Lektor Polymorphic Type

This plugin adds a new polymorphic lektor field type, polymorphic. The determination of the actual type implementation of the field value is deferred until evaluation time.

A motivating use case is to support having a “body” field whose formatting can be switched between, e.g., markdown, and html (or some other formatted type, such as reStructuredText.)

Installation

Add lektor-polymorphic-type to your project from command line:

lektor plugins add lektor-polymorphic-type

See the Lektor plugin documentation for more information.

How It Works

If the field has a polymorphic_type option set, that value is evaluated and the result is interpreted as the name of the final type for the field.

If no polymorphic_type option is set for the field, then we look for a field on the current record whose name is name of the current field with “_type” appended.

Examples

Simple Example

Here is an example model file for a simple page, with a selectable body format:

# page.ini

[model]
name = Page
label = {{ this.title }}

[fields.title]
label = Title
type = string

[fields.body]
label = Body
type = polymorphic

[fields.body_type]
label = Body Type
type = select
choices = markdown, html, text
default = markdown

Here, the value of the body_type field on a particular page will determine whether the body field is interpreted as being markdown, html or text.

Contrived Example

Here is a contrived example showing the use of the polymorphic_type option:

# page.ini

[model]
name = Page
label = {{ this.title }}

[fields.title]
label = Title
type = string

[fields.body]
label = Body
type = polymorphic
polymorphic_type = 'html' if this.body.lstrip().startswith('<') else 'markdown'

In this case, the body field will be interpreted as raw HTML if the content of that field starts with a “<”, otherwise it will be interpreted as Markdown text.

Author

Jeff Dairiki dairiki@dairiki.org

Changelog

0.1 — 2021-02-05

No code changes.

Update development status classifier to "stable".

Test under python 3.9. Stop testing under 3.5.

0.1b1 — 2020-05-04

Initial release.