feat: flag to allow converting from yaml to json pre validation

Author: reversearrow

README.md

@@ -31,8 +31,12 @@ go get github.com/pb33f/libopenapi-validator
 ## Validate OpenAPI Document
 
 ```bash
-go run github.com/pb33f/libopenapi-validator/cmd/validate@latest [--regexengine] <file>
+go run github.com/pb33f/libopenapi-validator/cmd/validate@latest [--regexengine] [--yaml2json] <file>
 ```
+
+### Options
+
+#### --regexengine
 🔍 Example: Use a custom regex engine/flag (e.g., ecmascript)
 ```bash
 go run github.com/pb33f/libopenapi-validator/cmd/validate@latest --regexengine=ecmascript <file>
@@ -51,6 +55,26 @@ go run github.com/pb33f/libopenapi-validator/cmd/validate@latest --regexengine=e
 - re2
 - unicode
 
+#### --yaml2json
+🔍 Convert YAML files to JSON before validation (ℹ️ Default: false)
+
+[libopenapi](https://github.com/pb33f/libopenapi/blob/main/datamodel/spec_info.go#L115) passes `map[interface{}]interface{}` structures for deeply nested objects or complex mappings in the OpenAPI specification, which are not allowed in JSON.
+These structures cannot be properly converted to JSON by libopenapi and cannot be validated by jsonschema, resulting in ambiguous errors.
+
+This flag allows pre-converting from YAML to JSON to bypass this limitation of the libopenapi.
+
+**When does this happen?**
+- OpenAPI specs with deeply nested schema definitions
+- Complex `allOf`, `oneOf`, or `anyOf` structures with multiple levels
+- Specifications with intricate object mappings in examples or schema properties
+
+Enabling this flag pre-converts the YAML document from YAML to JSON, ensuring a clean JSON structure before validation.
+
+Example:
+```bash
+go run github.com/pb33f/libopenapi-validator/cmd/validate@latest --yaml2json <file>
+```
+
 ## Documentation
 
 - [The structure of the validator](https://pb33f.io/libopenapi/validation/#the-structure-of-the-validator)

cmd/validate/main.go

@@ -8,6 +8,7 @@ import (
 	"os"
 
 	"github.com/dlclark/regexp2"
+	"github.com/goccy/go-yaml"
 	"github.com/pb33f/libopenapi"
 	"github.com/santhosh-tekuri/jsonschema/v6"
 
@@ -64,13 +65,19 @@ var (
                          If not specified, the default libopenapi option is "re2".
 
 If not specified, the default libopenapi regex engine is "re2"".`)
+	convertYAMLToJSON = flag.Bool("yaml2json", false, `Convert YAML files to JSON before validation.
+						libopenapi passes map[interface{}]interface{} structures for deeply nested objects
+						or complex mappings, which are not allowed in JSON and cannot be validated by jsonschema.
+						This flag allows pre-converting from YAML to JSON to bypass this limitation of the libopenapi.
+						Default is false.`)
 )
 
 // main is the entry point for validating an OpenAPI Specification (OAS) document.
 // It uses the libopenapi-validator library to check if the provided OAS document
 // conforms to the OpenAPI specification.
 //
-// This tool accepts a single input file (YAML or JSON) and provides an optional
+// This tool accepts a single input file (YAML or JSON) and provides optional flags:
+//
 // `--regexengine` flag to customize the regex engine used during validation.
 // This is useful for cases where the spec uses regex patterns that require engines
 // like ECMAScript or RE2.
@@ -80,9 +87,16 @@ If not specified, the default libopenapi regex engine is "re2"".`)
 //   - Flags:  ignorecase, multiline, explicitcapture, compiled, singleline,
 //     ignorepatternwhitespace, righttoleft, debug, unicode
 //
+// `--yaml2json` flag to convert YAML files to JSON before validation.
+// libopenapi passes map[interface{}]interface{} structures for deeply nested
+// objects or complex mappings, which are not allowed in JSON and cannot be
+// validated by jsonschema. This flag allows pre-converting from YAML to JSON
+// to bypass this limitation of the libopenapi. Default is false.
+//
 // Example usage:
 //
 //	go run main.go --regexengine=ecmascript ./my-api-spec.yaml
+//	go run main.go --yaml2json ./my-api-spec.yaml
 //
 // If validation passes, the tool logs a success message.
 // If the document is invalid or there is a processing error, it logs details and exits non-zero.
@@ -94,13 +108,21 @@ Validates an OpenAPI document using libopenapi-validator.
 
 Options:
   --regexengine string   Specify the regex parsing option to use.
-                         Supported values are: 
+                         Supported values are:
                            Engines: re2 (default), ecmascript
-                           Flags:  ignorecase, multiline, explicitcapture, compiled, 
-                                   singleline, ignorepatternwhitespace, righttoleft, 
+                           Flags:  ignorecase, multiline, explicitcapture, compiled,
+                                   singleline, ignorepatternwhitespace, righttoleft,
                                    debug, unicode
                          If not specified, the default libopenapi option is "re2".
 
+  --yaml2json            Convert YAML files to JSON before validation.
+						 libopenapi passes map[interface{}]interface{}
+                         structures for deeply nested objects or complex mappings, which
+                         are not allowed in JSON and cannot be validated by jsonschema.
+                         This flag allows pre-converting from YAML to JSON to bypass this
+                         limitation of the libopenapi.
+                         (default: false)
+
   -h, --help             Show this help message and exit.
 `)
 	}
@@ -156,6 +178,17 @@ Options:
 		os.Exit(1)
 	}
 
+	if *convertYAMLToJSON {
+		var v interface{}
+		if err := yaml.Unmarshal(data, &v); err == nil {
+			data, err = yaml.YAMLToJSON(data)
+			if err != nil {
+				logger.Error("invalid api spec: error converting yaml to json", slog.Any("error", err))
+				os.Exit(1)
+			}
+		}
+	}
+
 	doc, err := libopenapi.NewDocument(data)
 	if err != nil {
 		logger.Error("error creating new libopenapi document", slog.Any("error", err))

go.mod

@@ -5,6 +5,7 @@ go 1.24.7
 require (
 	github.com/basgys/goxml2json v1.1.1-0.20231018121955-e66ee54ceaad
 	github.com/dlclark/regexp2 v1.11.5
+	github.com/goccy/go-yaml v1.18.0
 	github.com/pb33f/jsonpath v0.1.2
 	github.com/pb33f/libopenapi v0.28.2
 	github.com/santhosh-tekuri/jsonschema/v6 v6.0.2

go.sum

@@ -11,6 +11,8 @@ github.com/davecgh/go-spew v1.1.1 h1:vj9j/u1bqnvCEfJOwUhtlOARqs3+rkHYY13jYWTU97c
 github.com/davecgh/go-spew v1.1.1/go.mod h1:J7Y8YcW2NihsgmVo/mv3lAwl/skON4iLHjSsI+c5H38=
 github.com/dlclark/regexp2 v1.11.5 h1:Q/sSnsKerHeCkc/jSTNq1oCm7KiVgUMZRDUoRu0JQZQ=
 github.com/dlclark/regexp2 v1.11.5/go.mod h1:DHkYz0B9wPfa6wondMfaivmHpzrQ3v9q8cnmRbL6yW8=
+github.com/goccy/go-yaml v1.18.0 h1:8W7wMFS12Pcas7KU+VVkaiCng+kG8QiFeFwzFb+rwuw=
+github.com/goccy/go-yaml v1.18.0/go.mod h1:XBurs7gK8ATbW4ZPGKgcbrY1Br56PdM69F7LkFRi1kA=
 github.com/kr/pretty v0.3.1 h1:flRD4NNwYAUpkphVc1HcthR4KEIFJ65n8Mw5qdRn3LE=
 github.com/kr/pretty v0.3.1/go.mod h1:hoEshYVHaxMs3cyo3Yncou5ZscifuDolrwPKZanG3xk=
 github.com/kr/text v0.2.0 h1:5Nx0Ya0ZqY2ygV366QzturHI13Jq95ApcVaJBhpS+AY=