Obtain documents - DashVector - Alibaba Cloud Documentation Center

This topic describes how to obtain one or more documents in a collection based on the document ID or ID list by using the SDK for Java.

Note

If a specified ID does not exist, the corresponding output is empty.

Prerequisites

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

API definition

Java

// The DashVectorCollection class.

// The method working in synchronous mode.
public Response<Map<String, Doc>> fetch(FetchDocRequest fetchDocRequest);

// The method working in asynchronous mode.
public ListenableFuture<Response<Map<String, Doc>>> fetchAsync(FetchDocRequest fetchDocRequest);

Example

Note

You need to replace YOUR_API_KEY with your API key and YOUR_CLUSTER_ENDPOINT with the endpoint of your cluster in the sample code for the code to run properly.

You need to create a collection named quickstart in advance. For more information, see the "Example" section of the Create a collection topic. You also need to insert some documents in advance. For more information, see 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 {
        DashVectorClient client = new DashVectorClient("YOUR_API_KEY", "YOUR_CLUSTER_ENDPOINT");
        DashVectorCollection collection = client.get("quickstart");

        // Build a FetchDocRequest object.
        FetchDocRequest request = FetchDocRequest.builder()
            .id("1")
            .build();

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

        System.out.println(response);
        // Output example:
        // {
        //     "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
        //         }
        //     }
        // }
    }
}

Request parameters

You can use a FetchDocRequestBuilder instance to build a FetchDocRequest object. The following table describes the methods that can be called by the instance.

Method	Required	Default value	Description
ids(List<String> ids)	Yes	-	Sets the primary key or a list of primary keys of documents.
id(String id)	No	-
partition(String partition)	No	default	Sets the name of the partition.
build()	-	-	Builds a `FetchDocRequest` object.

Response parameters

Note

A Response<Map<String, Doc>> object is returned, which contains the operation result, as described in the following table.

Method	Type	Description	Example
getCode()	int	The returned status code. For more information, see Status codes.	0
getMessage()	String	The returned message.	success
getRequestId()	String	The unique ID of the request.	19215409-ea66-4db9-8764-26ce2eb5bb99
getOutput()	Map<String, Doc>	The map with the key set to the primary key and the value set to the Doc object.	`{ "1":{ "id":"1", "vector":{"value":[0.1,0.2,0.3,0.4]}, "fields":{"name":"zhangsan"}, "score":0 } }`
isSuccess()	Boolean	Specifies whether the operation is successful.	true