feat(chat-models)!: Move all model config options to ChatVertexAIOpti…

…ons (#242)

packages/langchain_google/lib/src/chat_models/models/models.dart

@@ -6,6 +6,8 @@ import 'package:langchain/langchain.dart';
 class ChatVertexAIOptions extends ChatModelOptions {
   /// {@macro chat_vertex_ai_options}
   const ChatVertexAIOptions({
+    this.publisher = 'google',
+    this.model = 'chat-bison',
     this.maxOutputTokens = 1024,
     this.temperature = 0.2,
     this.topP = 0.95,
@@ -15,6 +17,22 @@ class ChatVertexAIOptions extends ChatModelOptions {
     this.examples,
   });
 
+  /// The publisher of the model.
+  ///
+  /// Use `google` for first-party models.
+  final String publisher;
+
+  /// The text model to use.
+  ///
+  /// To use the latest model version, specify the model name without a version
+  /// number (e.g. `chat-bison`).
+  /// To use a stable model version, specify the model version number
+  /// (e.g. `chat-bison@001`).
+  ///
+  /// You can find a list of available models here:
+  /// https://cloud.google.com/vertex-ai/docs/generative-ai/learn/models
+  final String model;
+
   /// Maximum number of tokens that can be generated in the response. A token
   /// is approximately four characters. 100 tokens correspond to roughly
   /// 60-80 words.

packages/langchain_google/lib/src/chat_models/vertex_ai.dart

@@ -116,8 +116,6 @@ class ChatVertexAI extends BaseChatModel<ChatVertexAIOptions> {
     required final String project,
     final String location = 'us-central1',
     final String? rootUrl,
-    this.publisher = 'google',
-    this.model = 'chat-bison',
     this.defaultOptions = const ChatVertexAIOptions(),
   }) : client = VertexAIGenAIClient(
           httpClient: httpClient,
@@ -129,22 +127,6 @@ class ChatVertexAI extends BaseChatModel<ChatVertexAIOptions> {
   /// A client for interacting with Vertex AI API.
   final VertexAIGenAIClient client;
 
-  /// The publisher of the model.
-  ///
-  /// Use `google` for first-party models.
-  final String publisher;
-
-  /// The text model to use.
-  ///
-  /// To use the latest model version, specify the model name without a version
-  /// number (e.g. `chat-bison`).
-  /// To use a stable model version, specify the model version number
-  /// (e.g. `chat-bison@001`).
-  ///
-  /// You can find a list of available models here:
-  /// https://cloud.google.com/vertex-ai/docs/generative-ai/learn/models
-  final String model;
-
   /// The default options to use when calling the model.
   final ChatVertexAIOptions defaultOptions;
 
@@ -181,8 +163,8 @@ class ChatVertexAI extends BaseChatModel<ChatVertexAIOptions> {
       context: context,
       examples: examples,
       messages: vertexMessages,
-      publisher: publisher,
-      model: model,
+      publisher: options?.publisher ?? defaultOptions.publisher,
+      model: options?.model ?? defaultOptions.model,
       parameters: VertexAITextChatModelRequestParams(
         maxOutputTokens:
             options?.maxOutputTokens ?? defaultOptions.maxOutputTokens,
@@ -194,7 +176,7 @@ class ChatVertexAI extends BaseChatModel<ChatVertexAIOptions> {
             options?.candidateCount ?? defaultOptions.candidateCount,
       ),
     );
-    return result.toChatResult(id, model);
+    return result.toChatResult(id, options?.model ?? defaultOptions.model);
   }
 
   /// Tokenizes the given prompt using tiktoken.

packages/langchain_google/test/chat_models/vertex_ai_test.dart

@@ -19,9 +19,9 @@ void main() async {
         project: Platform.environment['VERTEX_AI_PROJECT_ID']!,
         location: 'us-central1',
         rootUrl: 'https://us-central1-aiplatform.googleapis.com/',
-        publisher: 'google',
-        model: 'text-bison@001',
         defaultOptions: const ChatVertexAIOptions(
+          publisher: 'google',
+          model: 'chat-bison@001',
           maxOutputTokens: 10,
           temperature: 0.1,
           topP: 0.1,
@@ -32,11 +32,11 @@ void main() async {
       );
       expect(llm.client.project, Platform.environment['VERTEX_AI_PROJECT_ID']);
       expect(llm.client.location, 'us-central1');
-      expect(llm.publisher, 'google');
-      expect(llm.model, 'text-bison@001');
       expect(
         llm.defaultOptions,
         const ChatVertexAIOptions(
+          publisher: 'google',
+          model: 'chat-bison@001',
           maxOutputTokens: 10,
           temperature: 0.1,
           topP: 0.1,
@@ -83,7 +83,7 @@ void main() async {
         [ChatMessage.humanText('Hello, how are you?')],
       );
       expect(res.modelOutput, isNotNull);
-      expect(res.modelOutput!['model'], chat.model);
+      expect(res.modelOutput!['model'], chat.defaultOptions.model);
       expect(res.usage?.promptTokens, isNotNull);
       expect(res.usage?.promptBillableCharacters, isNotNull);
       expect(res.usage?.responseTokens, isNotNull);