{"record":{"id":"a2d9ab5d566f623a","repo":"kataras/iris","slug":"s-parameter-type-s-should-be-registered-to-th","errorCode":null,"errorMessage":"%s: parameter type \"%s\" should be registered to the very end of a path once","messagePattern":"(.+?): parameter type \"(.+?)\" should be registered to the very end of a path once","errorType":"exception","errorClass":null,"httpStatus":null,"severity":"error","filePath":"macro/interpreter/parser/parser.go","lineNumber":59,"sourceCode":"\t\t\tif idx := strings.LastIndexByte(s, lexer.End); idx > 2 && idx < len(s)-1 /* at least {x}*/ {\n\t\t\t\t// Do NOT allow something more than a dynamic path parameter in the same path segment,\n\t\t\t\t// e.g. /{param}-other-static-part/. See #2024.\n\t\t\t\t// this allows it but NO (see trie insert): s = s[0 : idx+1]\n\t\t\t\treturn nil, fmt.Errorf(\"%s: invalid path part: dynamic path parameter and other parameters or static parts are not allowed in the same exact request path part, use the {regexp} function alone instead\", s)\n\t\t\t} else {\n\t\t\t\tcontinue\n\t\t\t}\n\t\t}\n\n\t\tp.Reset(s)\n\t\tstmt, err := p.Parse(paramTypes)\n\t\tif err != nil {\n\t\t\t// exit on first error\n\t\t\treturn nil, err\n\t\t}\n\t\t// if we have param type path but it's not the last path part\n\t\tif ast.IsTrailing(stmt.Type) && i < len(pathParts)-1 {\n\t\t\treturn nil, fmt.Errorf(\"%s: parameter type \\\"%s\\\" should be registered to the very end of a path once\", s, stmt.Type.Indent())\n\t\t}\n\n\t\tstatements = append(statements, stmt)\n\t}\n\n\treturn statements, nil\n}\n\n// ParamParser is the parser\n// which is being used by the Parse function\n// to parse path segments one by one\n// and return their parsed parameter statements (param name, param type its functions and the inline route's functions).\ntype ParamParser struct {\n\tsrc    string\n\terrors []string\n}\n\n// NewParamParser receives a \"src\" of a single parameter","sourceCodeStart":41,"sourceCodeEnd":77,"githubUrl":"https://github.com/kataras/iris/blob/7bedaf55a0b64bbb2248a5845a2c60d81a30996a/macro/interpreter/parser/parser.go#L41-L77","documentation":"Parse enforces that a trailing parameter type ({param:path}, the wildcard type) can only appear as the very last path segment. '%s: parameter type \\\"%s\\\" should be registered to the very end of a path once' fires when ast.IsTrailing(stmt.Type) is true but more path parts follow.","triggerScenarios":"Registering routes like /static/{p:path}/index or /files/{f:path}/download — the :path (wildcard) param is followed by another segment. Detected at build time via Parse.","commonSituations":"Migrating wildcard routes from other frameworks that allow mid-path wildcards; typos leaving extra segments after a catch-all; generated routes appending suffixes after {param:path}.","solutions":["Move the {param:path} declaration to the final segment of the route.","Handle any trailing differentiation inside the handler by inspecting the wildcard value.","If both a specific sub-path and wildcard are needed, register them as separate routes (/files/{p:path} and /files/special)."],"exampleFix":"// before\napp.Handle(\"/assets/{p:path}/index\", serveIndex)\n// after\napp.Handle(\"/assets/{p:path}\", serveAssets) // inspect p in handler\n","handlingStrategy":"validation","validationCode":"func wildcardIsLast(p string) bool {\n    parts := strings.Split(strings.Trim(p, \"/\"), \"/\")\n    for i, s := range parts {\n        if strings.Contains(s, \":path}\") && i != len(parts)-1 {\n            return false\n        }\n    }\n    return true\n}","typeGuard":"func isTrailingWildcardSegment(s string) bool { return strings.HasSuffix(s, \":path}\") }","tryCatchPattern":"if err := app.Build(); err != nil && strings.Contains(err.Error(), \"should be registered to the very end\") {\n    log.Fatalf(\"move wildcard param to the last segment: %v\", err)\n}","preventionTips":["Convention: {param:path} always last in route patterns.","Differentiate sub-paths with separate route registrations.","Test wildcard routes at build time in CI."],"tags":["go","iris","routing","wildcard","path-parameters"],"backgroundTag":"wildcard-param-not-last","analyzedSha":"7bedaf55a0b64bbb2248a5845a2c60d81a30996a","analyzedAt":"2026-08-30T20:38:16.250Z","schemaVersion":2},"datasetVersion":"2026-08-30T23:17:21.991Z"}