Feat : apply optional is nullable (#245)

* feat: apply optional is nullable

* chore: refactoring

* chore: remove needless

* fix deprecated

* fix for test

Author: xeromank

restdocs-api-spec-jsonschema/src/main/kotlin/com/epages/restdocs/apispec/jsonschema/JsonSchemaFromFieldDescriptorsGenerator.kt

@@ -15,6 +15,7 @@ import com.fasterxml.jackson.module.kotlin.jacksonObjectMapper
 import org.everit.json.schema.ArraySchema
 import org.everit.json.schema.BooleanSchema
 import org.everit.json.schema.CombinedSchema
+import org.everit.json.schema.CombinedSchema.oneOf
 import org.everit.json.schema.EmptySchema
 import org.everit.json.schema.EnumSchema
 import org.everit.json.schema.NullSchema
@@ -206,9 +207,26 @@ class JsonSchemaFromFieldDescriptorsGenerator {
     ) : FieldDescriptor(path, description, type, optional, ignored, attributes) {
 
         fun jsonSchemaType(): Schema {
-            val schemaBuilders = jsonSchemaPrimitiveTypes.map { typeToSchema(it) }
-            return if (schemaBuilders.size == 1) schemaBuilders.first().description(description).build()
-            else CombinedSchema.oneOf(schemaBuilders.map { it.build() }).description(description).build()
+            val schemaBuilders: List<Schema.Builder<*>>
+            if (jsonSchemaPrimitiveTypes.size > 1 &&
+                optional &&
+                !jsonSchemaPrimitiveTypes.contains("null")
+            ) {
+                schemaBuilders = jsonSchemaPrimitiveTypes
+                    .plus(jsonSchemaPrimitiveTypeFromDescriptorType("null"))
+                    .map { typeToSchema(it) }
+            } else {
+                schemaBuilders = jsonSchemaPrimitiveTypes.map { typeToSchema(it) }
+            }
+            return if (schemaBuilders.size == 1) schemaBuilders.first().description(description).checkNullable().build()
+            else oneOf(schemaBuilders.map { it.build() }).description(description).checkNullable().build()
+        }
+
+        private fun Schema.Builder<out Schema>.checkNullable(): Schema.Builder<out Schema> {
+            if (optional) {
+                this.nullable(true)
+            }
+            return this
         }
 
         fun merge(fieldDescriptor: FieldDescriptor): FieldDescriptorWithSchemaType {
@@ -230,7 +248,9 @@ class JsonSchemaFromFieldDescriptorsGenerator {
 
         private fun typeToSchema(type: String): Schema.Builder<*> =
             when (type) {
-                "null" -> NullSchema.builder()
+                "null" -> {
+                    NullSchema.builder().nullable()
+                }
                 "empty" -> EmptySchema.builder()
                 "object" -> ObjectSchema.builder()
                 "array" -> ArraySchema.builder().applyConstraints(this).allItemSchema(arrayItemsSchema())
@@ -246,9 +266,14 @@ class JsonSchemaFromFieldDescriptorsGenerator {
                 else -> throw IllegalArgumentException("unknown field type $type")
             }
 
+        private fun NullSchema.Builder.nullable(): NullSchema.Builder {
+            this.nullable(true)
+            return this
+        }
+
         private fun arrayItemsSchema(): Schema {
             return attributes.itemsType
-                ?.let { typeToSchema(it.toLowerCase()).build() }
+                ?.let { typeToSchema(it.lowercase()).build() }
                 ?: CombinedSchema.oneOf(
                     listOf(
                         ObjectSchema.builder().build(),
@@ -277,7 +302,7 @@ class JsonSchemaFromFieldDescriptorsGenerator {
                 )
 
             private fun jsonSchemaPrimitiveTypeFromDescriptorType(fieldDescriptorType: String) =
-                fieldDescriptorType.toLowerCase()
+                fieldDescriptorType.lowercase()
                     .let { if (it == "varies") "empty" else it } // varies is used by spring rest docs if the type is ambiguous - in json schema we want to represent as empty
         }
     }

restdocs-api-spec-jsonschema/src/test/kotlin/com/epages/restdocs/apispec/jsonschema/JsonSchemaFromFieldDescriptorsGeneratorTest.kt

@@ -19,6 +19,7 @@ import org.everit.json.schema.Schema
 import org.everit.json.schema.StringSchema
 import org.everit.json.schema.ValidationException
 import org.everit.json.schema.loader.SchemaLoader
+import org.everit.json.schema.loader.internal.DefaultSchemaClient
 import org.json.JSONArray
 import org.json.JSONObject
 import org.junit.jupiter.api.Test
@@ -61,6 +62,7 @@ class JsonSchemaFromFieldDescriptorsGeneratorTest {
         val shippingAddressSchema = objectSchema.propertySchemas["shippingAddress"]!!
         then(shippingAddressSchema).isInstanceOf(ObjectSchema::class.java)
         then(shippingAddressSchema.description).isNotEmpty()
+        then(shippingAddressSchema.isNullable).isTrue()
 
         then(objectSchema.definesProperty("billingAddress")).isTrue()
         val billingAddressSchema = objectSchema.propertySchemas["billingAddress"] as ObjectSchema
@@ -120,6 +122,7 @@ class JsonSchemaFromFieldDescriptorsGeneratorTest {
         then(pagePositiveSchema.minimum.toInt()).isEqualTo(1)
         then(pagePositiveSchema.maximum).isNull()
         then(pagePositiveSchema.requiresInteger()).isTrue
+        then(pagePositiveSchema.isNullable).isTrue()
 
         then(objectSchema.definesProperty("page100_200")).isTrue
         then(objectSchema.propertySchemas["page100_200"]).isInstanceOf(NumberSchema::class.java)
@@ -445,7 +448,14 @@ class JsonSchemaFromFieldDescriptorsGeneratorTest {
     private fun whenSchemaGenerated() {
         schemaString = generator.generateSchema(fieldDescriptors!!)
         println(schemaString)
-        schema = SchemaLoader.load(JSONObject(schemaString))
+        schema = SchemaLoader
+            .builder()
+            .nullableSupport(true)
+            .schemaJson(JSONObject(schemaString))
+            .schemaClient(DefaultSchemaClient())
+            .build()
+            .load()
+            .build()
     }
 
     private fun givenFieldDescriptorWithPrimitiveArray() {
@@ -589,9 +599,9 @@ class JsonSchemaFromFieldDescriptorsGeneratorTest {
 
     private fun givenDifferentFieldDescriptorsWithSamePathAndDifferentTypes() {
         fieldDescriptors = listOf(
-            FieldDescriptor("id", "some", "STRING"),
-            FieldDescriptor("id", "some", "NULL"),
-            FieldDescriptor("id", "some", "BOOLEAN")
+            FieldDescriptor("id", "some", "STRING", true),
+            FieldDescriptor("id", "some", "NULL", true),
+            FieldDescriptor("id", "some", "BOOLEAN", true)
         )
     }