fix: sample schema should stringify string values for content-type: text/json (#6431)

* reverts #6412 which stringified string value if content-type: text/plain 
* enable stringify string values matching `/json/` and allowList of `shouldStringifyTypes` ("string")

src/core/utils.js

@@ -541,8 +541,7 @@ export const validateParam = (param, value, { isOAS3 = false, bypassRequiredChec
   return errors
 }
 
-export const getSampleSchema = (schema, contentType="", config={}) => {
+const getXmlSampleSchema = (schema, config) => {
-  if (/xml/.test(contentType)) {
   if (!schema.xml || !schema.xml.name) {
     schema.xml = schema.xml || {}
 
@@ -556,15 +555,40 @@ export const getSampleSchema = (schema, contentType="", config={}) => {
     }
   }
   return memoizedCreateXMLExample(schema, config)
+}
+
+const shouldStringifyTypesConfig = [
+  {
+    when: /json/,
+    shouldStringifyTypes: ["string"]
   }
+]
 
+const defaultStringifyTypes = ["object"]
+
+const getStringifiedSampleForSchema = (schema, config, contentType) => {
   const res = memoizedSampleFromSchema(schema, config)
+  const resType = typeof res
 
-  return typeof res === "object" || typeof res === "string" 
+  const typesToStringify = shouldStringifyTypesConfig.reduce(
+    (types, nextConfig) => nextConfig.when.test(contentType)
+      ? [...types, ...nextConfig.shouldStringifyTypes]
+      : types,
+    defaultStringifyTypes)
+
+  return some(typesToStringify, x => x === resType)
     ? JSON.stringify(res, null, 2)
     : res
 }
 
+export const getSampleSchema = (schema, contentType="", config={}) => {
+  if (/xml/.test(contentType)) {
+    return getXmlSampleSchema(schema, config)
+  }
+
+  return getStringifiedSampleForSchema(schema, config, contentType)
+}
+
 export const parseSearch = () => {
   let map = {}
   let search = win.location.search

test/unit/core/utils.js

@@ -1494,7 +1494,18 @@ describe("utils", () => {
       Date = oriDate
     })
     
-    it("should stringify string values", () => {
+    it("should stringify string values if json content-type", () => {
+      // Given
+      const res = getSampleSchema({
+        type: "string",
+        format: "date-time"
+      }, "text/json")
+      
+      // Then
+      expect(res).toEqual(JSON.stringify(new Date().toISOString()))
+    })
+
+    it("should not unnecessarily stringify string values for other content-types", () => {
       // Given
       const res = getSampleSchema({
         type: "string",
@@ -1502,7 +1513,7 @@ describe("utils", () => {
       })
       
       // Then
-      expect(res).toEqual(JSON.stringify(new Date().toISOString()))
+      expect(res).toEqual(new Date().toISOString())
     })
 
     it("should not unnecessarily stringify non-object values", () => {
@@ -1514,6 +1525,16 @@ describe("utils", () => {
       // Then
       expect(res).toEqual(0)
     })
+
+    it("should not unnecessarily stringify non-object values if content-type is json", () => {
+      // Given
+      const res = getSampleSchema({
+        type: "number"
+      }, "application/json")
+      
+      // Then
+      expect(res).toEqual(0)
+    })
   })
   
   describe("paramToIdentifier", () => {