alexkwolfe / prmd

JSON Schema tools and doc generation for HTTP APIs

Geek Repo:Geek Repo

Github PK Tool:Github PK Tool


JSON Schema tooling: scaffold, verify, and generate documentation from JSON Schema documents.


JSON Schema provides a great way to describe an API. prmd provides tools for bootstrapping a description like this, verifying its completeness, and generating documentation from the specification.

To learn more about JSON Schema in general, start with this excellent guide and supplement with the specification. The JSON Schema usage conventions expected by prmd specifically are described in /docs/


Install the command-line tool with:

$ gem install prmd

If you're using prmd within a Ruby project, you may want to add it to the application's Gemfile:

gem 'prmd'
$ bundle install


Prmd provides four main commands:

  • init: Scaffold resource schemata
  • combine: Combine schemata and metadata into single schema
  • verify: Verify a schema
  • doc: Generate documentation from a schema
  • render: Render views from schema

Here's an example of using these commands in a typical workflow:

# Fill out the resource schemata
$ mkdir -p schemata
$ prmd init app  > schemata/app.json
$ prmd init user > schemata/user.json
$ vim schemata/{app,user}.json   # edit scaffolded files

# Provide top-level metadata
$ cat <<EOF > meta.json
 "description": "Hello world prmd API",
 "id": "hello-prmd",
 "links": [{
   "href": "",
   "rel": "self"
 "title": "Hello Prmd"

# Combine into a single schema
$ prmd combine --meta meta.json schemata/ > schema.json

# Check it’s all good
$ prmd verify schema.json

# Build docs
$ prmd doc schema.json >

Render from schema

$ prmd render --template schemata.erb schema.json >

Typically you'll want to prepend header and overview information to your API documentation. You can do this with the --prepend flag:

$ prmd doc schema.json --prepend >

You can also chain commands together as needed, e.g.:

$ prmd combine --meta meta.json schemata/ | prmd verify | prmd doc --prepend >

See prmd <command> --help for additional usage details.

File Layout

We suggest the following file layout for JSON schema related files:

/docs (top-level directory for project documentation)
  /schema (API schema documentation)
      /{resource.json} (individual resource schema)
    /meta.json (overall API metadata)
    / (preamble for generated API docs)
    /schema.json (complete generated JSON schema file)
    / (complete generated API documentation file)


  1. Fork it
  2. Create your feature branch (git checkout -b my-new-feature)
  3. Commit your changes (git commit -am 'Add some feature')
  4. Push to the branch (git push origin my-new-feature)
  5. Create new Pull Request


JSON Schema tools and doc generation for HTTP APIs

License:MIT License