📚 Doc: Add how to use NewCtxFunc and middleware at the same time

[JIeJaitt]

Description

Add documentation that tells users how to use both NewCtxFunc and app.Use().

Fixes #3319

Changes introduced

List the new features or adjustments introduced in this pull request. Provide details on benchmarks, documentation updates, changelog entries, and if applicable, the migration guide.

• Benchmarks: Describe any performance benchmarks and improvements related to the changes.
• Documentation Update: Detail the updates made to the documentation and links to the changed files.
• Changelog/What's New: Include a summary of the additions for the upcoming release notes.
• Migration Guide: If necessary, provide a guide or steps for users to migrate their existing code to accommodate these changes.
• API Alignment with Express: Explain how the changes align with the Express API.
• API Longevity: Discuss the steps taken to ensure that the new or updated APIs are consistent and not prone to breaking changes.
• Examples: Provide examples demonstrating the new features or changes in action.

Type of change

Please delete options that are not relevant.

• Documentation update (changes to documentation)

Checklist

Before you submit your pull request, please make sure you meet these requirements:

• Followed the inspiration of the Express.js framework for new functionalities, making them similar in usage.
• Conducted a self-review of the code and provided comments for complex or critical parts.
• Updated the documentation in the /docs/ directory for Fiber's documentation.
• Added or updated unit tests to validate the effectiveness of the changes or new features.
• Ensured that new and existing unit tests pass locally with the changes.
• Verified that any new dependencies are essential and have been agreed upon by the maintainers/community.
• Aimed for optimal performance with minimal allocations in the new code.
• Provided benchmarks for the new code to analyze and improve upon.

Commit formatting

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[coderabbitai]

Walkthrough

A new custom context with enhanced JSON response handling has been introduced. The changes add new structs and methods for response formatting and middleware control flow, as well as corresponding updates in documentation and tests. Additionally, a proxy test now leverages a dynamically created local proxy server for controlled testing. Overall, the modifications improve context management and ensure consistency across middleware execution and route handling.

Changes

File(s)	Change Summary
app_test.go	Added Response and testCustomCtx structs with new JSON and Next methods; introduced tests (Test_App_CustomCtx_With_Use) verifying JSON responses and middleware logging with/without middleware.
docs/api/app.md	Added "Using with Middleware" section; introduced a new CustomCtx type with an overridden Next method; updated main to showcase custom context creation and middleware integration.
middleware/proxy/proxy_test.go	Updated the proxy test to use a dynamically created proxy server instead of a hardcoded external URL; adjusted response assertions to expect "mock response" and renamed error variable for consistency.

Sequence Diagram(s)

sequenceDiagram
    participant Client
    participant CustomCtx
    participant Middleware
    participant RouteHandler

    Client->>CustomCtx: HTTP Request
    CustomCtx->>Middleware: Log context type (before Next)
    Middleware->>CustomCtx: Invoke Next()
    CustomCtx->>RouteHandler: Execute route handler
    RouteHandler-->>CustomCtx: Return response
    CustomCtx->>Middleware: Log context type (after Next)
    CustomCtx-->>Client: Send JSON Response (via Response struct)

Loading

Possibly related PRs

• 🔥 feat: Add Context Support to RequestID Middleware #3200: Adjusted context and Next method in request ID middleware, closely related to the custom context enhancements.
• 🔥 feat: Add End() method to Ctx #3280: Modified context handling and introduced response struct adjustments aligning with these new enhancements.
• 📚 Doc: Updates to Context documentation #3206: Updated the Next method in the Ctx interface documentation, directly related to the custom context modifications.

Suggested labels

📒 Documentation, v3

Suggested reviewers

• gaby
• sixcolors
• ReneWerner87
• efectn

Poem

In the garden of code, I hop with delight,
Custom contexts bloom in the soft moonlight.
JSON responses shine, so clear and neat,
While middleware flows in a rhythmic beat.
With a twitch of my ear, I celebrate tonight!
🐇🌟

---

📜 Recent review details

Configuration used: CodeRabbit UI
Review profile: CHILL
Plan: Pro

📥 Commits

Reviewing files that changed from the base of the PR and between c85ec75 and e2ad63e.

📒 Files selected for processing (3)

• app_test.go (1 hunks)
• docs/api/app.md (1 hunks)
• middleware/proxy/proxy_test.go (1 hunks)

🔇 Additional comments (5)

middleware/proxy/proxy_test.go (1)

504-521: Great improvement to test reliability and determinism!

Moving from using an external URL (Google) to a local mock server makes this test more reliable, faster, and less prone to network-related failures. The code is also more readable with consistent variable naming (err instead of err1).

docs/api/app.md (1)

559-607: Excellent documentation on preserving custom context types in middleware chains.

This clearly explains a previously undocumented but important pattern for using custom contexts with middleware. The example implementation of Next() properly maintains the context type throughout the request lifecycle by:

1. Incrementing the handler index
2. Managing flow between route and application handlers
3. Ensuring the custom context type is preserved after middleware calls

The documentation addresses issue #3319 effectively with a comprehensive example and clear explanations.

app_test.go (3)

1945-1949: Good addition of a standardized response structure.

This Response struct provides a consistent format for JSON responses, which improves API consistency.

---

1951-1976: Well-implemented custom context with proper middleware support.

The implementation correctly shows how to:

1. Extend the DefaultCtx with custom behavior
2. Override the JSON method to provide a standardized response format
3. Implement the Next() method to preserve context type throughout middleware execution

This is a good example that exactly matches the documentation in docs/api/app.md.

---

1978-2041: Comprehensive tests validating custom context behavior.

These tests effectively verify that the custom context works both with and without middleware, ensuring the custom JSON format is correctly applied in both scenarios. The explicit context type logging helps verify that the context type is properly preserved through middleware calls.

✨ Finishing Touches

• 📝 Generate Docstrings (Beta)

---

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[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 84.18%. Comparing base (c85ec75) to head (e2ad63e).
Report is 6 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #3328      +/-   ##
==========================================
- Coverage   84.25%   84.18%   -0.07%     
==========================================
  Files         116      116              
  Lines       11555    11555              
==========================================
- Hits         9736     9728       -8     
- Misses       1391     1397       +6     
- Partials      428      430       +2     

Flag	Coverage Δ
unittests	84.18% <ø> (-0.07%)	⬇️

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[JIeJaitt]

I didn't change this unit test function but it times out

[ReneWerner87]

thanks for that, as a user i would expect that this extra effort with the overlays of the next method is not necessary
@efectn Was that the intention?

[JIeJaitt]

thanks for that, as a user i would expect that this extra effort with the overlays of the next method is not necessary @efectn what do you say, is that what you want?

This is better, if there is no more discussion I will close this pr.

[efectn]

thanks for that, as a user i would expect that this extra effort with the overlays of the next method is not necessary @efectn Was that the intention?

I agree with you, i will check it