Fetch a doc-DashVector(DashVector)-阿里云帮助中心

Retrieve one or more documents from a collection by primary key using the DashVector Java SDK. If a specified ID does not exist, the corresponding output is empty.

Prerequisites

Before you begin, make sure that you have:

A DashVector cluster. For more information, see Create a cluster
An API key. For more information, see Manage API keys
The latest version of the DashVector SDK. For more information, see Install DashVector SDK

API definition

The DashVectorCollection class provides both synchronous and asynchronous methods for fetching documents:

Java

// Synchronous
public Response<Map<String, Doc>> fetch(FetchDocRequest fetchDocRequest);

// Asynchronous
public ListenableFuture<Response<Map<String, Doc>>> fetchAsync(FetchDocRequest fetchDocRequest);

Request parameters

Use FetchDocRequestBuilder to construct a FetchDocRequest object.

Method	Required	Default value	Description
`ids(List<String> ids)`	Yes	-	The primary keys of the documents to fetch.
`id(String id)`	No	-	A single document primary key.
`partition(String partition)`	No	default	The partition to fetch from.
`build()`	-	-	Builds the `FetchDocRequest` object.

Example

This example fetches a single document by ID from the quickstart collection.

Replace the placeholders with your actual values:

Placeholder	Description
`<YOUR_API_KEY>`	Your DashVector API key
`<YOUR_CLUSTER_ENDPOINT>`	Your cluster endpoint

Note

This example requires a collection named quickstart with existing documents. See Create a collection and Insert documents.

Java

import com.aliyun.dashvector.DashVectorClient;
import com.aliyun.dashvector.DashVectorCollection;
import com.aliyun.dashvector.common.DashVectorException;
import com.aliyun.dashvector.models.Doc;
import com.aliyun.dashvector.models.requests.FetchDocRequest;
import com.aliyun.dashvector.models.responses.Response;

import java.util.Map;

public class Main {
    public static void main(String[] args) throws DashVectorException {
        // Initialize the client
        DashVectorClient client = new DashVectorClient("<YOUR_API_KEY>", "<YOUR_CLUSTER_ENDPOINT>");
        DashVectorCollection collection = client.get("quickstart");

        // Build a fetch request for document ID "1"
        FetchDocRequest request = FetchDocRequest.builder()
            .id("1")
            .build();

        // Fetch the document
        Response<Map<String, Doc>> response = collection.fetch(request);

        System.out.println(response);
    }
}

Sample response:

{
    "code": 0,
    "message": "Success",
    "requestId": "489c5cda-3ffc-4171-b6e0-1837b932962b",
    "output": {
        "1": {
            "id": "1",
            "vector": {"value": [0.1, 0.2, 0.3, 0.4]},
            "fields": {
                "name": "zhangsan",
                "age": 20,
                "weight": 100.0,
                "anykey1": "String",
                "anykey2": 1,
                "anykey3": true,
                "anykey4": 3.1415926
            },
            "score": 0
        }
    }
}

Response parameters

The fetch method returns a Response<Map<String, Doc>> object.

Method	Type	Description	Example
`getCode()`	int	The status code. For more information, see Status codes.	0
`getMessage()`	String	The response message.	success
`getRequestId()`	String	The unique request ID.	19215409-ea66-4db9-8764-26ce2eb5bb99
`getOutput()`	Map<String, Doc>	A map of primary keys to Doc objects.	See the sample response above.
getUsage()	RequestUsage	For a doc fetch request to a collection in a pay-as-you-go serverless instance, this method returns the number of read request units (RUs) consumed if the request is successful.
`isSuccess()`	Boolean	Whether the operation succeeded.	true