Usage

As tumblelogs are comprised of a stream of posts, each with a unique strucutre and schema, it is impractical for a single model to represent all types of posts. tumblelog allows you to develop separate models for each post type while maintaining the ability to query all posts at a time, regardless of the post type.

BasePostType

Post types are subclasses of tumblelog.models.BasePostType, which is itself a subclass of Django’s db.models.Model. Let’s look at an example post type for recipes, which might be defined in the models module of an app called recipes:

from django.db import models
from django.utils.translation import ugettext as _

from tumblelog.models import BasePostType

class Recipe(BasePostType):
    """
    Post type for a recipe.
    """
    intro = models.TextField(_('Introduction'))
    prep_time = models.CharField(_('Preparation Time'), max_length=128)
    cook_time = models.CharField(_('Cooking Time'), max_length=128)
    recipe_yield = models.CharField(_('Yield'), max_length=128)
    ingredients = models.TextField(_('Ingredients'))
    directions = models.TextField(_('Directions'))

    class TumblelogMeta:
        prepopulated_fields = {
            'slug': ('title',)
        }

In addition to fields, you may add model methods, custom managers, or a Meta inner class. Anything you can do with regular Django models is fair game.

You should not create a ModelAdmin for post type classes. Instead, you can define ModelAdmin properties on inner class TumblelogMeta (as is done for prepopulated_fields in the example). These are, in turn, used to dynamically generate a ModelAdmin.

Fields

BasePostType provides subclasses with each of these fields:

• slug - used to construct the URL
• title - self-explanatory
• status - defines whether a post is draft or published
• date_added - automatically created when a post is first added
• date_modified - automatically updated when a post is saved
• date_published - defines the date and time when a post is published

Properties

These properties are available to each BasePostType subclass:

• is_draft - boolean, indicates if a post is marked as draft
• is_published - boolean, indicates if a post is marked as published
• is_past - boolean, indicates if a post’s publication_date is in the past
• is_queued - boolean, indicates if a post’s publication_date is in the future (i.e. a scheduled post)
• is_public - boolean, indicates whether a post is publicly visible (i.e. both is_past and is_published are True)
• post - Post object, a GenericRelation reference to the object’s associated Post object.

Post

When an instance of a post type is first saved, a corresponding Post object is created. Post objects contain a generic foreign key to an instance of a post type, allowing you to query all post types at once.

>>> from tumblelog.models import Post
>>> Post.objects.public()
[<Post: Deboning Pony Legs (Text)>, <Post: Crostini with Pony Tartare (Recipe)>, <Post: Pony Au Poivre (Recipe)>, <Post: Pony Stew with Dried Plums (Recipe)>]

Note that the query returned instances of both Text and Recipe post types.

Fields

Each time a post type object is saved, the values of the slug, status, date_published, date_added, and date_modified fields are copied from the object to its associated Post object, allowing field lookups of each of these fields:

• slug - used to construct the URL
• status - defines whether a post is draft or published
• date_added - automatically created when a post is first added
• date_modified - automatically updated when a post is saved
• date_published - defines the date and time when a post is published

Properties

• is_draft - boolean, indicates if a post is marked as draft
• is_published - boolean, indicates if a post is marked as published
• is_past - boolean, indicates if a post’s publication_date is in the past
• is_queued - boolean, indicates if a post’s publication_date is in the future (i.e. a scheduled post)
• is_public - boolean, indicates whether a post is publicly visible (i.e. both is_past and is_published are True)
• fields - instance of a BasePostType subclass, a GenericForeignKey

Manager

Post‘s default manager is extended to include the following methods:

• status(status_code) - Convenience method for filtering objects by the status field specified in the parameter (a string; either ‘d’ or ‘p’)
• draft() - Returns posts marked as draft
• published() - Returns posts marked as published
• queued() - Returns queued posts (i.e. publish date is in the future)
• past() - Returns past posts (i.e. publish date is in the past)
• private() - Returns private posts (i.e. either future or draft)”
• public() - Returns public posts (i.e. those both past and published)