读取对象

您可以不查询数据库，而使用 ID 来检索单个对象。

其他信息

对象 CRUD 操作中的集合（类）名称

集合充当命名空间，因此两个不同的集合之间可能存在重复的 ID。

在 Weaviate v1.14 之前，您可以无需指定集合名称即可操作对象。此方法已被弃用。它将在 Weaviate v2.0.0 中删除。

从 v1.20 开始，您可以拥有 多租户 数据集。当 multi-tenancy 启用时，需要租户名称。

始终包含集合名称，并在启用时包含租户名称。

通过 ID 获取对象

使用 ID 检索对象。如果 ID 不存在，Weaviate 将返回 404 错误。

PythonJavaScript/TypeScriptGoJava v6Java v5 (已弃用)C#

  API 文档

更多信息文档中的代码片段反映了最新的客户端库和 Weaviate 数据库版本。请查看 发行说明 以获取特定版本。

如果某个片段无法工作或您有任何反馈，请打开一个 GitHub issue。

jeopardy = client.collections.use("JeopardyQuestion")

data_object = jeopardy.query.fetch_object_by_id("00ff6900-e64f-5d94-90db-c8cfa3fc851b")

print(data_object.properties)

const jeopardy = client.collections.use('JeopardyQuestion')

const response = await jeopardy.query.fetchObjectById('ed89d9e7-4c9d-4a6a-8d20-095cb0026f54')

console.log(response?.properties)

objects, err := client.Data().ObjectsGetter().
  WithClassName("JeopardyQuestion").
  WithID("00ff6900-e64f-5d94-90db-c8cfa3fc851b").
  Do(ctx)
if err != nil {
  // handle error
  panic(err)
}

for i, obj := range objects {
  fmt.Printf("object[%v]: %+v\n", i, *obj)
}

CollectionHandle<Map<String, Object>> jeopardy = client.collections.use("JeopardyQuestion");

var dataObjectOpt = jeopardy.query.fetchObjectById("00ff6900-e64f-5d94-90db-c8cfa3fc851b");

dataObjectOpt.ifPresent(dataObject -> System.out.println(dataObject.properties()));

Result<List<WeaviateObject>> result = client.data().objectsGetter()
  .withClassName("JeopardyQuestion")
  .withID("00ff6900-e64f-5d94-90db-c8cfa3fc851b")
  .run();

System.out.println(result.getResult());

var jeopardy = client.Collections.Use("JeopardyQuestion");

var dataObject = await jeopardy.Query.FetchObjectByID(
    Guid.Parse("00ff6900-e64f-5d94-90db-c8cfa3fc851b")
);

if (dataObject != null)
{
    Console.WriteLine(JsonSerializer.Serialize(dataObject.Properties));
}

返回的属性

默认情况下，将返回所有属性和对象 UUID。除非另有说明，否则将排除 Blob 和引用属性。这不适用于 Go 和 Java v5 客户端库。

检索对象的向量

可以通过指定其返回来检索对象向量。

PythonJavaScript/TypeScriptGoJava v6Java v5 (已弃用)C#

  API 文档

更多信息文档中的代码片段反映了最新的客户端库和 Weaviate 数据库版本。请查看 发行说明 以获取特定版本。

如果某个片段无法工作或您有任何反馈，请打开一个 GitHub issue。

jeopardy = client.collections.use("JeopardyQuestion")

data_object = jeopardy.query.fetch_object_by_id(
    "00ff6900-e64f-5d94-90db-c8cfa3fc851b",
    include_vector=True
)

print(data_object.vector["default"])

const jeopardy = client.collections.use('JeopardyQuestion')

const response = await jeopardy.query.fetchObjectById('ed89d9e7-4c9d-4a6a-8d20-095cb0026f54',{
  includeVector: true
})

console.log(response?.properties)

objects, err := client.Data().ObjectsGetter().
  WithClassName("JeopardyQuestion").
  WithID("00ff6900-e64f-5d94-90db-c8cfa3fc851b").
  WithVector().
  Do(ctx)
if err != nil {
  // handle error
  panic(err)
}

for i, obj := range objects {
  fmt.Printf("object[%v]: %+v\n", i, *obj)
}

CollectionHandle<Map<String, Object>> jeopardy = client.collections.use("JeopardyQuestion");

var dataObjectOpt = jeopardy.query.fetchObjectById("00ff6900-e64f-5d94-90db-c8cfa3fc851b",
    q -> q.includeVector()
);

dataObjectOpt.ifPresent(dataObject -> System.out
    .println(Arrays.toString(dataObject.vectors().getSingle("default"))));

Result<List<WeaviateObject>> result = client.data().objectsGetter()
  .withClassName("JeopardyQuestion")
  .withID("00ff6900-e64f-5d94-90db-c8cfa3fc851b")
  .withVector()
  // handle error
  .run();

System.out.println(result.getResult());

var jeopardy = client.Collections.Use("JeopardyQuestion");

var dataObject = await jeopardy.Query.FetchObjectByID(
    Guid.Parse("00ff6900-e64f-5d94-90db-c8cfa3fc851b"),
    includeVectors: true
);

if (dataObject?.Vectors.ContainsKey("default") ?? false)
{
    var vector = dataObject.Vectors["default"];
    Console.WriteLine(vector);
}

检索命名向量

在使用命名向量的情况下，可以通过指定其名称来检索一个或多个向量。

PythonJavaScript/TypeScriptJava v6C#

  API 文档

更多信息文档中的代码片段反映了最新的客户端库和 Weaviate 数据库版本。请查看 发行说明 以获取特定版本。

如果某个片段无法工作或您有任何反馈，请打开一个 GitHub issue。

reviews = client.collections.use("WineReviewNV")  # Collection with named vectors
vector_names = ["title", "review_body"]

data_object = reviews.query.fetch_object_by_id(
    uuid=obj_uuid,  # Object UUID
    include_vector=vector_names  # Specify names of the vectors to include
)

# The vectors are returned in the `vector` property as a dictionary
for n in vector_names:
    print(f"Vector '{n}': {data_object.vector[n][:5]}...")

const reviews = client.collections.use('WineReviewNV') // Collection with named vectors
const objectUuid = '' // Object UUID

const response = await reviews.query.fetchObjectById(objectUuid,{
  includeVector: ['title', 'review_body']
})

console.log(response?.vectors.title)       // print the title vector
console.log(response?.vectors.review_body) // print the review_body vector

CollectionHandle<Map<String, Object>> reviews = client.collections.use("WineReviewNV"); // Collection with named

var dataObjectOpt = reviews.query.fetchObjectById(objUuid, // Object UUID
    q -> q.includeVector(vectorNames) // Specify to include vectors
);

// The vectors are returned in the `vectors` property as a dictionary
dataObjectOpt.ifPresent(dataObject -> {
  for (String n : vectorNames) {
    float[] vector = dataObject.vectors().getSingle(n);
    if (vector != null) {
      System.out.printf("Vector '%s': %s...\n", n, Arrays.toString(Arrays.copyOf(vector, 5)));
    }
  }
});

var reviews = client.Collections.Use("WineReviewNV"); // Collection with named
var dataObject = await reviews.Query.FetchObjectByID(
    objUuid.Value, // Object UUID
    includeVectors: true // Specify to include vectors
);

// The vectors are returned in the `Vectors` property as a dictionary
if (dataObject != null)
{
    foreach (var name in vectorNames)
    {
        if (dataObject.Vectors.TryGetValue(name, out var vector))
        {
            Console.WriteLine(vector);
        }
    }
}

检查对象是否存在

为了有效地检查具有给定 id 的对象是否存在，而无需检索它，请向 /v1/objects/ REST 端点 发送 HEAD 请求，或使用以下客户端代码

PythonJavaScript/TypeScriptGoJava v6Java v5 (已弃用)C#

  API 文档

更多信息文档中的代码片段反映了最新的客户端库和 Weaviate 数据库版本。请查看 发行说明 以获取特定版本。

如果某个片段无法工作或您有任何反馈，请打开一个 GitHub issue。

# generate uuid based on the key properties used during data insert
object_uuid = generate_uuid5({"name": "Author to fetch"})

authors = client.collections.use("Author")
author_exists = authors.data.exists(object_uuid)

print("Author exist: ", author_exists)

import { generateUuid5 } from 'weaviate-client';

// generate uuid based on the key properties used during data insert
const object_uuid = generateUuid5(
  JSON.stringify({ name: "Author to fetch"})
)

const authors = await client.collections.use('Author')
const authorExists = await authors.data.exists(object_uuid)

console.log('Author exists: ' + authorExists)

package main

import (
  "context"
  "fmt"

  "github.com/weaviate/weaviate-go-client/v5/weaviate"
  "github.com/weaviate/weaviate-go-client/v5/weaviate/data/replication"  // for consistency levels
)

func main() {
  cfg := weaviate.Config{
    Host:   "localhost:8080",
    Scheme: "http",
  }
  client, err := weaviate.NewClient(cfg)
  if err != nil {
    panic(err)
  }

  exists, err := client.Data().Checker().
    WithClassName("MyClass").
    WithID("36ddd591-2dee-4e7e-a3cc-eb86d30a0923").
    WithConsistencyLevel(replication.ConsistencyLevel.ONE).  // default QUORUM
    Do(context.Background())

  if err != nil {
    panic(err)
  }
  fmt.Printf("%v", exists)
}

// The parameter passed to "WithConsistencyLevel" can be one of:
// * replication.ConsistencyLevel.ALL,
// * replication.ConsistencyLevel.QUORUM, or
// * replication.ConsistencyLevel.ONE.
//
// It determines how many replicas must acknowledge a request
// before it is considered successful.

CollectionHandle<Map<String, Object>> jeopardy = client.collections.use("JeopardyQuestion");
boolean exists = jeopardy.data.exists("00ff6900-e64f-5d94-90db-c8cfa3fc851b");
System.out.println(exists);

package io.weaviate;

import io.weaviate.client.Config;
import io.weaviate.client.WeaviateClient;
import io.weaviate.client.base.Result;
import io.weaviate.client.v1.data.replication.model.ConsistencyLevel;

public class App {
  public static void main(String[] args) {
    Config config = new Config("http", "localhost:8080");
    WeaviateClient client = new WeaviateClient(config);

    Result<Boolean> result = client.data().checker()
      .withClassName("MyClass")
      .withID("36ddd591-2dee-4e7e-a3cc-eb86d30a4303")
      .withConsistencyLevel(ConsistencyLevel.ONE)  // default QUORUM
      .run();

    if (result.hasErrors()) {
      System.out.println(result.getError());
      return;
    }
    System.out.println(result.getResult());
  }
}

// The parameter passed to `withConsistencyLevel` can be one of:
// * ConsistencyLevel.ALL,
// * ConsistencyLevel.QUORUM, or
// * ConsistencyLevel.ONE.
//
// It determines how many replicas must acknowledge a request
// before it is considered successful.

var jeopardy = client.Collections.Use("JeopardyQuestion");

// The C# client checks for existence by attempting to fetch an object and checking for null.
var dataObject = await jeopardy.Query.FetchObjectByID(
    Guid.Parse("00ff6900-e64f-5d94-90db-c8cfa3fc851b")
);
bool exists = dataObject != null;

Console.WriteLine(exists);

相关页面

• 连接到 Weaviate
• 操作指南：搜索
• 操作方法：读取所有对象

• 参考：REST - /v1/objects

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