conversion: conversion for file upload from v2 to v3 and vice versa (#…

…233)

This change enables converting spec for file upload with POST from v2 to v3 and vice versa
according to https://swagger.io/docs/specification/2-0/file-upload/ specification.
Added support for `multipart/form-data`.
Added `in: formData` case for file upload.
Updated unit tests related sections.

openapi2conv/openapi2_conv.go

@@ -121,6 +121,51 @@ func ToV3PathItem(swagger *openapi2.Swagger, pathItem *openapi2.PathItem) (*open
 	return result, nil
 }
 
+func ToV3RequestBodyFormData(parameters []*openapi2.Parameter) *openapi3.RequestBodyRef {
+	if len(parameters) == 0 || parameters[0].In != "formData" {
+		return nil
+	}
+	schema := &openapi3.Schema{
+		Type:       "object",
+		Properties: make(map[string]*openapi3.SchemaRef, len(parameters)),
+	}
+	for _, parameter := range parameters {
+		if parameter.In != "formData" || parameter.Name == "" {
+			continue
+		}
+		format := parameter.Format
+		typ := parameter.Type
+		if parameter.Type == "file" {
+			format = "binary"
+			typ = "string"
+		}
+		pschema := &openapi3.Schema{
+			Description:    parameter.Description,
+			Type:           typ,
+			ExtensionProps: parameter.ExtensionProps,
+			Format:         format,
+			Enum:           parameter.Enum,
+			Min:            parameter.Minimum,
+			Max:            parameter.Maximum,
+			ExclusiveMin:   parameter.ExclusiveMin,
+			ExclusiveMax:   parameter.ExclusiveMax,
+			MinLength:      parameter.MinLength,
+			MaxLength:      parameter.MaxLength,
+			Default:        parameter.Default,
+			Items:          parameter.Items,
+			MinItems:       parameter.MinItems,
+			MaxItems:       parameter.MaxItems,
+		}
+		schemaRef := openapi3.SchemaRef{
+			Value: pschema,
+		}
+		schema.Properties[parameter.Name] = &schemaRef
+	}
+	return &openapi3.RequestBodyRef{
+		Value: openapi3.NewRequestBody().WithFormDataSchema(schema),
+	}
+}
+
 func ToV3Operation(swagger *openapi2.Swagger, pathItem *openapi2.PathItem, operation *openapi2.Operation) (*openapi3.Operation, error) {
 	if operation == nil {
 		return nil, nil
@@ -137,15 +182,21 @@ func ToV3Operation(swagger *openapi2.Swagger, pathItem *openapi2.PathItem, opera
 		resultSecurity := ToV3SecurityRequirements(*v)
 		result.Security = &resultSecurity
 	}
-	for _, parameter := range operation.Parameters {
-		v3Parameter, v3RequestBody, err := ToV3Parameter(parameter)
-		if err != nil {
-			return nil, err
-		}
-		if v3RequestBody != nil {
-			result.RequestBody = v3RequestBody
-		} else if v3Parameter != nil {
-			result.Parameters = append(result.Parameters, v3Parameter)
+
+	requestBodyRef := ToV3RequestBodyFormData(operation.Parameters)
+	if requestBodyRef != nil {
+		result.RequestBody = requestBodyRef
+	} else {
+		for _, parameter := range operation.Parameters {
+			v3Parameter, v3RequestBody, err := ToV3Parameter(parameter)
+			if err != nil {
+				return nil, err
+			}
+			if v3RequestBody != nil {
+				result.RequestBody = v3RequestBody
+			} else if v3Parameter != nil {
+				result.Parameters = append(result.Parameters, v3Parameter)
+			}
 		}
 	}
 	if responses := operation.Responses; responses != nil {
@@ -515,6 +566,42 @@ nameSearch:
 	return ""
 }
 
+func FromV3RequestBodyFormData(requestBodyRef *openapi3.RequestBodyRef) openapi2.Parameters {
+	mediaType := requestBodyRef.Value.GetMediaType("multipart/form-data")
+	if mediaType == nil {
+		return nil
+	}
+	parameters := openapi2.Parameters{}
+	for prop, schemaRef := range mediaType.Schema.Value.Properties {
+		val := schemaRef.Value
+		typ := val.Type
+		if val.Format == "binary" {
+			typ = "file"
+		}
+		parameter := &openapi2.Parameter{
+			Name:           prop,
+			Description:    val.Description,
+			Type:           typ,
+			In:             "formData",
+			ExtensionProps: val.ExtensionProps,
+			Enum:           val.Enum,
+			ExclusiveMin:   val.ExclusiveMin,
+			ExclusiveMax:   val.ExclusiveMax,
+			MinLength:      val.MinLength,
+			MaxLength:      val.MaxLength,
+			Default:        val.Default,
+			Items:          val.Items,
+			MinItems:       val.MinItems,
+			MaxItems:       val.MaxItems,
+			Maximum:        val.Max,
+			Minimum:        val.Min,
+			Pattern:        val.Pattern,
+		}
+		parameters = append(parameters, parameter)
+	}
+	return parameters
+}
+
 func FromV3Operation(swagger *openapi3.Swagger, operation *openapi3.Operation) (*openapi2.Operation, error) {
 	if operation == nil {
 		return nil, nil
@@ -539,11 +626,16 @@ func FromV3Operation(swagger *openapi3.Swagger, operation *openapi3.Operation) (
 		result.Parameters = append(result.Parameters, r)
 	}
 	if v := operation.RequestBody; v != nil {
-		r, err := FromV3RequestBody(swagger, operation, v)
-		if err != nil {
-			return nil, err
+		parameters := FromV3RequestBodyFormData(operation.RequestBody)
+		if len(parameters) > 0 {
+			result.Parameters = append(result.Parameters, parameters...)
+		} else {
+			r, err := FromV3RequestBody(swagger, operation, v)
+			if err != nil {
+				return nil, err
+			}
+			result.Parameters = append(result.Parameters, r)
 		}
-		result.Parameters = append(result.Parameters, r)
 	}
 	if responses := operation.Responses; responses != nil {
 		resultResponses, err := FromV3Responses(responses)

openapi2conv/openapi2_conv_test.go

@@ -161,7 +161,22 @@ const exampleV2 = `
       },
       "post": {
         "description": "example post",
-        "responses": {}
+        "responses": {},
+        "parameters": [
+          {
+            "in": "formData",
+            "name": "fileUpload",
+            "type": "file",
+            "description": "param description",
+            "x-mimetype": "text/plain"
+          },
+          {
+            "in": "formData",
+            "name":"note",
+            "type": "integer",
+            "description": "Description of file contents"
+          }
+        ]
       },
       "put": {
         "description": "example put",
@@ -424,7 +439,28 @@ const exampleV3 = `
       },
       "post": {
         "description": "example post",
-        "responses": {}
+        "responses": {},
+        "requestBody": {
+          "content": {
+            "multipart/form-data": {
+              "schema": {
+                "properties": {
+                  "fileUpload": {
+                    "description": "param description",
+                    "format": "binary",
+                    "type": "string",
+                    "x-mimetype": "text/plain"
+                  },
+                  "note":{
+                    "type": "integer",
+                    "description": "Description of file contents"
+                  }
+                },
+                "type": "object"
+              }
+            }
+          }
+        }
       },
       "put": {
         "description": "example put",

openapi3/content.go

@@ -23,6 +23,18 @@ func NewContentWithJSONSchemaRef(schema *SchemaRef) Content {
 	}
 }
 
+func NewContentWithFormDataSchema(schema *Schema) Content {
+	return Content{
+		"multipart/form-data": NewMediaType().WithSchema(schema),
+	}
+}
+
+func NewContentWithFormDataSchemaRef(schema *SchemaRef) Content {
+	return Content{
+		"multipart/form-data": NewMediaType().WithSchemaRef(schema),
+	}
+}
+
 func (content Content) Get(mime string) *MediaType {
 	// If the mime is empty then short-circuit to the wildcard.
 	// We do this here so that we catch only the specific case of

openapi3/request_body.go

@@ -43,6 +43,16 @@ func (requestBody *RequestBody) WithJSONSchema(value *Schema) *RequestBody {
 	return requestBody
 }
 
+func (requestBody *RequestBody) WithFormDataSchemaRef(value *SchemaRef) *RequestBody {
+	requestBody.Content = NewContentWithFormDataSchemaRef(value)
+	return requestBody
+}
+
+func (requestBody *RequestBody) WithFormDataSchema(value *Schema) *RequestBody {
+	requestBody.Content = NewContentWithFormDataSchema(value)
+	return requestBody
+}
+
 func (requestBody *RequestBody) GetMediaType(mediaType string) *MediaType {
 	m := requestBody.Content
 	if m == nil {