Weaviate

This section will walk you through setting up the Weaviate VectorStore to store document embeddings and perform similarity searches.

What is Weaviate?

Weaviate is an open-source vector database. It allows you to store data objects and vector embeddings from your favorite ML-models and scale seamlessly into billions of data objects. It provides tools to store document embeddings, content, and metadata and to search through those embeddings, including metadata filtering.

Prerequisites

  1. EmbeddingClient instance to compute the document embeddings. Several options are available:

    • Transformers Embedding - computes the embedding in your local environment. Follow the ONNX Transformers Embedding instructions.

    • OpenAI Embedding - uses the OpenAI embedding endpoint. You need to create an account at OpenAI Signup and generate the api-key token at API Keys.

    • You can also use the Azure OpenAI Embedding or the PostgresML Embedding Client.

  2. Weaviate cluster. You can set up a cluster locally in a Docker container or create a Weaviate Cloud Service. For the latter, you need to create a Weaviate account, set up a cluster, and get your access API key from the dashboard details.

On startup, the WeaviateVectorStore creates the required SpringAiWeaviate object schema if it’s not already provisioned.

Dependencies

Add these dependencies to your project:

  • Embedding Client boot starter, required for calculating embeddings.

  • Transformers Embedding (Local) and follow the ONNX Transformers Embedding instructions.

<dependency>
  <groupId>org.springframework.ai</groupId>
  <artifactId>spring-ai-transformers-spring-boot-starter</artifactId>
</dependency>

or use OpenAI (Cloud)

<dependency>
    <groupId>org.springframework.ai</groupId>
    <artifactId>spring-ai-openai-spring-boot-starter</artifactId>
</dependency>

You’ll need to provide your OpenAI API Key. Set it as an environment variable like so:

export SPRING_AI_OPENAI_API_KEY='Your_OpenAI_API_Key'
  • Add the Weaviate VectorStore dependency

<dependency>
  <groupId>org.springframework.ai</groupId>
  <artifactId>spring-ai-weaviate-store</artifactId>
</dependency>
Refer to the Dependency Management section to add the Spring AI BOM to your build file.

Usage

Create a WeaviateVectorStore instance connected to the local Weaviate cluster:

@Bean
public VectorStore vectorStore(EmbeddingClient embeddingClient) {
  WeaviateVectorStoreConfig config = WeaviateVectorStoreConfig.builder()
     .withScheme("http")
     .withHost("localhost:8080")
     // Define the metadata fields to be used
     // in the similarity search filters.
     .withFilterableMetadataFields(List.of(
        MetadataField.text("country"),
        MetadataField.number("year"),
        MetadataField.bool("active")))
     // Consistency level can be: ONE, QUORUM, or ALL.
     .withConsistencyLevel(ConsistentLevel.ONE)
     .build();

  return new WeaviateVectorStore(config, embeddingClient);
}
You must list explicitly all metadata field names and types (BOOLEAN, TEXT, or NUMBER) for any metadata key used in filter expression. The withFilterableMetadataKeys above registers filterable metadata fields: country of type TEXT, year of type NUMBER, and active of type BOOLEAN.

If the filterable metadata fields are expanded with new entries, you have to (re)upload/update the documents with this metadata.

You can use the following Weaviate system metadata fields without explicit definition: id, _creationTimeUnix, and _lastUpdateTimeUnix.

Then in your main code, create some documents:

List<Document> documents = List.of(
   new Document("Spring AI rocks!! Spring AI rocks!! Spring AI rocks!! Spring AI rocks!! Spring AI rocks!!", Map.of("country", "UK", "active", true, "year", 2020)),
   new Document("The World is Big and Salvation Lurks Around the Corner", Map.of()),
   new Document("You walk forward facing the past and you turn back toward the future.", Map.of("country", "NL", "active", false, "year", 2023)));

Now add the documents to your vector store:

vectorStore.add(List.of(document));

And finally, retrieve documents similar to a query:

List<Document> results = vectorStore.similaritySearch(
   SearchRequest
      .query("Spring")
      .withTopK(5));

If all goes well, you should retrieve the document containing the text "Spring AI rocks!!".

Metadata filtering

You can leverage the generic, portable metadata filters with WeaviateVectorStore as well.

For example, you can use either the text expression language:

vectorStore.similaritySearch(
   SearchRequest
      .query("The World")
      .withTopK(TOP_K)
      .withSimilarityThreshold(SIMILARITY_THRESHOLD)
      .withFilterExpression("country in ['UK', 'NL'] && year >= 2020"));

or programmatically using the expression DSL:

FilterExpressionBuilder b = new FilterExpressionBuilder();

vectorStore.similaritySearch(
   SearchRequest
      .query("The World")
      .withTopK(TOP_K)
      .withSimilarityThreshold(SIMILARITY_THRESHOLD)
      .withFilterExpression(b.and(
         b.in("country", "UK", "NL"),
         b.gte("year", 2020)).build()));

The portable filter expressions get automatically converted into the proprietary Weaviate where filters. For example, the following portable filter expression:

country in ['UK', 'NL'] && year >= 2020

is converted into Weaviate GraphQL where filter expression:

operator:And
   operands:
      [{
         operator:Or
         operands:
            [{
               path:["meta_country"]
               operator:Equal
               valueText:"UK"
            },
            {
               path:["meta_country"]
               operator:Equal
               valueText:"NL"
            }]
      },
      {
         path:["meta_year"]
         operator:GreaterThanEqual
         valueNumber:2020
      }]

Run Weaviate cluster in docker container

Start Weaviate in a docker container:

docker run -it --rm --name weaviate -e AUTHENTICATION_ANONYMOUS_ACCESS_ENABLED=true -e PERSISTENCE_DATA_PATH=/var/lib/weaviate -e QUERY_DEFAULTS_LIMIT=25 -e DEFAULT_VECTORIZER_MODULE=none -e CLUSTER_HOSTNAME=node1 -p 8080:8080 semitechnologies/weaviate:1.22.4

Starts a Weaviate cluster at localhost:8080/v1 with scheme=http, host=localhost:8080, and apiKey="". Then follow the usage instructions.