如何使用 AWS sdk 在 Go 中正確解組 PartiQL 查詢的結果？

問題內容

我的樂團即將演出的節目儲存在 DynamoDB 中，並且我有以下程式碼：

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

但是，我在 UnmarshalListOfMaps() 中的 response.Items 參數中收到以下錯誤：

無法使用「response.Items」（型別[]map[string]*AttributeValue）作為型別[]map[string]types.AttributeValue

我對 Go 語法仍然有些陌生，我不確定我是否理解傳入內容與預期內容之間的不匹配。任何幫助將不勝感激。

解決方法

似乎 UnmarshalListOfMaps 函數期望的內容與您提供的內容之間存在類型不符。這個錯誤訊息表示該函數需要[]map[string]types.AttributeValue 類型的參數，但response.Items 的類型為[]map[string]*AttributeValue 。

解決方案是將 response.Items 轉換為正確的類型或為您的切片使用正確的類型簽署。

解決此問題的方法如下：

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: %v\n", err)
        return shows, err
    }

    err = attributevalue.UnmarshalListOfMaps(response.Items, &shows)
    if err != nil {
        log.Printf("Couldn't unmarshal response. Here's why: %v\n", 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: %s\n", show.DATE, show.VENUE, show.ADDRESS)
    }
}

請確保您具有適當的 DynamoDB 用戶端初始化邏輯（在 main 函數中註解掉）來建立與 DynamoDB 的連線。

所提供的程式碼現在可以正確地將回應解組為指向 Show 結構的指標片段。

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