Sling Academy
Home/FastAPI/How to remove consecutive whitespace in rendered Jinja pages

How to remove consecutive whitespace in rendered Jinja pages

Last updated: November 28, 2024

When dealing with web development using Jinja, you may encounter situations where your templates have consecutive whitespace that affects the layout or styling of your rendered pages. Removing unnecessary whitespace is crucial to ensure your templates render cleanly and efficiently. In this article, we will demonstrate how to remove consecutive whitespace in Jinja templates.

Understanding Jinja Whitespace Control

Jinja provides a feature for trimming whitespaces, which can be used to clean up generated HTML. Here are a few simple ways to handle whitespace using Jinja syntax.

Using the minus sign (-) for blocks and variables

In Jinja, you can use - after a block, or variable delimiter. This will remove any whitespace around the block or variable. Let's see an example:

{% raw %}
{% for item in items -%}
    {{ item }}
{% endfor %}
{% endraw %}

In this example, the - minus sign ensures there's no whitespace added around the beginning or end of the for loop.

Controlling Newlines

If you want to remove newlines as well, you can use the minus sign at the start and the end of expressions:

{% raw %}
{{ item }}
{% endraw %}

In this snippet, Jinja will strip newlines/output spaces surrounding the loop. This ensures our <li> tags appear consecutively without additional empty lines or spaces.

Configuring Your Jinja Environment

Jinja also provides configuration options for controlling whitespace globally. This can be done when setting up your Jinja environment:

from jinja2 import Environment

env = Environment(trim_blocks=True, lstrip_blocks=True)

Here, trim_blocks=True removes newlines between tags, and lstrip_blocks=True removes any leading whitespace from the start of a line.

Conclusion

Managing whitespace in Jinja templates is crucial for clean output. Using the techniques described above, you can effectively remove unwanted whitespace on your pages, ensuring that your rendered HTML is both optimized for performance and visually appealing. Always test your templates to ensure that these transformations work as intended.

Next Article: Popular useful built-in Jinja filters you should know

Previous Article: How to format large numbers with thousand separators in Jinja template

Series: Jinja Templates

FastAPI

You May Also Like

  • Popular useful built-in Jinja filters you should know
  • How to format large numbers with thousand separators in Jinja template
  • How to format date time in Jinja templates
  • FastAPI + Jinja: How to create custom filters
  • How to pass variables from Python (FastAPI) to Jinja
  • How to decode Jinja response to string
  • How to create and use macros in Jinja
  • How to use namespace in Jinja
  • How to use if/ else in Jinja
  • How to use loops in Jinja
  • FastAPI + SQLAlchemy: Using cursor-based pagination
  • FastAPI: How to use macros in Jinja templates
  • Fixing Common Swagger UI Errors in FastAPI
  • FastAPI Error: 307 Temporary Redirect – Causes and Solutions
  • FastAPI Error: Expected UploadFile, received ‘str’
  • Resolving FastAPI ImportError: No Known Parent Package
  • FastAPI Error: No module named ‘pydantic_core._pydantic_core’
  • Resolving FastAPI 422 Error: Value is not a valid dict
  • Resolving the FastAPI Circular References Error