Auto_Description.Py

A Markata plugin to create automatic descriptions for markdown documents. It does this by grabbing the first {len} number of characters from the document that are in a paragraph.

Configuration

Open up your markata.toml file and add new entries for your auto_descriptions. You can have multiple desriptions, each one will be named after the key you give it in your config.

        
[markata]

# make sure its in your list of hooks
hooks=[
   "markata.plugins.auto_description",
   ]

[markata.auto_description.description]
len=160
[markata.auto_description.long_description]
len=250
[markata.auto_description.super_description]
len=500

Make sure that you have the auto_description plugin in your configured hooks.

In the above we will end up with three different descritpions, (description, long_description, and super_description) each will be the first number of characters from the document as specified in the config.

Defaults

By default markata will set description to 160 and long_description to 250, if they are not set in your config.

Using the Description

Downstream hooks can now use the description for things such as seo, or feeds. Here is a simple example that lists all of the descriptions in all posts. This is a handy thing you can do right from a repl.

        
from markata import Markata
m = Markata()
[p["description"] for p in m.articles]

!! function

get_description function

        
        def get_description(article: "Post") -> str:
            """
            Get the full-length description for a single post using the commonmark
            parser.  Only paragraph nodes will count as text towards the description.
            """
            ast = _parser.parse(article.content)

            # find all paragraph nodes
            paragraph_nodes = [
                n[0]
                for n in ast.walker()
                if n[0].t == "paragraph" and n[0].first_child.literal is not None
            ]
            # for reasons unknown to me commonmark duplicates nodes, dedupe based on sourcepos
            sourcepos = [p.sourcepos for p in paragraph_nodes]
            # find first occurence of node based on source position
            unique_mask = [sourcepos.index(s) == i for i, s in enumerate(sourcepos)]
            # deduplicate paragraph_nodes based on unique source position
            unique_paragraph_nodes = list(compress(paragraph_nodes, unique_mask))
            paragraphs = " ".join([p.first_child.literal for p in unique_paragraph_nodes])
            paragraphs = html.escape(paragraphs)
            return paragraphs

!! function

set_description function

        
        def set_description(
            markata: "Markata",
            article: "Post",
            cache: "FanoutCache",
            config: Dict,
            max_description: int = 500,
            plugin_text: None = "",
        ) -> None:
            """
            For a given `article`, find the description, put it in the cache, and set
            the configured descriptions for the article.
            """
            key = markata.make_hash(
                article.content,
                plugin_text,
                config,
            )

            description_from_cache = markata.precache.get(key)
            if description_from_cache is None:
                description = get_description(article)[:max_description]
                markata.cache.add(key, description, expire=markata.config.default_cache_expire)
            else:
                description = description_from_cache

            for description_key in config:
                if description_key not in ["cache_expire", "config_key"]:
                    # overwrites missing (None) and empty ('')
                    if not article.metadata.get(description_key):
                        article.metadata[description_key] = description[
                            : config[description_key]["len"]
                        ]

!! function

pre_render function

        
        def pre_render(markata: "Markata") -> None:
            """
            The Markata hook that will set descriptions for all posts in the pre-render phase.
            """
            config = markata.get_plugin_config(__file__)

            if "description" not in config.keys():
                config["description"] = {}
                config["description"]["len"] = 160

            if "long_description" not in config.keys():
                config["long_description"] = {}
                config["long_description"]["len"] = 250

            def try_config_get(key: str) -> Any:
                try:
                    return config.get(key).get("len") or None
                except AttributeError:
                    return None

            max_description = max(
                [
                    value
                    for description_key in config
                    if (value := try_config_get(description_key))
                ],
            )

            with markata.cache as cache:
                for article in markata.iter_articles("setting auto description"):
                    set_description(
                        markata=markata,
                        article=article,
                        cache=cache,
                        config=config,
                        max_description=max_description,
                        plugin_text=Path(__file__).read_text(),
                    )

!! function

try_config_get function

        
        def try_config_get(key: str) -> Any:
                try:
                    return config.get(key).get("len") or None
                except AttributeError:
                    return None