fixing bug where rendered response is evaluated twice, #357
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Pull Request Overview
This PR fixes a bug where generators in response data were being exhausted due to double evaluation during caching. The issue occurred because the cache decorator was using rendered_content which re-evaluates the response data instead of using the already-rendered content.
- Changes
response.rendered_contenttoresponse.contentin the cache decorator to prevent double rendering - Adds a comprehensive test case that demonstrates the generator exhaustion bug and verifies the fix
Reviewed Changes
Copilot reviewed 2 out of 2 changed files in this pull request and generated 1 comment.
| File | Description |
|---|---|
| rest_framework_extensions/cache/decorators.py | Changes cache decorator to use pre-rendered content instead of re-rendering |
| tests_app/tests/unit/cache/decorators/tests.py | Adds test case to verify generator exhaustion bug is fixed |
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| headers = {k: (k, v) for k, v in response.items()} | ||
| response_triple = ( | ||
| response.rendered_content, | ||
| response.content, # FIX: Use already-rendered content |
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The comment should be more descriptive about why this change is necessary. Consider: '# Use already-rendered content to avoid re-evaluating generators and other iterables'
Suggested change
| response.content, # FIX: Use already-rendered content | |
| response.content, # Use already-rendered content to avoid re-evaluating generators and other iterables |
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rendered_content and render both evaluate data. If data contains a generator it will be exhausted in the first render and won't make it into the cache