#26 Implement ExtraTypesHandler which enables adding custom types support by clients

README.md

@@ -159,96 +159,157 @@ class ExampleController @Autowired()(openAPIModelRegistration: OpenAPIModelRegis
 }
 ```
 
+### Adding support for custom types
+To add support for custom types (or overwrite handling of any type supported by the library) 
+one can create a custom `ExtraTypesHandler` and provide it when creating a `Bundle`.
+
+There are multiple ways to do so, the simplest is to use `ExtraTypesHandling.simpleMapping`, for example:
+```scala
+OpenAPIModelRegistration.ExtraTypesHandling.simpleMapping {
+  case t if t =:= typeOf[JsValue] =>
+    val schema = new Schema
+    schema.setType("string")
+    schema.setFormat("json")
+    schema
+}
+```
+This `ExtraTypesHandler` handles `JsValue` by mapping it to simple OpenAPI `string` type with `json` format.
+
+But `ExtraTypesHandler` can also be much more powerful, for example: 
+```scala
+case class CustomClassComplexChild(a: Option[Int])
+
+class CustomClass(val complexChild: CustomClassComplexChild) {
+  // these won't be included
+  val meaningOfLife: Int = 42
+  val alphabetHead: String = "abc"
+}
+
+...
+
+val extraTypesHandler: ExtraTypesHandler = (tpe: Type) =>
+  tpe match {
+    case t if t =:= typeOf[CustomClass] =>
+      val childTypesToBeResolvedByTheLibrary = Set(typeOf[CustomClassComplexChild])
+
+      val handleFn: HandleFn = (resolvedChildTypes, context) => {
+        val name = "CustomClass"
+        val customClassComplexChildResolvedSchema = resolvedChildTypes(typeOf[CustomClassComplexChild])
+        val schema = new Schema
+        schema.addProperty("complexChild", customClassComplexChildResolvedSchema)
+        context.components.addSchemas(name, schema)
+        val schemaReference = new Schema
+        schemaReference.set$ref(s"#/components/schemas/$name")
+        schemaReference
+      }
+
+      (childTypesToBeResolvedByTheLibrary, handleFn)
+  }
+```
+This `ExtraTypesHandler` handles `CustomClass`. 
+`CustomClass` uses `CustomClassComplexChild`, 
+so the handler requests the library to resolve its type (`childTypesToBeResolvedByTheLibrary`).
+This resolved type is available as input to `HandleFn`.
+Then, in `handleFn`, the handler creates a `Schema` object for `CustomClass`, 
+adds it to `Components` so that it can be referenced by name `CustomClass`,
+and returns reference to that object.
+
+
 ## Examples
 
 ### Simple example for springdoc-openapi-scala-1
 Can be found in this repo: [link](examples/springdoc-openapi-scala-1/simple). It generates the following OpenAPI JSON doc:
 ```json
 {
-    "openapi": "3.0.1",
-    "info": {
-        "title": "Example API with springdoc-openapi v1.x",
-        "version": "1.0.0"
-    },
-    "servers": [
-        {
-            "url": "http://localhost:8080",
-            "description": "Generated server url"
-        }
-    ],
-    "paths": {
-        "/api/v1/example/some-endpoint": {
-            "post": {
-                "tags": [
-                    "example-controller"
-                ],
-                "operationId": "someEndpoint",
-                "requestBody": {
-                    "content": {
-                        "application/json": {
-                            "schema": {
-                                "$ref": "#/components/schemas/ExampleModelRequest"
-                            }
-                        }
-                    },
-                    "required": true
-                },
-                "responses": {
-                    "200": {
-                        "description": "OK",
-                        "content": {
-                            "application/json": {
-                                "schema": {
-                                    "$ref": "#/components/schemas/ExampleModelResponse"
-                                }
-                            }
-                        }
-                    }
+  "openapi": "3.0.1",
+  "info": {
+    "title": "Example API with springdoc-openapi v1.x",
+    "version": "1.0.0"
+  },
+  "servers": [
+    {
+      "url": "http://localhost:8080",
+      "description": "Generated server url"
+    }
+  ],
+  "paths": {
+    "/api/v1/example/some-endpoint": {
+      "post": {
+        "tags": [
+          "example-controller"
+        ],
+        "operationId": "someEndpoint",
+        "requestBody": {
+          "content": {
+            "application/json": {
+              "schema": {
+                "$ref": "#/components/schemas/ExampleModelRequest"
+              }
+            }
+          },
+          "required": true
+        },
+        "responses": {
+          "200": {
+            "description": "OK",
+            "content": {
+              "application/json": {
+                "schema": {
+                  "$ref": "#/components/schemas/ExampleModelResponse"
                 }
+              }
             }
+          }
         }
-    },
-    "components": {
-        "schemas": {
-            "ExampleModelRequest": {
-                "required": [
-                    "a",
-                    "b"
-                ],
-                "properties": {
-                    "a": {
-                        "type": "integer",
-                        "format": "int32"
-                    },
-                    "b": {
-                        "type": "string"
-                    },
-                    "c": {
-                        "type": "integer",
-                        "format": "int32"
-                    }
-                }
-            },
-            "ExampleModelResponse": {
-                "required": [
-                    "d",
-                    "e"
-                ],
-                "properties": {
-                    "d": {
-                        "type": "array",
-                        "items": {
-                            "type": "integer",
-                            "format": "int32"
-                        }
-                    },
-                    "e": {
-                        "type": "boolean"
-                    }
-                }
+      }
+    }
+  },
+  "components": {
+    "schemas": {
+      "ExampleModelRequest": {
+        "required": [
+          "a",
+          "b",
+          "d"
+        ],
+        "properties": {
+          "a": {
+            "type": "integer",
+            "format": "int32"
+          },
+          "b": {
+            "type": "string"
+          },
+          "c": {
+            "type": "integer",
+            "format": "int32"
+          },
+          "d": {
+            "type": "string",
+            "format": "json"
+          }
+        }
+      },
+      "ExampleModelResponse": {
+        "required": [
+          "d",
+          "e"
+        ],
+        "properties": {
+          "d": {
+            "type": "array",
+            "items": {
+              "type": "integer",
+              "format": "int32"
             }
+          },
+          "e": {
+            "type": "boolean"
+          }
         }
+      }
     }
+  }
 }
 ```
 
@@ -318,7 +379,8 @@ Can be found in this repo: [link](examples/springdoc-openapi-scala-2/simple). It
         "required": [
           "a",
           "b",
-          "d"
+          "d",
+          "e"
         ],
         "properties": {
           "a": {
@@ -339,6 +401,10 @@ Can be found in this repo: [link](examples/springdoc-openapi-scala-2/simple). It
               "OptionB",
               "OptionA"
             ]
+          },
+          "e": {
+            "type": "string",
+            "format": "json"
           }
         }
       },

examples/springdoc-openapi-scala-1/simple/build.sbt

@@ -23,7 +23,8 @@ lazy val root = (project in file("."))
     libraryDependencies ++= Seq(
       "za.co.absa" %% "springdoc-openapi-scala-1" % `springdoc-openapi-scala-1-version`,
       "org.springdoc" % "springdoc-openapi-webmvc-core" % "1.7.0",
-      "org.springframework.boot" % "spring-boot-starter-web" % "2.6.6"
+      "org.springframework.boot" % "spring-boot-starter-web" % "2.6.6",
+      "com.fasterxml.jackson.core" % "jackson-databind" % "2.16.1"
     ),
     webappWebInfClasses := true,
     inheritJarManifest := true

examples/springdoc-openapi-scala-1/simple/src/main/scala/za/co/absa/springdocopenapiscala/examples/simple/OpenAPIConfiguration.scala

@@ -16,13 +16,16 @@
 
 package za.co.absa.springdocopenapiscala.examples.simple
 
+import com.fasterxml.jackson.databind.JsonNode
 import io.swagger.v3.oas.models.OpenAPI
 import io.swagger.v3.oas.models.info.Info
+import io.swagger.v3.oas.models.media.Schema
 import org.springdoc.core.customizers.OpenApiCustomiser
 import org.springframework.context.annotation.{Bean, Configuration}
-
 import za.co.absa.springdocopenapiscala.{Bundle, OpenAPIModelRegistration}
 
+import scala.reflect.runtime.universe.typeOf
+
 @Configuration
 class OpenAPIConfiguration {
 
@@ -33,7 +36,14 @@ class OpenAPIConfiguration {
           .title("Example API with springdoc-openapi v1.x")
           .version("1.0.0")
       )
-    )
+    ),
+    OpenAPIModelRegistration.ExtraTypesHandling.simpleMapping {
+      case t if t =:= typeOf[JsonNode] =>
+        val schema = new Schema
+        schema.setType("string")
+        schema.setFormat("json")
+        schema
+    }
   )
 
   @Bean

examples/springdoc-openapi-scala-1/simple/src/main/scala/za/co/absa/springdocopenapiscala/examples/simple/model/ExampleModelRequest.scala

@@ -16,4 +16,6 @@
 
 package za.co.absa.springdocopenapiscala.examples.simple.model
 
-case class ExampleModelRequest(a: Int, b: String, c: Option[Int])
+import com.fasterxml.jackson.databind.JsonNode
+
+case class ExampleModelRequest(a: Int, b: String, c: Option[Int], d: JsonNode)

examples/springdoc-openapi-scala-2/simple/build.sbt

@@ -23,7 +23,8 @@ lazy val root = (project in file("."))
     libraryDependencies ++= Seq(
       "za.co.absa" %% "springdoc-openapi-scala-2" % `springdoc-openapi-scala-2-version`,
       "org.springdoc" % "springdoc-openapi-starter-webmvc-api" % "2.3.0",
-      "org.springframework.boot" % "spring-boot-starter-web" % "3.2.0"
+      "org.springframework.boot" % "spring-boot-starter-web" % "3.2.0",
+      "org.playframework" %% "play-json" % "3.0.1"
     ),
     webappWebInfClasses := true,
     inheritJarManifest := true

examples/springdoc-openapi-scala-2/simple/src/main/scala/za/co/absa/springdocopenapiscala/examples/simple/OpenAPIConfiguration.scala

@@ -18,8 +18,12 @@ package za.co.absa.springdocopenapiscala.examples.simple
 
 import io.swagger.v3.oas.models.OpenAPI
 import io.swagger.v3.oas.models.info.Info
+import io.swagger.v3.oas.models.media.Schema
 import org.springdoc.core.customizers.OpenApiCustomizer
 import org.springframework.context.annotation.{Bean, Configuration}
+import play.api.libs.json.JsValue
+
+import scala.reflect.runtime.universe.typeOf
 
 import za.co.absa.springdocopenapiscala.{Bundle, OpenAPIModelRegistration}
 
@@ -33,7 +37,14 @@ class OpenAPIConfiguration {
           .title("Example API with springdoc-openapi v2.x")
           .version("1.0.0")
       )
-    )
+    ),
+    OpenAPIModelRegistration.ExtraTypesHandling.simpleMapping {
+      case t if t =:= typeOf[JsValue] =>
+        val schema = new Schema
+        schema.setType("string")
+        schema.setFormat("json")
+        schema
+    }
   )
 
   @Bean

examples/springdoc-openapi-scala-2/simple/src/main/scala/za/co/absa/springdocopenapiscala/examples/simple/model/ExampleModelRequest.scala

@@ -16,6 +16,8 @@
 
 package za.co.absa.springdocopenapiscala.examples.simple.model
 
+import play.api.libs.json.JsValue
+
 object SimpleEnums extends Enumeration {
 
   type SimpleEnum = Value
@@ -24,4 +26,4 @@ object SimpleEnums extends Enumeration {
 
 }
 
-case class ExampleModelRequest(a: Int, b: String, c: Option[Int], d: SimpleEnums.SimpleEnum)
+case class ExampleModelRequest(a: Int, b: String, c: Option[Int], d: SimpleEnums.SimpleEnum, e: JsValue)

library/src/main/scala/za/co/absa/springdocopenapiscala/Bundle.scala

@@ -17,20 +17,24 @@
 package za.co.absa.springdocopenapiscala
 
 import io.swagger.v3.oas.models.{Components, OpenAPI}
-
+import za.co.absa.springdocopenapiscala.OpenAPIModelRegistration.ExtraTypesHandling
 import za.co.absa.springdocopenapiscala.SpringdocOpenAPIVersionSpecificTypes._
 
 /**
  *  Glues all components of `springdoc-openapi-scala` together
- *  and enables additional customization (for example to set info).
+ *  and enables additional customization (for example to set info or support custom types).
  *
  *  @param extraOpenAPICustomizers additional customizers that are executed after [[OpenAPIScalaCustomizer]]
+ *  @param extraTypesHandler [[ExtraTypesHandling.ExtraTypesHandler]] to be used in model registration
  */
-class Bundle(extraOpenAPICustomizers: Seq[OpenApiCustomizer] = Seq.empty) {
+class Bundle(
+  extraOpenAPICustomizers: Seq[OpenApiCustomizer] = Seq.empty,
+  extraTypesHandler: ExtraTypesHandling.ExtraTypesHandler = ExtraTypesHandling.noExtraHandling
+) {
 
   private val components = new Components
 
-  val modelRegistration: OpenAPIModelRegistration = new OpenAPIModelRegistration(components)
+  val modelRegistration: OpenAPIModelRegistration = new OpenAPIModelRegistration(components, extraTypesHandler)
 
   val customizer: OpenApiCustomizer = {
     val openAPIScalaCustomizer = new OpenAPIScalaCustomizer(components)