feat(retrievers)!: Move all retriever config options to RetrieverOptions

docs/expression_language/cookbook/retrieval.md

@@ -164,7 +164,9 @@ In this example, we will add a memory to the chain and return the source documen
 
 ```dart
 final retriever = vectorStore.asRetriever(
-  searchType: const VectorStoreSimilaritySearch(k: 1),
+  defaultOptions: const VectorStoreRetrieverOptions(
+    searchType: VectorStoreSimilaritySearch(k: 1),
+  ),
 );
 final model = ChatOpenAI(apiKey: openaiApiKey);
 final stringOutputParser = const StringOutputParser();

examples/docs_examples/bin/expression_language/cookbook/retrieval.dart

@@ -190,7 +190,9 @@ Future<void> _conversationalRetrievalChainMemoryAndDocs() async {
   final vectorStore = Chroma(embeddings: embeddings);
 
   final retriever = vectorStore.asRetriever(
-    searchType: const VectorStoreSimilaritySearch(k: 1),
+    defaultOptions: const VectorStoreRetrieverOptions(
+      searchType: VectorStoreSimilaritySearch(k: 1),
+    ),
   );
   final model = ChatOpenAI(apiKey: openaiApiKey);
   const stringOutputParser = StringOutputParser();

packages/langchain/lib/src/chains/retrieval_qa.dart

@@ -72,7 +72,7 @@ class RetrievalQAChain extends BaseChain {
   });
 
   /// Retriever to use.
-  final BaseRetriever retriever;
+  final Retriever retriever;
 
   /// Chain to use to combine the documents.
   final BaseCombineDocumentsChain combineDocumentsChain;
@@ -111,7 +111,7 @@ class RetrievalQAChain extends BaseChain {
   String get chainType => 'retrieval_qa';
 
   /// Creates a [RetrievalQAChain] from a [BaseLanguageModel] and a
-  /// [BaseRetriever].
+  /// [Retriever].
   ///
   /// By default, it uses a prompt template optimized for question answering
   /// that includes the retrieved documents and the question.
@@ -134,7 +134,7 @@ class RetrievalQAChain extends BaseChain {
   /// [prompt]. Use 'context' and 'question' as the variable names.
   factory RetrievalQAChain.fromLlm({
     required final BaseLanguageModel llm,
-    required final BaseRetriever retriever,
+    required final Retriever retriever,
     final PromptTemplate? prompt,
   }) {
     return RetrievalQAChain(

packages/langchain/lib/src/documents/retrievers/base.dart

@@ -1,27 +1,33 @@
 import '../../core/core.dart';
 import '../models/models.dart';
+import 'models/models.dart';
 
 /// {@template base_retriever}
 /// Base Index class. All indexes should extend this class.
 /// {@endtemplate}
-abstract class BaseRetriever
-    extends Runnable<String, BaseLangChainOptions, List<Document>> {
+abstract class Retriever<Options extends RetrieverOptions>
+    extends Runnable<String, Options, List<Document>> {
   /// {@macro base_retriever}
-  const BaseRetriever();
+  const Retriever();
 
   /// Get the most relevant documents for a given query.
   ///
   /// - [input] - The query to search for.
+  /// - [options] - Retrieval options.
   @override
   Future<List<Document>> invoke(
     final String input, {
-    final BaseLangChainOptions? options,
+    final Options? options,
   }) {
-    return getRelevantDocuments(input);
+    return getRelevantDocuments(input, options: options);
   }
 
   /// Get the most relevant documents for a given query.
   ///
   /// - [query] - The query to search for.
-  Future<List<Document>> getRelevantDocuments(final String query);
+  /// - [options] - Retrieval options.
+  Future<List<Document>> getRelevantDocuments(
+    final String query, {
+    final Options? options,
+  });
 }

packages/langchain/lib/src/documents/retrievers/fake.dart

@@ -1,19 +1,23 @@
 import '../models/models.dart';
 import 'base.dart';
+import 'models/models.dart';
 
 /// {@template fake_retriever}
 /// A retriever that returns a fixed list of documents.
 /// This class is meant for testing purposes only.
 /// {@endtemplate}
-class FakeRetriever extends BaseRetriever {
+class FakeRetriever extends Retriever<RetrieverOptions> {
   /// {@macro fake_retriever}
   const FakeRetriever(this.docs);
 
   /// The documents to return.
   final List<Document> docs;
 
   @override
-  Future<List<Document>> getRelevantDocuments(final String query) {
+  Future<List<Document>> getRelevantDocuments(
+    final String query, {
+    final RetrieverOptions? options,
+  }) {
     return Future.value(docs);
   }
 }

packages/langchain/lib/src/documents/retrievers/models/models.dart

@@ -0,0 +1,29 @@
+import 'package:meta/meta.dart';
+
+import '../../../core/base.dart';
+import '../../vector_stores/models/models.dart';
+import '../retrievers.dart';
+
+/// {@template retriever_options}
+/// Base class for [Retriever] options.
+/// {@endtemplate}
+@immutable
+class RetrieverOptions extends BaseLangChainOptions {
+  /// {@macro retriever_options}
+  const RetrieverOptions();
+}
+
+/// {@template vector_store_retriever_options}
+/// Options for [VectorStoreRetriever].
+/// {@endtemplate}
+class VectorStoreRetrieverOptions extends RetrieverOptions {
+  /// {@macro vector_store_retriever_options}
+  const VectorStoreRetrieverOptions({
+    this.searchType = const VectorStoreSimilaritySearch(),
+  });
+
+  /// The type of search to perform, either:
+  /// - [VectorStoreSearchType.similarity] (default)
+  /// - [VectorStoreSearchType.mmr]
+  final VectorStoreSearchType searchType;
+}

packages/langchain/lib/src/documents/retrievers/retrievers.dart

@@ -1,3 +1,4 @@
 export 'base.dart';
 export 'fake.dart';
+export 'models/models.dart';
 export 'vector_store.dart';

packages/langchain/lib/src/documents/retrievers/vector_store.dart

@@ -1,25 +1,33 @@
 import '../models/models.dart';
 import '../vector_stores/vector_stores.dart';
 import 'base.dart';
+import 'models/models.dart';
 
 /// {@template vector_store_retriever}
 /// A retriever that uses a vector store to retrieve documents.
 /// {@endtemplate}
-class VectorStoreRetriever<V extends VectorStore> extends BaseRetriever {
+class VectorStoreRetriever<V extends VectorStore>
+    extends Retriever<VectorStoreRetrieverOptions> {
   /// {@macro vector_store_retriever}
   const VectorStoreRetriever({
     required this.vectorStore,
-    this.searchType = const VectorStoreSimilaritySearch(),
+    this.defaultOptions = const VectorStoreRetrieverOptions(),
   });
 
   /// The vector store to retrieve documents from.
   final V vectorStore;
 
-  /// The type of search to perform.
-  final VectorStoreSearchType searchType;
+  /// Default options for this retriever.
+  final VectorStoreRetrieverOptions defaultOptions;
 
   @override
-  Future<List<Document>> getRelevantDocuments(final String query) {
-    return vectorStore.search(query: query, searchType: searchType);
+  Future<List<Document>> getRelevantDocuments(
+    final String query, {
+    final VectorStoreRetrieverOptions? options,
+  }) {
+    return vectorStore.search(
+      query: query,
+      searchType: options?.searchType ?? defaultOptions.searchType,
+    );
   }
 }

packages/langchain/lib/src/documents/vector_stores/base.dart

@@ -1,6 +1,7 @@
 // ignore_for_file: avoid_unused_constructor_parameters
 import '../embeddings/base.dart';
 import '../models/models.dart';
+import '../retrievers/models/models.dart';
 import '../retrievers/vector_store.dart';
 import 'models/models.dart';
 
@@ -170,16 +171,14 @@ abstract class VectorStore {
 
   /// Returns a [VectorStoreRetriever] that uses this vector store.
   ///
-  /// - [searchType] is the type of search to perform, either
-  ///   [VectorStoreSearchType.similarity] (default) or
-  ///   [VectorStoreSearchType.mmr].
+  /// - [defaultOptions] are the default options for the retriever.
   VectorStoreRetriever asRetriever({
-    final VectorStoreSearchType searchType =
-        const VectorStoreSimilaritySearch(),
+    final VectorStoreRetrieverOptions defaultOptions =
+        const VectorStoreRetrieverOptions(),
   }) {
     return VectorStoreRetriever(
       vectorStore: this,
-      searchType: searchType,
+      defaultOptions: defaultOptions,
     );
   }
 }