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@jonluca jonluca commented Jul 26, 2025

Fix: Prioritize exact path matches over parameterized paths in tRPC-to-OpenAPI adapter

Problem

The tRPC-to-OpenAPI adapter was incorrectly matching parameterized routes before exact path matches, causing conflicts when both types of routes exist for the same base path. For example, with routes /image-lora-models/search and /image-lora-models/{id}, requests to /image-lora-models/search were being incorrectly matched by the parameterized route /image-lora-models/{id}.

Root Cause

The original implementation used a single cache with regex patterns for all routes. When matching paths, it would iterate through all regex patterns and return the first match, regardless of whether it was an exact or parameterized route. This meant that parameterized routes could incorrectly match exact paths.

Solution

Split the procedure cache into two separate caches with priority-based matching:

  1. Exact Path Cache: Stores non-parameterized routes using string keys for O(1) lookup
  2. Parameterized Path Cache: Stores routes with path parameters using regex patterns

Implementation Details

Before

// Single cache with regex patterns
const procedureCache = new Map<
  OpenApiMethod | "HEAD",
  Map<RegExp, ProcedureInfo>
>();

// Matching logic - first regex match wins
const procedureRegExp = Array.from(procedureMethodCache.keys())
  .find((re) => re.test(path));

After

// Dual cache structure
const exactPathCache = new Map<
  OpenApiMethod | "HEAD", 
  Map<string, ProcedureInfo>
>();
const parameterizedPathCache = new Map<
  OpenApiMethod | "HEAD",
  Map<RegExp, ProcedureInfo>
>();

// Priority-based matching
// 1. Check exact matches first (O(1))
const exactMatch = exactPathCache.get(method)?.get(path);
if (exactMatch) return exactMatch;

// 2. Fall back to parameterized matches
const parameterizedMatch = findParameterizedMatch(path);

Examples

Route Definitions

// These routes would conflict with the old implementation
router.query({
  path: "/image-lora-models/search",
  // ... search logic
});

router.query({
  path: "/image-lora-models/{id}",
  // ... get by id logic
});

Request Matching

Request Path Old Behavior New Behavior
/image-lora-models/search ❌ Matches {id} route ✅ Matches search route
/image-lora-models/123 ✅ Matches {id} route ✅ Matches {id} route
/image-lora-models/abc ✅ Matches {id} route ✅ Matches {id} route

Benefits

  1. Correctness: Exact paths are now properly prioritized over parameterized paths
  2. Performance: Exact path matching is now O(1) instead of O(n) regex testing
  3. Maintainability: Clear separation between exact and parameterized route handling
  4. Backward Compatibility: All existing functionality is preserved

Testing

  • ✅ Exact paths match their intended routes
  • ✅ Parameterized paths still work correctly
  • ✅ No performance regression for existing routes
  • ✅ Improved performance for exact path matches

When two paths might collide (like /route/search and /route/{id}), we want to match the non-param based routes first, and then only match the param based route if a non param route exists.
@mcampa
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Owner

mcampa commented Aug 1, 2025

Hey @jonluca thanks for the fix. Can you take a look at why the test is failing?

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2 participants