Yaml

Introduction

The Yaml Extension includes the YamlOutputHandler to render output in pure Yaml, as well as the YamlConfigHandler that allows applications to use Yaml configuration files as a drop-in replacement of the default ConfigParserConfigHandler.

Documentation References:

• Configuration Settings

• Output Rendering

API References:

• Cement Yaml Extension

• Yaml Library

Requirements

• pyYaml

Cement 3.0.8+:

pip install cement[yaml]

Applications using Cement <3.0.8 should continue to include pyYaml in their dependencies.

Configuration

This extension does not support any application level configuration settings or meta options.

Usage

Config Handler

Example: Using Yaml Config Handler

myapp.py

from cement import App

class MyApp(App):
    class Meta:
        label = 'myapp'
        extensions = ['yaml']
        config_handler = 'yaml'
        config_file_suffix = '.yml'

~/.myapp.yml

---
myapp:
    foo: bar

Output Handler

In general, you likely would not set output_handler to yaml, but rather another type of output handler that displays readable output to the end-user (ex: Mustache, Jinja2, or Tabulate). However, Cement supports overriding handlers via command line options if the Handler.Meta.overridable option is set. For example, -o yaml will trigger the framework to use the yaml output handler, overriding the default set in App.Meta.output_handler.

See the documentation on Overriding Handlers via Command Line.

Example: Using Yaml Output Handler

myapp.py

from cement import App, init_defaults

META = init_defaults('output.yaml')
META['output.yaml']['overridable'] = True

class MyApp(App):
    class Meta:
        label = 'myapp'
        extensions = ['yaml', 'mustache']
        meta_defaults = META
        output_handler = 'mustache'
        template_dir = './templates'

with MyApp() as app:
    app.run()
    data = {'foo': 'bar'}
    app.render(data, 'example.m')

templates/example.m

Foo: {{ foo }}

cli

$ python myapp.py
Foo: bar

$ python myapp.py -o yaml
{foo: bar}