如何在v2 Go SDK中使用KeyConditionExpression查询AWS DynamoDb？

afdcj2ne 于 2023-11-14 发布在 Go

关注(0)|答案(1)|浏览(139)

我用以下命令在dynamodb中创建了一个现有表

aws dynamodb create-table \
  --region us-east-1 \
  --table-name notifications \
  --attribute-definitions AttributeName=CustomerId,AttributeType=S AttributeName=Timestamp,AttributeType=N AttributeName=MessageId,AttributeType=S \
  --key-schema AttributeName=CustomerId,KeyType=HASH AttributeName=Timestamp,KeyType=RANGE \
  --provisioned-throughput ReadCapacityUnits=5,WriteCapacityUnits=5 \
  --global-secondary-indexes '[
      {
          "IndexName": "MessageId",
          "KeySchema": [
              {
                  "AttributeName": "MessageId",
                  "KeyType": "HASH"
              }
          ],
          "Projection": {
              "ProjectionType": "ALL"
          },
          "ProvisionedThroughput": {
              "ReadCapacityUnits": 5,
              "WriteCapacityUnits": 5
          }
      }
  ]'
}

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我想在它前面放置一个API Package 器，它允许我从CustomerId提供的表中获取所有记录，因此我尝试使用v2 GO SDK中的查询

// GET /notifications/
func (api NotificationsApi) getNotifications(w http.ResponseWriter, r *http.Request) {
    var err error

    customerId := r.URL.Query().Get("customerId")
    if customerId == "" {
        api.errorResponse(w, "customerId query parameter required", http.StatusBadRequest)
        return
    }
    span, ctx := tracer.StartSpanFromContext(r.Context(), "notification.get")
    defer span.Finish(tracer.WithError(err))

    keyCond := expression.Key("CustomerId").Equal(expression.Value(":val"))
    expr, err := expression.NewBuilder().WithKeyCondition(keyCond).Build()

    input := &dynamodb.QueryInput{
        TableName:              aws.String("notifications"),
        KeyConditionExpression: expr.KeyCondition(),
        ExpressionAttributeValues: map[string]dynamodbTypes.AttributeValue{
            ":val": &dynamodbTypes.AttributeValueMemberS{Value: customerId},
        },
    }

    fmt.Println(*expr.KeyCondition())
    output, err := api.dynamoClient.Query(ctx, input)

    fmt.Println(output)
    fmt.Println(err)
}

型
但是，我从dynamodb得到了400分。

operation error DynamoDB: Query, https response error StatusCode: 400, RequestID: *****, api error ValidationException: Invalid KeyConditionExpression: An expression attribute name used in the document path is not defined; attribute name: #0

型
fmt.PrintLn(*expr.KeyCondition())的输出是#0 = :0
在本地运行此查询将返回预期结果

awslocal dynamodb query \
    --table-name notifications \
    --key-condition-expression "CustomerId = :val" \
    --expression-attribute-values '{":val":{"S":"localTesting"}}'

型
我也试过包含时间戳，但不认为这是必需的，因为我的终端命令没有它的作品。我不认为我解引用不当。我知道我的发电机会话是有效的，因为我可以张贴到我的 Package 器，并通过终端命令看到更新。

go

来源：https://stackoverflow.com/questions/77434444/how-to-query-aws-dynamodb-using-keyconditionexpression-with-the-v2-go-sdk

1条答案

按热度按时间

p8h8hvxi1#

下面是一个可以用作模板的查询示例：

// TableBasics encapsulates the Amazon DynamoDB service actions used in the examples.
// It contains a DynamoDB service client that is used to act on the specified table.
type TableBasics struct {
    DynamoDbClient *dynamodb.Client
    TableName      string
}


// Query gets all movies in the DynamoDB table that were released in the specified year.
// The function uses the `expression` package to build the key condition expression
// that is used in the query.
func (basics TableBasics) Query(releaseYear int) ([]Movie, error) {
    var err error
    var response *dynamodb.QueryOutput
    var movies []Movie
    keyEx := expression.Key("year").Equal(expression.Value(releaseYear))
    expr, err := expression.NewBuilder().WithKeyCondition(keyEx).Build()
    if err != nil {
        log.Printf("Couldn't build expression for query. Here's why: %v\n", err)
    } else {
        response, err = basics.DynamoDbClient.Query(context.TODO(), &dynamodb.QueryInput{
            TableName:                 aws.String(basics.TableName),
            ExpressionAttributeNames:  expr.Names(),
            ExpressionAttributeValues: expr.Values(),
            KeyConditionExpression:    expr.KeyCondition(),
        })
        if err != nil {
            log.Printf("Couldn't query for movies released in %v. Here's why: %v\n", releaseYear, err)
        } else {
            err = attributevalue.UnmarshalListOfMaps(response.Items, &movies)
            if err != nil {
                log.Printf("Couldn't unmarshal query response. Here's why: %v\n", err)
            }
        }
    }
    return movies, err
}

字符串
你可以在这里看到更多的GoV2示例

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如何在v2 Go SDK中使用KeyConditionExpression查询AWS DynamoDb？

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