xref: /external/markdown/docs/reference.md

title: Library Reference

# Using Markdown as a Python Library

First and foremost, Python-Markdown is intended to be a python library module
used by various projects to convert Markdown syntax into HTML.

## The Basics

To use markdown as a module:

```python
import markdown
html = markdown.markdown(your_text_string)
```

## The Details

Python-Markdown provides two public functions ([`markdown.markdown`](#markdown)
and [`markdown.markdownFromFile`](#markdownFromFile)) both of which wrap the
public class [`markdown.Markdown`](#Markdown). If you're processing one
document at a time, these functions will serve your needs. However, if you need
to process multiple documents, it may be advantageous to create a single
instance of the `markdown.Markdown` class and pass multiple documents through
it. If you do use a single instance though, make sure to call the `reset`
method appropriately ([see below](#convert)).

### markdown.markdown(text [, **kwargs]) {: #markdown data-toc-label='markdown.markdown' }

The following options are available on the `markdown.markdown` function:

__text__{: #text }

:   The source Unicode string. (required)

    !!! note "Important"
        Python-Markdown expects a **Unicode** string as input (some simple ASCII binary strings *may* work only by
        coincidence) and returns output as a Unicode string. Do not pass binary strings to it! If your input is
        encoded, (e.g. as UTF-8), it is your responsibility to decode it.  For example:

            :::python
            with open("some_file.txt", "r", encoding="utf-8") as input_file:
                text = input_file.read()
            html = markdown.markdown(text)

        If you want to write the output to disk, you *must* encode it yourself:

            :::python
            with open("some_file.html", "w", encoding="utf-8", errors="xmlcharrefreplace") as output_file:
                output_file.write(html)

__extensions__{: #extensions }

:   A list of extensions.

    Python-Markdown provides an [API](extensions/api.md) for third parties to
    write extensions to the parser adding their own additions or changes to the
    syntax. A few commonly used extensions are shipped with the markdown
    library. See the [extension documentation](extensions/index.md) for a
    list of available extensions.

    The list of extensions may contain instances of extensions and/or strings
    of extension names.

        :::python
        extensions=[MyExtClass(), 'myext', 'path.to.my.ext:MyExtClass']

    !!! note
        The preferred method is to pass in an instance of an extension. Strings
        should only be used when it is impossible to import the Extension Class
        directly (from the command line or in a template).

    When passing in extension instances, each class instance must be a subclass
    of `markdown.extensions.Extension` and any configuration options should be
    defined when initiating the class instance rather than using the
    [`extension_configs`](#extension_configs) keyword. For example:

        :::python
        from markdown.extensions import Extension
        class MyExtClass(Extension):
            # define your extension here...

        markdown.markdown(text, extensions=[MyExtClass(option='value')])

    If an extension name is provided as a string, the string must either be the
    registered entry point of any installed extension or the importable path
    using Python's dot notation.

    See the documentation specific to an extension for the string name assigned
    to an extension as an entry point.  Simply include the defined name as
    a string in the list of extensions. For example, if an extension has the
    name `myext` assigned to it and the extension is properly installed, then
    do the following:

        :::python
        markdown.markdown(text, extensions=['myext'])

    If an extension does not have a registered entry point, Python's dot
    notation may be used instead. The extension must be installed as a
    Python module on your PYTHONPATH. Generally, a class should be specified in
    the name. The class must be at the end of the name and be separated by a
    colon from the module.

    Therefore, if you were to import the class like this:

        :::python
        from path.to.module import MyExtClass

    Then load the extension as follows:

        :::python
        markdown.markdown(text, extensions=['path.to.module:MyExtClass'])

    If only one extension is defined within a module and the module includes a
    `makeExtension` function which returns an instance of the extension, then
    the class name is not necessary. For example, in that case one could do
    `extensions=['path.to.module']`. Check the documentation for a specific
    extension to determine if it supports this feature.

    When loading an extension by name (as a string), you can only pass in
    configuration settings to the extension by using the
    [`extension_configs`](#extension_configs) keyword.

    !!! seealso "See Also"
        See the documentation of the [Extension API](extensions/api.md) for
        assistance in creating extensions.

__extension_configs__{: #extension_configs }

:   A dictionary of configuration settings for extensions.

    Any configuration settings will only be passed to extensions loaded by name
    (as a string). When loading extensions as class instances, pass the
    configuration settings directly to the class when initializing it.

    !!! Note
        The preferred method is to pass in an instance of an extension, which
        does not require use of the `extension_configs` keyword at all.
        See the [extensions](#extensions) keyword for details.

    The dictionary of configuration settings must be in the following format:

        :::python
        extension_configs = {
            'extension_name_1': {
                'option_1': 'value_1',
                'option_2': 'value_2'
            },
            'extension_name_2': {
                'option_1': 'value_1'
            }
        }

    When specifying the extension name, be sure to use the exact same
    string as is used in the [extensions](#extensions) keyword to load the
    extension. Otherwise, the configuration settings will not be applied to
    the extension. In other words, you cannot use the entry point in on
    place and Python dot notation in the other. While both may be valid for
    a given extension, they will not be recognized as being the same
    extension by Markdown.

    See the documentation specific to the extension you are using for help in
    specifying configuration settings for that extension.

__output_format__{: #output_format }:

:   Format of output.

    Supported formats are:

    * `"xhtml"`: Outputs XHTML style tags. **Default**.
    * `"html5"`: Outputs HTML style tags.

    The values can be in either lowercase or uppercase.

__tab_length__{: #tab_length }:

: Length of tabs in the source. Default: 4

### `markdown.markdownFromFile (**kwargs)` {: #markdownFromFile data-toc-label='markdown.markdownFromFile' }

With a few exceptions, `markdown.markdownFromFile` accepts the same options as
`markdown.markdown`. It does **not** accept a `text` (or Unicode) string.
Instead, it accepts the following required options:

__input__{: #input } (required)

:   The source text file.

    `input` may be set to one of three options:

    * a string which contains a path to a readable file on the file system,
    * a readable file-like object,
    * or `None` (default) which will read from `stdin`.

__output__{: #output }

:   The target which output is written to.

    `output` may be set to one of three options:

    * a string which contains a path to a writable file on the file system,
    * a writable file-like object,
    * or `None` (default) which will write to `stdout`.

__encoding__{: #encoding }

:   The encoding of the source text file.

    Defaults to `"utf-8"`. The same encoding will always be used for input and output.
    The `xmlcharrefreplace` error handler is used when encoding the output.

    !!! Note
        This is the only place that decoding and encoding of Unicode
        takes place in Python-Markdown. If this rather naive solution does not
        meet your specific needs, it is suggested that you write your own code
        to handle your encoding/decoding needs.

### markdown.Markdown([**kwargs]) {: #Markdown data-toc-label='markdown.Markdown' }

The same options are available when initializing the `markdown.Markdown` class
as on the [`markdown.markdown`](#markdown) function, except that the class does
**not** accept a source text string on initialization. Rather, the source text
string must be passed to one of two instance methods.

!!! warning

    Instances of the `markdown.Markdown` class are only thread safe within
    the thread they were created in. A single instance should not be accessed
    from multiple threads.

#### Markdown.convert(source) {: #convert data-toc-label='Markdown.convert' }

The `source` text must meet the same requirements as the [`text`](#text)
argument of the [`markdown.markdown`](#markdown) function.

You should also use this method if you want to process multiple strings
without creating a new instance of the class for each string.

```python
md = markdown.Markdown()
html1 = md.convert(text1)
html2 = md.convert(text2)
```

Depending on which options and/or extensions are being used, the parser may
need its state reset between each call to `convert`.

```python
html1 = md.convert(text1)
md.reset()
html2 = md.convert(text2)
```

To make this easier, you can also chain calls to `reset` together:

```python
html3 = md.reset().convert(text3)
```

#### Markdown.convertFile(**kwargs) {: #convertFile data-toc-label='Markdown.convertFile' }

The arguments of this method are identical to the arguments of the same
name on the `markdown.markdownFromFile` function ([`input`](#input),
[`output`](#output), and [`encoding`](#encoding)). As with the
[`convert`](#convert) method, this method should be used to
process multiple files without creating a new instance of the class for
each document. State may need to be `reset` between each call to
`convertFile` as is the case with `convert`.