fix: non-nullable schema receiving null input does not coerce for default types on object and arrays (#670)

Author: rhighs

README.md

@@ -590,6 +590,8 @@ Otherwise, instead of raising an error, null values will be coerced as follows:
 - `number` -> `0`
 - `string` -> `""`
 - `boolean` -> `false`
+- `object` -> `{}`
+- `array` -> `[]`
 
 <a name="largearrays"></a>
 #### Large Arrays

index.js

@@ -560,10 +560,13 @@ function buildObject (context, location) {
   let functionCode = `
   `
 
+  const nullable = schema.nullable === true
   functionCode += `
     // ${schemaRef}
     function ${functionName} (input) {
       const obj = ${toJSON('input')}
+      ${!nullable ? 'if (obj === null) return \'{}\'' : ''}
+
       ${buildInnerObject(context, location)}
     }
   `
@@ -601,7 +604,9 @@ function buildArray (context, location) {
       // ${schemaRef}
   `
 
+  const nullable = schema.nullable === true
   functionCode += `
+    ${!nullable ? 'if (obj === null) return \'[]\'' : ''}
     if (!Array.isArray(obj)) {
       throw new TypeError(\`The value of '${schemaRef}' does not match schema definition.\`)
     }

test/toJSON.test.js

@@ -127,7 +127,7 @@ test('not fail on null sub-object declared nullable', (t) => {
   t.equal('{"product":null}', stringify(object))
 })
 
-test('throw an error on non nullable null sub-object', (t) => {
+test('on non nullable null sub-object it should coerce to {}', (t) => {
   t.plan(1)
 
   const stringify = build({
@@ -148,10 +148,12 @@ test('throw an error on non nullable null sub-object', (t) => {
   const object = {
     product: null
   }
-  t.throws(() => { stringify(object) })
+
+  const result = stringify(object)
+  t.equal(result, JSON.stringify({ product: {} }))
 })
 
-test('throw an error on non nullable null object', (t) => {
+test('on non nullable null object it should coerce to {}', (t) => {
   t.plan(1)
 
   const stringify = build({
@@ -170,5 +172,32 @@ test('throw an error on non nullable null object', (t) => {
       }
     }
   })
-  t.throws(() => { stringify(null) })
+
+  const result = stringify(null)
+  t.equal(result, '{}')
+})
+
+test('on non-nullable null object it should skip rendering, skipping required fields checks', (t) => {
+  t.plan(1)
+
+  const stringify = build({
+    title: 'simple object',
+    nullable: false,
+    type: 'object',
+    properties: {
+      product: {
+        nullable: false,
+        type: 'object',
+        properties: {
+          name: {
+            type: 'string'
+          }
+        }
+      }
+    },
+    required: ['product']
+  })
+
+  const result = stringify(null)
+  t.equal(result, '{}')
 })

test/typesArray.test.js

@@ -467,7 +467,7 @@ test('class instance that is simultaneously a string and a json', (t) => {
   t.equal(valueObj, '{"simultaneously":{"foo":"hello"}}')
 })
 
-test('should throw an error when type is array and object is null', (t) => {
+test('should not throw an error when type is array and object is null, it should instead coerce to []', (t) => {
   t.plan(1)
   const schema = {
     type: 'object',
@@ -482,7 +482,8 @@ test('should throw an error when type is array and object is null', (t) => {
   }
 
   const stringify = build(schema)
-  t.throws(() => stringify({ arr: null }), new TypeError('The value of \'#/properties/arr\' does not match schema definition.'))
+  const result = stringify({ arr: null })
+  t.equal(result, JSON.stringify({ arr: [] }))
 })
 
 test('should throw an error when type is array and object is not an array', (t) => {