Custom pages and templates#

Datasette provides a number of ways of customizing the way data is displayed.

Custom CSS and JavaScript#

When you launch Datasette, you can specify a custom metadata file like this:

datasette mydb.db --metadata metadata.yaml

Your metadata.yaml file can include links that look like this:

  "extra_css_urls": [
  "extra_js_urls": [

The extra CSS and JavaScript files will be linked in the <head> of every page:

<link rel="stylesheet" href="">
<script src=""></script>

You can also specify a SRI (subresource integrity hash) for these assets:

- url:
  sri: sha384-9qIZekWUyjCyDIf2YK1FRoKiPJq4PHt6tp/ulnuuyRBvazd0hG7pWbE99zvwSznI
- url:
  sri: sha256-k2WSCIexGzOj3Euiig+TlR8gA0EmPjuc79OEeY5L45g=
  "extra_css_urls": [
      "url": "",
      "sri": "sha384-9qIZekWUyjCyDIf2YK1FRoKiPJq4PHt6tp/ulnuuyRBvazd0hG7pWbE99zvwSznI"
  "extra_js_urls": [
      "url": "",
      "sri": "sha256-k2WSCIexGzOj3Euiig+TlR8gA0EmPjuc79OEeY5L45g="

This will produce:

<link rel="stylesheet" href=""
<script src=""

Modern browsers will only execute the stylesheet or JavaScript if the SRI hash matches the content served. You can generate hashes using

Items in "extra_js_urls" can specify "module": true if they reference JavaScript that uses JavaScript modules. This configuration:

- url:
  module: true
  "extra_js_urls": [
      "url": "",
      "module": true

Will produce this HTML:

<script type="module" src=""></script>

CSS classes on the <body>#

Every default template includes CSS classes in the body designed to support custom styling.

The index template (the top level page at /) gets this:

<body class="index">

The database template (/dbname) gets this:

<body class="db db-dbname">

The custom SQL template (/dbname?sql=...) gets this:

<body class="query db-dbname">

A canned query template (/dbname/queryname) gets this:

<body class="query db-dbname query-queryname">

The table template (/dbname/tablename) gets:

<body class="table db-dbname table-tablename">

The row template (/dbname/tablename/rowid) gets:

<body class="row db-dbname table-tablename">

The db-x and table-x classes use the database or table names themselves if they are valid CSS identifiers. If they aren't, we strip any invalid characters out and append a 6 character md5 digest of the original name, in order to ensure that multiple tables which resolve to the same stripped character version still have different CSS classes.

Some examples:

"simple" => "simple"
"MixedCase" => "MixedCase"
"-no-leading-hyphens" => "no-leading-hyphens-65bea6"
"_no-leading-underscores" => "no-leading-underscores-b921bc"
"no spaces" => "no-spaces-7088d7"
"-" => "336d5e"
"no $ characters" => "no--characters-59e024"

<td> and <th> elements also get custom CSS classes reflecting the database column they are representing, for example:

            <th class="col-id" scope="col">id</th>
            <th class="col-name" scope="col">name</th>
            <td class="col-id"><a href="...">1</a></td>
            <td class="col-name">SMITH</td>

Serving static files#

Datasette can serve static files for you, using the --static option. Consider the following directory structure:


You can start Datasette using --static assets:static-files/ to serve those files from the /assets/ mount point:

datasette -m metadata.json --static assets:static-files/ --memory

The following URLs will now serve the content from those CSS and JS files:


You can reference those files from metadata.json like so:

- /assets/styles.css
- /assets/app.js
  "extra_css_urls": [
  "extra_js_urls": [

Publishing static assets#

The datasette publish command can be used to publish your static assets, using the same syntax as above:

datasette publish cloudrun mydb.db --static assets:static-files/

This will upload the contents of the static-files/ directory as part of the deployment, and configure Datasette to correctly serve the assets from /assets/.

Custom templates#

By default, Datasette uses default templates that ship with the package.

You can over-ride these templates by specifying a custom --template-dir like this:

datasette mydb.db --template-dir=mytemplates/

Datasette will now first look for templates in that directory, and fall back on the defaults if no matches are found.

It is also possible to over-ride templates on a per-database, per-row or per- table basis.

The lookup rules Datasette uses are as follows:

Index page (/):

Database page (/mydatabase):

Custom query page (/mydatabase?sql=...):

Canned query page (/mydatabase/canned-query):

Table page (/mydatabase/mytable):

Row page (/mydatabase/mytable/id):

Table of rows and columns include on table page:

Table of rows and columns include on row page:

If a table name has spaces or other unexpected characters in it, the template filename will follow the same rules as our custom <body> CSS classes - for example, a table called "Food Trucks" will attempt to load the following templates:


You can find out which templates were considered for a specific page by viewing source on that page and looking for an HTML comment at the bottom. The comment will look something like this:

<!-- Templates considered: *query-mydb-tz.html, query-mydb.html, query.html -->

This example is from the canned query page for a query called "tz" in the database called "mydb". The asterisk shows which template was selected - so in this case, Datasette found a template file called query-mydb-tz.html and used that - but if that template had not been found, it would have tried for query-mydb.html or the default query.html.

It is possible to extend the default templates using Jinja template inheritance. If you want to customize EVERY row template with some additional content you can do so by creating a row.html template like this:

{% extends "default:row.html" %}

{% block content %}
<p>This line renders the original block:</p>
{{ super() }}
{% endblock %}

Note the default:row.html template name, which ensures Jinja will inherit from the default template.

The _table.html template is included by both the row and the table pages, and a list of rows. The default _table.html template renders them as an HTML template and can be seen here.

You can provide a custom template that applies to all of your databases and tables, or you can provide custom templates for specific tables using the template naming scheme described above.

If you want to present your data in a format other than an HTML table, you can do so by looping through display_rows in your own _table.html template. You can use {{ row["column_name"] }} to output the raw value of a specific column.

If you want to output the rendered HTML version of a column, including any links to foreign keys, you can use {{ row.display("column_name") }}.

Here is an example of a custom _table.html template:

{% for row in display_rows %}
        <h2>{{ row["title"] }}</h2>
        <p>{{ row["description"] }}<lp>
        <p>Category: {{ row.display("category_id") }}</p>
{% endfor %}

Custom pages#

You can add templated pages to your Datasette instance by creating HTML files in a pages directory within your templates directory.

For example, to add a custom page that is served at http://localhost/about you would create a file in templates/pages/about.html, then start Datasette like this:

datasette mydb.db --template-dir=templates/

You can nest directories within pages to create a nested structure. To create a http://localhost:8001/about/map page you would create templates/pages/about/map.html.

Path parameters for pages#

You can define custom pages that match multiple paths by creating files with {variable} definitions in their filenames.

For example, to capture any request to a URL matching /about/*, you would create a template in the following location:


A hit to /about/news would render that template and pass in a variable called slug with a value of "news".

If you use this mechanism don't forget to return a 404 if the referenced content could not be found. You can do this using {{ raise_404() }} described below.

Templates defined using custom page routes work particularly well with the sql() template function from datasette-template-sql or the graphql() template function from datasette-graphql.

Custom headers and status codes#

Custom pages default to being served with a content-type of text/html; charset=utf-8 and a 200 status code. You can change these by calling a custom function from within your template.

For example, to serve a custom page with a 418 I'm a teapot HTTP status code, create a file in pages/teapot.html containing the following:

{{ custom_status(418) }}
I'm a teapot

To serve a custom HTTP header, add a custom_header(name, value) function call. For example:

{{ custom_status(418) }}
{{ custom_header("x-teapot", "I am") }}
I'm a teapot

You can verify this is working using curl like this:

curl -I ''
HTTP/1.1 418
date: Sun, 26 Apr 2020 18:38:30 GMT
server: uvicorn
x-teapot: I am
content-type: text/html; charset=utf-8

Returning 404s#

To indicate that content could not be found and display the default 404 page you can use the raise_404(message) function:

{% if not rows %}
    {{ raise_404("Content not found") }}
{% endif %}

If you call raise_404() the other content in your template will be ignored.

Custom redirects#

You can use the custom_redirect(location) function to redirect users to another page, for example in a file called pages/datasette.html:

{{ custom_redirect("") }}

Now requests to http://localhost:8001/datasette will result in a redirect.

These redirects are served with a 302 Found status code by default. You can send a 301 Moved Permanently code by passing 301 as the second argument to the function:

{{ custom_redirect("", 301) }}

Custom error pages#

Datasette returns an error page if an unexpected error occurs, access is forbidden or content cannot be found.

You can customize the response returned for these errors by providing a custom error page template.

Content not found errors use a 404.html template. Access denied errors use 403.html. Invalid input errors use 400.html. Unexpected errors of other kinds use 500.html.

If a template for the specific error code is not found a template called error.html will be used instead. If you do not provide that template Datasette's default error.html template will be used.

The error template will be passed the following context:

status - integer

The integer HTTP status code, e.g. 404, 500, 403, 400.

error - string

Details of the specific error, usually a full sentence.

title - string or None

A title for the page representing the class of error. This is often None for errors that do not provide a title separate from their error message.