Fix wildcard path patterns in OpenAPI spec output for known routers

openapi.go

@@ -5,6 +5,8 @@ import (
 	"encoding/json"
 	"net/http"
 	"reflect"
+	"regexp"
+	"strings"
 	"time"
 
 	"github.com/danielgtaylor/huma/v2/yaml"
@@ -1541,7 +1543,7 @@ func (o *OpenAPI) MarshalJSON() ([]byte, error) {
 		{"info", o.Info, omitNever},
 		{"jsonSchemaDialect", o.JSONSchemaDialect, omitEmpty},
 		{"servers", o.Servers, omitEmpty},
-		{"paths", o.Paths, omitEmpty},
+		{"paths", FixWildcardPaths(o.Paths), omitEmpty},
 		{"webhooks", o.Webhooks, omitEmpty},
 		{"components", o.Components, omitEmpty},
 		{"security", o.Security, omitNil},
@@ -1677,3 +1679,77 @@ func (o *OpenAPI) DowngradeYAML() ([]byte, error) {
 	}
 	return buf.Bytes(), err
 }
+
+// Patterns for router-specific wildcards
+var (
+	// Matches {name...} (ServeMux)
+	serveMuxWildcard = regexp.MustCompile(`\{([^}]+)\.\.\.}`)
+	// Matches {name:.*} (Gorilla Mux)
+	gorillaMuxWildcard = regexp.MustCompile(`\{([^:}]+):\.\*}`)
+	// Matches *name at end of path (Gin, HttpRouter, BunRouter)
+	starNameWildcard = regexp.MustCompile(`/\*([a-zA-Z_][a-zA-Z0-9_]*)$`)
+)
+
+// fixWildcardPath converts router-specific wildcard patterns to OpenAPI-compatible path parameters
+func fixWildcardPath(path string) string {
+	// ServeMux: {name...} -> {name}
+	if replaced := serveMuxWildcard.ReplaceAllString(path, "{$1}"); replaced != path {
+		return replaced
+	}
+
+	// Gorilla Mux: {name:.*} -> {name}
+	if replaced := gorillaMuxWildcard.ReplaceAllString(path, "{$1}"); replaced != path {
+		return replaced
+	}
+
+	// Gin, HttpRouter, BunRouter: /*name -> /{name}
+	if replaced := starNameWildcard.ReplaceAllString(path, "/{$1}"); replaced != path {
+		return replaced
+	}
+
+	// Chi, Echo, Fiber: trailing /* or /+ -> /{path}
+	if strings.HasSuffix(path, "/*") {
+		return strings.TrimSuffix(path, "/*") + "/{path}"
+	}
+	if strings.HasSuffix(path, "/+") {
+		return strings.TrimSuffix(path, "/+") + "/{path}"
+	}
+
+	// No match, return original
+	return path
+}
+
+// FixWildcardPaths returns a copy of the paths map with wildcard patterns normalized for OpenAPI.
+//
+// Different routers use different syntax for wildcard/catch-all path parameters
+// (e.g., {path...}, /*name, /*, /+), but the OpenAPI specification only supports
+// the standard {paramName} format. This function transforms router-specific
+// wildcard patterns into OpenAPI-compatible path parameters.
+//
+// This transformation is applied during JSON marshaling of the OpenAPI spec,
+// so the internal Paths map retains the original router-specific patterns for
+// correct request routing, while the generated OpenAPI document uses standard
+// path parameter syntax for compatibility with OpenAPI tools and clients.
+//
+// The PathItem values are preserved (same pointer references), only the map keys
+// are transformed.
+func FixWildcardPaths(paths map[string]*PathItem) map[string]*PathItem {
+	if paths == nil {
+		return nil
+	}
+	fixed := make(map[string]*PathItem, len(paths))
+	for path, item := range paths {
+		normalized := fixWildcardPath(path)
+
+		// If normalization causes a collision (multiple original paths mapping
+		// to the same normalized key), fall back to the original path to avoid
+		// silently dropping routes from the OpenAPI spec.
+		if _, exists := fixed[normalized]; exists && normalized != path {
+			fixed[path] = item
+			continue
+		}
+
+		fixed[normalized] = item
+	}
+	return fixed
+}

openapi_test.go

@@ -265,3 +265,73 @@ func TestDowngrade(t *testing.T) {
 	// Check that the downgrade worked as expected.
 	assert.JSONEq(t, expected, string(v30))
 }
+
+func TestFixWildcardPaths(t *testing.T) {
+	// Create distinct PathItem pointers so we can verify they are preserved
+	pathItems := make([]*huma.PathItem, 14)
+	for i := range pathItems {
+		pathItems[i] = &huma.PathItem{}
+	}
+
+	input := map[string]*huma.PathItem{
+		// ServeMux
+		"/api/{path...}":       pathItems[0],
+		"/files/{filepath...}": pathItems[1],
+		// Gorilla Mux
+		"/mux/{path:.*}":    pathItems[2],
+		"/mux/v1/{rest:.*}": pathItems[3],
+		// Gin, HttpRouter, BunRouter
+		"/gin/*filepath":   pathItems[4],
+		"/router/v1/*rest": pathItems[5],
+		// Chi, Echo
+		"/chi/*":         pathItems[6],
+		"/echo/static/*": pathItems[7],
+		// Fiber
+		"/fiber/+":        pathItems[8],
+		"/fiber/assets/+": pathItems[9],
+		// No wildcard (unchanged)
+		"/users/{id}":   pathItems[10],
+		"/api/v1/items": pathItems[11],
+		// Collision with existing path (should never happen in practice)
+		"/collision/{path}":    pathItems[12],
+		"/collision/{path...}": pathItems[13],
+	}
+
+	// Map from expected output path to the expected PathItem pointer
+	expected := map[string]*huma.PathItem{
+		// ServeMux
+		"/api/{path}":       pathItems[0],
+		"/files/{filepath}": pathItems[1],
+		// Gorilla Mux
+		"/mux/{path}":    pathItems[2],
+		"/mux/v1/{rest}": pathItems[3],
+		// Gin, HttpRouter, BunRouter
+		"/gin/{filepath}":   pathItems[4],
+		"/router/v1/{rest}": pathItems[5],
+		// Chi, Echo
+		"/chi/{path}":         pathItems[6],
+		"/echo/static/{path}": pathItems[7],
+		// Fiber
+		"/fiber/{path}":        pathItems[8],
+		"/fiber/assets/{path}": pathItems[9],
+		// No wildcard (unchanged)
+		"/users/{id}":   pathItems[10],
+		"/api/v1/items": pathItems[11],
+		// Collision with existing path (should never happen in practice)
+		"/collision/{path}":    pathItems[12], // original remains
+		"/collision/{path...}": pathItems[13], // unchanged (conflict)
+	}
+
+	result := huma.FixWildcardPaths(input)
+
+	require.Len(t, result, len(expected), "result should have same number of paths")
+
+	for path, expectedItem := range expected {
+		actualItem, exists := result[path]
+		assert.True(t, exists, "expected path not in result: %q", path)
+		assert.Same(t, expectedItem, actualItem, "PathItem for path %q should be preserved", path)
+	}
+
+	// Test nil input
+	assert.Nil(t, huma.FixWildcardPaths(nil))
+}