[Vertex AI] Add responseSchema to GenerationConfig (#13576)

Author: andrewheard

FirebaseVertexAI/CHANGELOG.md

@@ -9,6 +9,10 @@
 - [changed] **Breaking Change**: The source image in the
   `ImageConversionError.couldNotConvertToJPEG` error case is now an enum value
   instead of the `Any` type. (#13575)
+- [added] Added support for specifying a JSON `responseSchema` in
+  `GenerationConfig`; see
+  [control generated output](https://cloud.google.com/vertex-ai/generative-ai/docs/multimodal/control-generated-output)
+  for more details. (#13576)
 
 # 10.29.0
 - [feature] Added community support for watchOS. (#13215)

FirebaseVertexAI/Sources/GenerationConfig.swift

@@ -70,6 +70,17 @@ public struct GenerationConfig {
   /// - `application/json`: JSON response in the candidates.
   public let responseMIMEType: String?
 
+  /// Output schema of the generated candidate text.
+  /// If set, a compatible ``responseMIMEType`` must also be set.
+  ///
+  /// Compatible MIME types:
+  ///   - `application/json`: Schema for JSON response.
+  ///
+  /// Refer to the [Control generated
+  /// output](https://cloud.google.com/vertex-ai/generative-ai/docs/multimodal/control-generated-output)
+  /// guide for more details.
+  public let responseSchema: Schema?
+
   /// Creates a new `GenerationConfig` value.
   ///
   /// - Parameter temperature: See ``temperature``
@@ -78,9 +89,12 @@ public struct GenerationConfig {
   /// - Parameter candidateCount: See ``candidateCount``
   /// - Parameter maxOutputTokens: See ``maxOutputTokens``
   /// - Parameter stopSequences: See ``stopSequences``
+  /// - Parameter responseMIMEType: See ``responseMIMEType``
+  /// - Parameter responseSchema: See ``responseSchema``
   public init(temperature: Float? = nil, topP: Float? = nil, topK: Int? = nil,
               candidateCount: Int? = nil, maxOutputTokens: Int? = nil,
-              stopSequences: [String]? = nil, responseMIMEType: String? = nil) {
+              stopSequences: [String]? = nil, responseMIMEType: String? = nil,
+              responseSchema: Schema? = nil) {
     // Explicit init because otherwise if we re-arrange the above variables it changes the API
     // surface.
     self.temperature = temperature
@@ -90,6 +104,7 @@ public struct GenerationConfig {
     self.maxOutputTokens = maxOutputTokens
     self.stopSequences = stopSequences
     self.responseMIMEType = responseMIMEType
+    self.responseSchema = responseSchema
   }
 }
 

FirebaseVertexAI/Tests/Unit/GenerationConfigTests.swift

@@ -48,15 +48,16 @@ final class GenerationConfigTests: XCTestCase {
     let candidateCount = 2
     let maxOutputTokens = 256
     let stopSequences = ["END", "DONE"]
-    let responseMIMEType = "text/plain"
+    let responseMIMEType = "application/json"
     let generationConfig = GenerationConfig(
       temperature: temperature,
       topP: topP,
       topK: topK,
       candidateCount: candidateCount,
       maxOutputTokens: maxOutputTokens,
       stopSequences: stopSequences,
-      responseMIMEType: responseMIMEType
+      responseMIMEType: responseMIMEType,
+      responseSchema: Schema(type: .array, items: Schema(type: .string))
     )
 
     let jsonData = try encoder.encode(generationConfig)
@@ -67,6 +68,12 @@ final class GenerationConfigTests: XCTestCase {
       "candidateCount" : \(candidateCount),
       "maxOutputTokens" : \(maxOutputTokens),
       "responseMIMEType" : "\(responseMIMEType)",
+      "responseSchema" : {
+        "items" : {
+          "type" : "STRING"
+        },
+        "type" : "ARRAY"
+      },
       "stopSequences" : [
         "END",
         "DONE"
@@ -78,16 +85,46 @@ final class GenerationConfigTests: XCTestCase {
     """)
   }
 
-  func testEncodeGenerationConfig_responseMIMEType() throws {
-    let mimeType = "image/jpeg"
-    let generationConfig = GenerationConfig(responseMIMEType: mimeType)
+  func testEncodeGenerationConfig_jsonResponse() throws {
+    let mimeType = "application/json"
+    let generationConfig = GenerationConfig(
+      responseMIMEType: mimeType,
+      responseSchema: Schema(
+        type: .object,
+        properties: [
+          "firstName": Schema(type: .string),
+          "lastName": Schema(type: .string),
+          "age": Schema(type: .integer),
+        ],
+        requiredProperties: ["firstName", "lastName", "age"]
+      )
+    )
 
     let jsonData = try encoder.encode(generationConfig)
 
     let json = try XCTUnwrap(String(data: jsonData, encoding: .utf8))
     XCTAssertEqual(json, """
     {
-      "responseMIMEType" : "\(mimeType)"
+      "responseMIMEType" : "\(mimeType)",
+      "responseSchema" : {
+        "properties" : {
+          "age" : {
+            "type" : "INTEGER"
+          },
+          "firstName" : {
+            "type" : "STRING"
+          },
+          "lastName" : {
+            "type" : "STRING"
+          }
+        },
+        "required" : [
+          "firstName",
+          "lastName",
+          "age"
+        ],
+        "type" : "OBJECT"
+      }
     }
     """)
   }