如何使用 AWS sdk 在 Go 中正确解组 PartiQL 查询的结果？

问题内容

我的乐队即将演出的节目存储在 DynamoDB 中，并且我有以下代码：

type PartiQLRunner struct {
DynamoDbClient *dynamodb.DynamoDB
TableName string
}

func BuildRunner() *PartiQLRunner {
sess := session.Must(session.NewSessionWithOptions(session.Options{
SharedConfigState: session.SharedConfigEnable,
}))

svc := dynamodb.New(sess)

return &PartiQLRunner{
DynamoDbClient: svc,
TableName: "SHOWS",
}
}

type Show struct {
PK int `dynamodbav:"PK"`
DATE string `dynamodbav:"DATE"`
ADDRESS string `dynamodbav:"ADDRESS"`
VENUE string `dynamodbav:"VENUE"`
}

func (runner PartiQLRunner) GetShows() ([]Show, error) {
var shows []Show
response, err := runner.DynamoDbClient.ExecuteStatement(
&dynamodb.ExecuteStatementInput{
Statement: aws.String(fmt.Sprintf("SELECT * FROM "%v" WHERE PK = 1", runner.TableName)),
})
if err != nil {
log.Printf("Couldn't get info. Here's why: %vn", err)
} else {
err = attributevalue.UnmarshalListOfMaps(response.Items, &shows)
if err != nil {
log.Printf("Couldn't unmarshal response. Here's why: %vn", err)
}
}
return shows, err
}

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但是，我在 UnmarshalListOfMaps() 中的 response.Items 参数中收到以下错误：

无法使用“response.Items”（类型[]map[string]*AttributeValue）作为类型[]map[string]types.AttributeValue

我对 Go 语法仍然有些陌生，我不确定我是否理解传入内容与预期内容之间的不匹配。任何帮助将不胜感激。

解决方法

似乎 UnmarshalListOfMaps 函数期望的内容与您提供的内容之间存在类型不匹配。该错误消息表明该函数需要 []map[string]types.AttributeValue 类型的参数，但 response.Items 的类型为 []map[string]*AttributeValue。

解决方案是将 response.Items 转换为正确的类型或为您的切片使用正确的类型签名。

解决此问题的方法如下：

package main

import (
"fmt"
"log"

"github.com/aws/aws-sdk-go-v2/aws"
"github.com/aws/aws-sdk-go-v2/service/dynamodb"
"github.com/aws/aws-sdk-go-v2/service/dynamodb/attributevalue"
"github.com/aws/aws-sdk-go-v2/service/dynamodb/types"
)

type Show struct {
PK int `dynamodbav:"PK"`
DATE string `dynamodbav:"DATE"`
ADDRESS string `dynamodbav:"ADDRESS"`
VENUE string `dynamodbav:"VENUE"`
}

type PartiQLRunner struct {
DynamoDbClient *dynamodb.Client
TableName string
}

func (runner PartiQLRunner) GetShows() ([]*Show, error) {
var shows []*Show

response, err := runner.DynamoDbClient.ExecuteStatement(
&dynamodb.ExecuteStatementInput{
Statement: aws.String(fmt.Sprintf("SELECT * FROM "%v" WHERE PK = 1", runner.TableName)),
})
if err != nil {
log.Printf("Couldn't get info. Here's why: %vn", err)
return shows, err
}

err = attributevalue.UnmarshalListOfMaps(response.Items, &shows)
if err != nil {
log.Printf("Couldn't unmarshal response. Here's why: %vn", err)
return shows, err
}

return shows, nil
}

// The main function is just for demonstration and may not be part of your code
func main() {
// You will need to initialize your DynamoDbClient and TableName
runner := PartiQLRunner{
DynamoDbClient: /* initialize your DynamoDB client here */,
TableName: "YourTableName",
}

shows, err := runner.GetShows()
if err != nil {
log.Fatalf("Error retrieving shows: %v", err)
}

for _, show := range shows {
fmt.Printf("Show Date: %s, Venue: %s, Address: %sn", show.DATE, show.VENUE, show.ADDRESS)
}
}

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请确保您具有适当的 DynamoDB 客户端初始化逻辑（在 main 函数中注释掉）来建立与 DynamoDB 的连接。

所提供的代码现在可以正确地将响应解组为指向 Show 结构的指针片段。

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