Prevent purely numeric template variables

[LilyFirefly]

Code of Conduct

• I agree to follow Django's Code of Conduct

Feature Description

Raise a TemplateSyntaxError for template variables (and filter or template tag arguments) that start as a numeric literal. For example {{ 1.a }}, {{ 2.3.1 }}, {% if 12.3.c %}.

Problem

Django always treats a template variable like {{ 1 }} or {{ 2.3 }} as a numeric literal, so it is impossible to use a context with purely numeric keys to look up values. For example, the "foo" string in { 1: "foo"} or {"1": "foo"} can never be looked up. This means it's much more likely that an example like {{ 1.2.3 }} or {{ 1.a }} is a mistake by the template author than an intentional attempt to look up {1: {2: {3: 4}}} or {"1": {"a": "foo"}}.

I don't think we should prevent examples such as {{ 1a }}, since this can be looked up in a context such as {"1a": "foo"}.

Request or proposal

proposal

Additional Details

I talk about this in my blog post. I also opened a Trac ticket, but was redirected here.

Implementation Suggestions

No response

[github-actions]

Thank you LilyFirefly for sharing your idea! We have a lot of them so please be patient. You can see the current queue here.

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Reaction Guide

• 👍 This is something I would use
• 👎 This is something that would cause problems for me or Django
• 😕 I’m indifferent to this
• 🎉 This is an easy win