Creating Custom Templates for nbconvert

Selecting a template

Most exporters in nbconvert are subclasses of TemplateExporter, and make use of jinja to render notebooks into the destination format.

Alternative nbconvert templates can be selected by name from the command line with the --template option. For example, to use the reveal template with the HTML exporter, one can type.

jupyter nbconvert <path-to-notebook> --to html --template reveal

Where are nbconvert templates installed?

Nbconvert templates are directories containing resources for nbconvert template exporters such as jinja templates and associated assets. They are installed in the data directory of nbconvert, namely <installation prefix>/share/jupyter/nbconvert. Nbconvert includes several templates already.

For example, three HTML templates are provided in nbconvert core for the HTML exporter:

  • lab (The default HTML template, which produces the same DOM structure as JupyterLab)

  • classic (The HTML template styled after the classic notebook)

  • reveal (For producing slideshows).

Note

Running jupyter --paths will show all Jupyter directories and search paths.

For example, on Linux, jupyter --paths returns:

$ jupyter --paths
config:
    /home/<username>/.jupyter
    /<sys-prefix>/etc/jupyter
    /usr/local/etc/jupyter
    /etc/jupyter
data:
    /home/<username>/.local/share/jupyter
    /<sys-prefix>/share/jupyter
    /usr/local/share/jupyter
    /usr/share/jupyter
runtime:
    /home/<username>/.local/share/jupyter/runtime

Adding Additional Template Paths

In order to add additional paths to be searched, you need to pass TemplateExporter.extra_template_basedirs config options indicating the extra directories to search for templates. Be careful not to override TemplateExporter.template_paths unless you intend to replace ALL paths and don’t want the default locations included.

When using the commandline the extra template paths are added by calling --TemplateExporter.extra_template_basedirs=path/you/want/included.

The content of nbconvert templates

conf.json

Nbconvert templates all include a conf.json file at the root of the directory, which is used to indicate

  • the base template that it is inheriting from.

  • the mimetypes of the template.

  • preprocessors classes to register in the exporter when using that template.

Inspecting the configuration of the reveal template we see that it inherits from the lab template, exports text/html, and enables two preprocessors called “100-pygments” and “500-reveal”.

{
  "base_template": "lab",
  "mimetypes": {
    "text/html": true
  },
  "preprocessors": {
    "100-pygments": {
        "type": "nbconvert.preprocessors.CSSHTMLHeaderPreprocessor",
        "enabled": true
    },
    "500-reveal": {
      "type": "nbconvert.exporters.slides._RevealMetadataPreprocessor",
      "enabled": true
    }
  }
}

Inheritance

Nbconvert walks up the inheritance structure determined by conf.json and produces an agregated configuration, merging the dictionaries of registered preprocessors. The lexical ordering of the preprocessors by name determines the order in which they will be run.

Besides the conf.json file, nbconvert templates most typically include jinja templates files, although any other resource from the base template can be overriden in the derived template.

For example, inspecting the content of the classic template located in share/jupyter/nbconvert/templates/classic, we find the following content:

share/jupyter/nbconvert/templates/classic
├── static
│   └── styles.css
├── conf.json
├── index.html.j2
└── base.html.j2

The classic template exporter includes a index.html.j2 jinja template (which is the main entry point for HTML exporters) as well as CSS and a base template file in base.html.j2.

Note

A template inheriting from classic would specify "base_template": "classic" and could override any of these files. For example, one could make a “classiker” template merely providing an alternative styles.css file.

Inheritance in Jinja

In nbconvert, jinja templates can inherrit from any other jinja template available in its current directory or base template directory by name. Jinja templates of other directories can be addressed by their relative path from the Jupyter data directory.

For example, in the reveal template, index.html.j2 extends base.html.j2 which is in the same directory, and base.html.j2 extends lab/base.html.j2. This approach allows using content that is available in other templates or may be overriden in the current template.

A practical example

Say you would like to modify the existing Markdown template to wrap each output statement in a fenced code block:

```output
(1, 2, 3)
```

Start by creating a new template directory, say mdoutput. In it, you have the following files:

conf.json
index.md.j2

The configuration file, conf.json states that your template applies to markdown files:

{
  "mimetypes": {
    "text/markdown": true
  }
}

The index.md.j2 template entrypoint extends the existing markdown template, and redefines how output blocks are rendered:

{% extends 'markdown/index.md.j2' %}

{%- block traceback_line -%}
```output
{{ line.rstrip() | strip_ansi }}
```
{%- endblock traceback_line -%}

{%- block stream -%}
```output
{{ output.text.rstrip() }}
```
{%- endblock stream -%}

{%- block data_text scoped -%}
```output
{{ output.data['text/plain'].rstrip() }}
```
{%- endblock data_text -%}

You can now convert your notebook to markdown using the new template:

jupyter nbconvert --execute notebook.ipynb --to markdown --template=mdoutput

(If you put your template folder in a different location than your notebook, remember to add --TemplateExporter.extra_template_basedirs=path/to/template/parent.)

To further explore the possibilities of templating, take a look at the root of all templates: null.j2. You can find it in the ./nbconvert/templates/base subfolder of one of the data paths given by jupyter --paths.