🔥 feat: Add URL() method to Route for generating URLs with parameters

[Claude]

Description

Adds a new Route.URL(params Map) (string, error) API for generating relative URLs directly from named routes with parameter substitution.

This change lets users construct URLs programmatically from app.GetRoute(name) without going through Ctx.GetRouteURL(), while keeping behavior aligned with existing named-route URL generation. Follow-up review feedback refined the implementation so URL generation is deterministic, respects route-level case sensitivity, handles mounted sub-app routes correctly, prefers the matching greedy token type for + vs *, gracefully falls back to route.Path when a route has no parsed segments, avoids per-call allocations in greedy fallback lookup by using precomputed string key orders, and uses a value receiver so the common call pattern app.GetRoute(name).URL(params) compiles directly.

app.Get("/user/:name/:id", handler).Name("user")

url, err := app.GetRoute("user").URL(fiber.Map{"name": "john", "id": "123"})
// Returns: "/user/john/123"

Changes introduced

• Benchmarks: The implementation continues to use bytebufferpool for efficient string building with minimal allocations, and the greedy fallback lookup now uses precomputed string key orders to avoid repeated hot-path string conversions and extra allocations.
• Documentation Update: Added public documentation for generating URLs from routes via app.GetRoute(name) in docs/api/app.md, added a release-note entry in docs/whats_new.md, and refined the router.go godoc for Route.URL() to reflect direct app.GetRoute(name).URL(params) usage.
• Changelog/What's New: Documented that named routes retrieved with app.GetRoute(name) now support route.URL(params) for parameterized URL generation, including named, wildcard (*), and plus (+) segments.
• Migration Guide: Not required. This is a non-breaking additive API.
• API Alignment with Express: Route.URL() complements Fiber’s existing named-route helpers in an Express-like style by letting callers generate route URLs directly from route metadata.
• API Longevity: The method signature matches existing c.GetRouteURL() conventions by returning (string, error). The implementation was refactored to a shared buildRouteURL(route, params) helper used by both Route.URL() and DefaultRes.getLocationFromRoute() so behavior stays consistent across APIs, and Route.URL() now uses a value receiver to match app.GetRoute() returning a Route value.
• Examples: Supports standard params, wildcard params, greedy plus params, deterministic exact-match precedence, direct app.GetRoute(name).URL(params) calls, and route fallback behavior when only Path is available.

Additional adjustments included in this PR:

• Added caseSensitive handling to Route so Route.URL() respects route registration and mounted sub-app behavior.
• Parameter resolution is deterministic: exact match → case-insensitive lexicographically-smallest fallback (when !caseSensitive) → greedy fallback.
• Greedy fallback now prefers + for plus params and * for wildcard params before falling back to the alternate token for compatibility.
• Greedy fallback lookup uses precomputed default and preferred string key orders to avoid per-call byte→string conversions in URL generation hot paths.
• Route.URL() returns ErrNotFound for empty/zero-value routes and returns route.Path when a route has no parsed segments.
• Added and expanded tests covering direct app.GetRoute(name).URL(...) usage, case-sensitive and case-insensitive behavior, exact-match precedence, greedy + handling, default greedy fallback selection, and no-parser fallback routes.

Type of change

• New feature (non-breaking change which adds functionality)
• Enhancement (improvement to existing features and functionality)
• Documentation update (changes to documentation)
• Performance improvement (non-breaking change which improves efficiency)
• Code consistency (non-breaking change which improves code reliability and robustness)

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

Please use emojis in commit messages for an easy way to identify the purpose or intention of a commit. Check out the emoji cheatsheet here: CONTRIBUTING.md

[codecov]

Codecov Report

❌ Patch coverage is 91.37931% with 5 lines in your changes missing coverage. Please review.
✅ Project coverage is 91.21%. Comparing base (6c19f48) to head (9f828e7).

Files with missing lines	Patch %	Lines
router.go	92.85%	2 Missing and 2 partials ⚠️
res.go	50.00%	0 Missing and 1 partial ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #4195      +/-   ##
==========================================
+ Coverage   91.16%   91.21%   +0.04%     
==========================================
  Files         123      123              
  Lines       11855    11885      +30     
==========================================
+ Hits        10808    10841      +33     
+ Misses        659      657       -2     
+ Partials      388      387       -1     

Flag	Coverage Δ
unittests	91.21% <91.37%> (+0.04%)	⬆️

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[Copilot]

Pull request overview

Adds a new Route.URL(params Map) (string, error) API to generate relative URLs from a route’s parsed path segments by substituting route parameters, aligning with existing named-route URL generation patterns in the codebase.

Changes:

• Introduces (*Route).URL() to build URLs from routeParser segments with parameter substitution (including wildcards/greedy params).
• Adds unit tests for Route.URL() covering common parameter and wildcard cases.
• Updates generated Ctx/Res interface docs for End() with a streaming-related note.

Reviewed changes

Copilot reviewed 4 out of 4 changed files in this pull request and generated 5 comments.

File	Description
router.go	Adds Route.URL() implementation using routeParser segments and bytebuffer pooling.
router_test.go	Adds Test_Route_URL subtests for parameter substitution behavior.
res_interface_gen.go	Updates generated Res interface docs for End().
ctx_interface_gen.go	Updates generated Ctx interface docs for End().

[gaby]

@copilot apply changes based on the comments in this thread

[Copilot]

@copilot apply changes based on the comments in this thread

Applied all review feedback in commit 26faa1d:

1. Case sensitivity: Added caseSensitive field to Route, set at registration time from app.config.CaseSensitive and copied in copyRoute(). Route.URL() now respects this setting, consistent with getLocationFromRoute()/GetRouteURL().

2. Deterministic lookup: Refactored to: exact key match → case-insensitive fallback (when !caseSensitive) → greedy parameter fallback (*/+). No more non-deterministic map iteration for matching.

3. Case-sensitive test: Added "case sensitive" subtest using Config{CaseSensitive: true} that verifies exact match succeeds and mismatched case does not match.

4. Generated files: Reverted unintended changes to ctx_interface_gen.go and res_interface_gen.go.

[Copilot]

Pull request overview

Copilot reviewed 2 out of 2 changed files in this pull request and generated 3 comments.

[gaby]

@copilot apply changes based on the comments in this thread

[Copilot]

@copilot apply changes based on the comments in this thread

Applied all three review comments in commit 6b37d8d:

1. Nil guard (router.go:82): Route.URL() now checks r == nil before accessing fields, returning ErrNotFound — consistent with getLocationFromRoute().

2. Deterministic case-insensitive fallback (router.go:105-115): When multiple keys case-fold to the same param name, the lexicographically-smallest key wins (via key < matchedKey), eliminating non-determinism from map iteration.

3. Mounted route caseSensitive (router.go:442): addPrefixToRoute() now sets route.caseSensitive = app.config.CaseSensitive, so cloned sub-app routes adopt the parent app's case-sensitivity when re-parsed/registered.

Also added a "nil route" test case.

[gaby]

@copilot Your latest changes broke unit tests.

[Copilot]

@copilot Your latest changes broke unit tests.

I investigated this before making any speculative changes. The exact workflow-style unit run (gotestsum -- ./... -race -count=1 -shuffle=on) passes locally on afc8c17, so the latest Route.URL receiver change does not reproduce a deterministic unit failure here. The only failure I could reproduce is in the repeated stress run (-count=15 -shuffle=on), where a pre-existing flaky test in the root package (Test_App_Test_Goroutine_Leak_Compare) trips intermittently; the CI logs also showed unrelated intermittent failures in other packages. I haven’t changed code based on this comment because I couldn’t tie a stable failing test to the Route.URL change.

[gaby]

@ReneWerner87 let me run copilot once more here before merging

[Copilot]

Pull request overview

Copilot reviewed 6 out of 6 changed files in this pull request and generated 1 comment.

[gaby]

/gemini review

[gemini-code-assist]

Code Review

This pull request introduces the URL method to the Route struct, enabling the generation of relative URLs from named routes with support for parameter substitution, including named, wildcard, and plus segments. The implementation refactors existing logic into a shared buildRouteURL helper and respects the application's case-sensitivity configuration. Feedback identifies a logic bug in the case-insensitive parameter matching that leads to non-deterministic results and suggests simplifying redundant variable declarations.

[gaby]

@copilot There's a bug in the case-insensitive parameter matching logic. The found variable from the outer scope is updated within the loop, which prevents the code from correctly finding the lexicographically smallest matching key as intended. Instead, it picks the first key that matches case-insensitively based on map iteration order, leading to non-deterministic behavior.

To fix this, you should use a local boolean flag within this block to track if a match has been found.

			// Fall back to a case-insensitive match using a deterministic winner
			var matchedKey string
			foundMatch := false
			for key := range params {
				if utils.EqualFold(key, segment.ParamName) && (!foundMatch || key < matchedKey) {
					matchedKey = key
					foundMatch = true
				}
			}
			if foundMatch {
				val = params[matchedKey]
				found = true
			}

[Copilot]

@copilot There's a bug in the case-insensitive parameter matching logic. The found variable from the outer scope is updated within the loop, which prevents the code from correctly find...

Fixed in 77044e2. I updated the case-insensitive fallback to use a local foundMatch flag so it deterministically picks the lexicographically smallest matching key, and added regression coverage in Test_Route_URL to lock this behavior in.