fix: type erasure breaking nested generics (#285)

CHANGELOG.md

@@ -6,6 +6,7 @@
 
 ### Changed
 - Can now put redoc route behind authentication
+- Fixed issue where type erasure was breaking nested generics
 
 ### Remove
 

core/src/test/kotlin/io/bkbn/kompendium/core/KompendiumTest.kt

@@ -16,6 +16,8 @@ import io.bkbn.kompendium.core.util.TestModules.genericPolymorphicResponse
 import io.bkbn.kompendium.core.util.TestModules.genericPolymorphicResponseMultipleImpls
 import io.bkbn.kompendium.core.util.TestModules.headerParameter
 import io.bkbn.kompendium.core.util.TestModules.multipleExceptions
+import io.bkbn.kompendium.core.util.TestModules.nestedGenericCollection
+import io.bkbn.kompendium.core.util.TestModules.nestedGenericMultipleParamsCollection
 import io.bkbn.kompendium.core.util.TestModules.nestedGenericResponse
 import io.bkbn.kompendium.core.util.TestModules.nonRequiredParam
 import io.bkbn.kompendium.core.util.TestModules.polymorphicException
@@ -157,6 +159,12 @@ class KompendiumTest : DescribeSpec({
     it("Can handle an absolutely psycho inheritance test") {
       openApiTestAllSerializers("T0033__crazy_polymorphic_example.json") { genericPolymorphicResponseMultipleImpls() }
     }
+    it("Can support nested generic collections") {
+      openApiTestAllSerializers("T0039__nested_generic_collection.json") { nestedGenericCollection() }
+    }
+    it("Can support nested generics with multiple type parameters") {
+      openApiTestAllSerializers("T0040__nested_generic_multiple_type_params.json") { nestedGenericMultipleParamsCollection() }
+    }
   }
   describe("Miscellaneous") {
     xit("Can generate the necessary ReDoc home page") {

core/src/test/kotlin/io/bkbn/kompendium/core/util/TestModules.kt

@@ -8,8 +8,10 @@ import io.bkbn.kompendium.core.fixtures.ExceptionResponse
 import io.bkbn.kompendium.core.fixtures.Flibbity
 import io.bkbn.kompendium.core.fixtures.FlibbityGibbit
 import io.bkbn.kompendium.core.fixtures.Gibbity
+import io.bkbn.kompendium.core.fixtures.MultiNestedGenerics
 import io.bkbn.kompendium.core.fixtures.NullableEnum
 import io.bkbn.kompendium.core.fixtures.NullableField
+import io.bkbn.kompendium.core.fixtures.Page
 import io.bkbn.kompendium.core.fixtures.ProfileUpdateRequest
 import io.bkbn.kompendium.core.fixtures.TestCreatedResponse
 import io.bkbn.kompendium.core.fixtures.TestNested
@@ -567,6 +569,10 @@ object TestModules {
 
   fun Routing.genericPolymorphicResponseMultipleImpls() = basicGetGenerator<Flibbity<FlibbityGibbit>>()
 
+  fun Routing.nestedGenericCollection() = basicGetGenerator<Page<Int>>()
+
+  fun Routing.nestedGenericMultipleParamsCollection() = basicGetGenerator<MultiNestedGenerics<String, ComplexRequest>>()
+
   fun Routing.withOperationId() = basicGetGenerator<TestResponse>(operationId = "getThisDude")
 
   fun Routing.nullableNestedObject() = basicGetGenerator<ProfileUpdateRequest>()
@@ -575,14 +581,16 @@ object TestModules {
 
   fun Routing.dateTimeString() = basicGetGenerator<DateTimeString>()
 
-  fun Routing.headerParameter() = basicGetGenerator<TestResponse>( params = listOf(
+  fun Routing.headerParameter() = basicGetGenerator<TestResponse>(
+    params = listOf(
       Parameter(
         name = "X-User-Email",
         `in` = Parameter.Location.header,
         schema = TypeDefinition.STRING,
         required = true
       )
-  ))
+    )
+  )
 
   fun Routing.simpleRecursive() = basicGetGenerator<ColumnSchema>()
 

core/src/test/resources/T0039__nested_generic_collection.json

@@ -0,0 +1,101 @@
+{
+  "openapi": "3.1.0",
+  "jsonSchemaDialect": "https://json-schema.org/draft/2020-12/schema",
+  "info": {
+    "title": "Test API",
+    "version": "1.33.7",
+    "description": "An amazing, fully-ish 😉 generated API spec",
+    "termsOfService": "https://example.com",
+    "contact": {
+      "name": "Homer Simpson",
+      "url": "https://gph.is/1NPUDiM",
+      "email": "chunkylover53@aol.com"
+    },
+    "license": {
+      "name": "MIT",
+      "url": "https://github.com/bkbnio/kompendium/blob/main/LICENSE"
+    }
+  },
+  "servers": [
+    {
+      "url": "https://myawesomeapi.com",
+      "description": "Production instance of my API"
+    },
+    {
+      "url": "https://staging.myawesomeapi.com",
+      "description": "Where the fun stuff happens"
+    }
+  ],
+  "paths": {
+    "/": {
+      "get": {
+        "tags": [],
+        "summary": "Great Summary!",
+        "description": "testing more",
+        "parameters": [],
+        "responses": {
+          "200": {
+            "description": "A Successful Endeavor",
+            "content": {
+              "application/json": {
+                "schema": {
+                  "$ref": "#/components/schemas/Page-Int"
+                }
+              }
+            }
+          }
+        },
+        "deprecated": false
+      },
+      "parameters": []
+    }
+  },
+  "webhooks": {},
+  "components": {
+    "schemas": {
+      "Page-Int": {
+        "type": "object",
+        "properties": {
+          "content": {
+            "items": {
+              "type": "number",
+              "format": "int32"
+            },
+            "type": "array"
+          },
+          "number": {
+            "type": "number",
+            "format": "int32"
+          },
+          "numberOfElements": {
+            "type": "number",
+            "format": "int32"
+          },
+          "size": {
+            "type": "number",
+            "format": "int32"
+          },
+          "totalElements": {
+            "type": "number",
+            "format": "int64"
+          },
+          "totalPages": {
+            "type": "number",
+            "format": "int32"
+          }
+        },
+        "required": [
+          "content",
+          "number",
+          "numberOfElements",
+          "size",
+          "totalElements",
+          "totalPages"
+        ]
+      }
+    },
+    "securitySchemes": {}
+  },
+  "security": [],
+  "tags": []
+}

core/src/test/resources/T0040__nested_generic_multiple_type_params.json

@@ -0,0 +1,129 @@
+{
+  "openapi": "3.1.0",
+  "jsonSchemaDialect": "https://json-schema.org/draft/2020-12/schema",
+  "info": {
+    "title": "Test API",
+    "version": "1.33.7",
+    "description": "An amazing, fully-ish 😉 generated API spec",
+    "termsOfService": "https://example.com",
+    "contact": {
+      "name": "Homer Simpson",
+      "url": "https://gph.is/1NPUDiM",
+      "email": "chunkylover53@aol.com"
+    },
+    "license": {
+      "name": "MIT",
+      "url": "https://github.com/bkbnio/kompendium/blob/main/LICENSE"
+    }
+  },
+  "servers": [
+    {
+      "url": "https://myawesomeapi.com",
+      "description": "Production instance of my API"
+    },
+    {
+      "url": "https://staging.myawesomeapi.com",
+      "description": "Where the fun stuff happens"
+    }
+  ],
+  "paths": {
+    "/": {
+      "get": {
+        "tags": [],
+        "summary": "Great Summary!",
+        "description": "testing more",
+        "parameters": [],
+        "responses": {
+          "200": {
+            "description": "A Successful Endeavor",
+            "content": {
+              "application/json": {
+                "schema": {
+                  "$ref": "#/components/schemas/MultiNestedGenerics-String-ComplexRequest"
+                }
+              }
+            }
+          }
+        },
+        "deprecated": false
+      },
+      "parameters": []
+    }
+  },
+  "webhooks": {},
+  "components": {
+    "schemas": {
+      "CrazyItem": {
+        "type": "object",
+        "properties": {
+          "enumeration": {
+            "enum": [
+              "ONE",
+              "TWO"
+            ]
+          }
+        },
+        "required": [
+          "enumeration"
+        ]
+      },
+      "NestedComplexItem": {
+        "type": "object",
+        "properties": {
+          "alias": {
+            "additionalProperties": {
+              "$ref": "#/components/schemas/CrazyItem"
+            },
+            "type": "object"
+          },
+          "name": {
+            "type": "string"
+          }
+        },
+        "required": [
+          "alias",
+          "name"
+        ]
+      },
+      "ComplexRequest": {
+        "type": "object",
+        "properties": {
+          "amazingField": {
+            "type": "string"
+          },
+          "org": {
+            "type": "string"
+          },
+          "tables": {
+            "items": {
+              "$ref": "#/components/schemas/NestedComplexItem"
+            },
+            "type": "array"
+          }
+        },
+        "required": [
+          "amazingField",
+          "org",
+          "tables"
+        ]
+      },
+      "MultiNestedGenerics-String-ComplexRequest": {
+        "type": "object",
+        "properties": {
+          "content": {
+            "additionalProperties": {
+              "$ref": "#/components/schemas/ComplexRequest"
+            },
+            "type": "object"
+          }
+        },
+        "required": [
+          "content"
+        ]
+      }
+    },
+    "securitySchemes": {}
+  },
+  "security": [],
+  "tags": []
+}

core/src/testFixtures/kotlin/io/bkbn/kompendium/core/fixtures/TestModels.kt

@@ -118,3 +118,16 @@ public data class ProfileMetadataUpdateRequest(
   public val isPrivate: Boolean?,
   public val otherThing: String?
 )
+
+data class Page<T>(
+  val content: List<T>,
+  val totalElements: Long,
+  val totalPages: Int,
+  val numberOfElements: Int,
+  val number: Int,
+  val size: Int
+)
+
+data class MultiNestedGenerics<T, E>(
+  val content: Map<T, E>
+)

json-schema/src/main/kotlin/io/bkbn/kompendium/json/schema/handler/SimpleObjectHandler.kt

@@ -13,6 +13,7 @@ import kotlin.reflect.KProperty
 import kotlin.reflect.KType
 import kotlin.reflect.KTypeParameter
 import kotlin.reflect.KTypeProjection
+import kotlin.reflect.full.createType
 import kotlin.reflect.full.memberProperties
 import kotlin.reflect.full.primaryConstructor
 
@@ -22,10 +23,13 @@ object SimpleObjectHandler {
     // cache[type.getSimpleSlug()] = ReferenceDefinition("RECURSION_PLACEHOLDER")
     val typeMap = clazz.typeParameters.zip(type.arguments).toMap()
     val props = clazz.memberProperties.associate { prop ->
-      val schema = when (typeMap.containsKey(prop.returnType.classifier)) {
+      val schema = when (prop.needsToInjectGenerics(typeMap)) {
+        true -> handleNestedGenerics(typeMap, prop, cache)
+        false -> when (typeMap.containsKey(prop.returnType.classifier)) {
           true -> handleGenericProperty(prop, typeMap, cache)
           false -> handleProperty(prop, cache)
         }
+      }
 
       prop.name to schema
     }
@@ -48,6 +52,34 @@ object SimpleObjectHandler {
     }
   }
 
+  private fun KProperty<*>.needsToInjectGenerics(
+    typeMap: Map<KTypeParameter, KTypeProjection>
+  ): Boolean {
+    val typeSymbols = returnType.arguments.map { it.type.toString() }
+    return typeMap.any { (k, _) -> typeSymbols.contains(k.name) }
+  }
+
+  private fun handleNestedGenerics(
+    typeMap: Map<KTypeParameter, KTypeProjection>,
+    prop: KProperty<*>,
+    cache: MutableMap<String, JsonSchema>
+  ): JsonSchema {
+    val propClass = prop.returnType.classifier as KClass<*>
+    val types = prop.returnType.arguments.map {
+      val typeSymbol = it.type.toString()
+      typeMap.filterKeys { k -> k.name == typeSymbol }.values.first()
+    }
+    val constructedType = propClass.createType(types)
+    return SchemaGenerator.fromTypeToSchema(constructedType, cache).let {
+      if (it is TypeDefinition && it.type == "object") {
+        cache[constructedType.getSimpleSlug()] = it
+        ReferenceDefinition(prop.returnType.getReferenceSlug())
+      } else {
+        it
+      }
+    }
+  }
+
   private fun handleGenericProperty(
     prop: KProperty<*>,
     typeMap: Map<KTypeParameter, KTypeProjection>,