustache is tested on Postgres 12, 13, 14, 15, 16.

Development

For testing on your local database:

make installcheck

For an isolated and reproducible enviroment you can use Nix.

$ nix-shell

$ with-pg-15 psql

$ with-pg-15 make installcheck