Tukar AWS redshiftdataapiservice.GetStatementResultOutput kepada JSON atau struktur

Kandungan soalan

Saya mempunyai pangkalan data Tanpa Pelayan AWS Redshift yang saya tanya melalui AWS Go SDK redshiftdataapiservice. Pertanyaan dan semua yang berfungsi, tetapi rekod dikembalikan dalam format yang sukar untuk digunakan/difahami.

Kod saya seperti ini:

import (
    "fmt"
    "log"
    "time"
    "os"
    "context"

    "github.com/aws/aws-sdk-go-v2/aws"
    "github.com/aws/aws-sdk-go-v2/config"
    "github.com/aws/aws-sdk-go-v2/service/redshiftdata"
    "github.com/aws/aws-sdk-go-v2/service/redshiftdata/types"
)

// Execute a Redshift query and return a result statement output
func executeRedshiftQuery(sql string) (*redshiftdata.GetStatementResultOutput, error) {
    // Load the Shared AWS Configuration (~/.aws/config)
    cfg, err := config.LoadDefaultConfig(context.TODO(), config.WithRegion(os.Getenv("AWS_REGION")))
    if err != nil {
        return nil, err
    }

    // Create a service client
    redshiftclient := redshiftdata.NewFromConfig(cfg)
    execStmt, err := redshiftclient.ExecuteStatement(context.TODO(), &redshiftdata.ExecuteStatementInput{
        WorkgroupName: aws.String(os.Getenv("WG_NAME")),
        Database:      aws.String(os.Getenv("DB_NAME")),
        Sql:           aws.String(sql),
    })
    if err != nil {
        return nil, err
    }

    // wait for query to finish
    for {
        descStmt, err := redshiftclient.DescribeStatement(context.TODO(), &redshiftdata.DescribeStatementInput{
            Id: execStmt.Id,
        })
        if err != nil {
            return nil, err
        }

        // return an error if the query failed or aborted
        if descStmt.Status == types.StatusStringFailed || descStmt.Status == types.StatusStringAborted {
            err := errors.New("the Redshift query failed or was aborted")
            return nil, err
        } else if descStmt.Status != types.StatusStringFinished {
            time.Sleep(1 * time.Second)
            continue
        }

        break
    }

    // get the results
    resultStmt, err := redshiftclient.GetStatementResult(context.TODO(), &redshiftdata.GetStatementResultInput{
        Id: execStmt.Id,
    })
    if err != nil {
        return nil, err
    }

    return resultStmt, nil
}

Saya mendapati tatasusunan 2D *Field sukar untuk digunakan. Bagaimanakah saya (sebaik-baiknya hanya) memetakan ini kepada JSON yang boleh digunakan, atau lebih tepatnya pelbagai jenis struct? Atau adakah terdapat cara untuk meminta JSON daripada Redshift? Jika boleh, saya ingin menyimpan semua ini sepenuhnya dalam aplikasi Golang saya.

Jawapan betul

Saya tidak menjumpai cara rasmi, tetapi kaedah di bawah berfungsi dengan mencipta serpihan pemetaan nama lajur kepada nilai lajur dan kemudian keluarkan dari situ.

// Extracts the column name from column metadata for a given column index
func getColumnName(metadata []types.ColumnMetadata, index int) string {
    if index < len(metadata) {
        // We assume the metadata is in the same order as the columns in the record.
        // If the column name is not set or empty, we can fallback to a default naming convention.
        if metadata[index].Name != nil {
            return *metadata[index].Name
        }
        return fmt.Sprintf("column_%d", index)
    }
    // Fallback if the index is out of range of the metadata slice.
    return fmt.Sprintf("unknown_column_%d", index)
}

// Converts query results to JSON bytes for easy unmarshaling to structs
func queryResultsToJSON(query_results *redshiftdata.GetStatementResultOutput) ([]byte, error) {
    // Convert the records to a slice of maps for JSON conversion
    var records []map[string]interface{}

    for _, row := range query_results.Records {
        record := make(map[string]interface{})
        for idx, col := range row {
            // Use the column metadata to determine the name of the column
            columnName := getColumnName(query_results.ColumnMetadata, idx)

            // Check the type of the value and assign it to the record map
            var value interface{}
            switch v := col.(type) {
            case *types.FieldMemberBlobValue:
                value = v.Value
            case *types.FieldMemberBooleanValue:
                value = v.Value
            case *types.FieldMemberDoubleValue:
                value = v.Value
            case *types.FieldMemberIsNull:
                value = nil
            case *types.FieldMemberLongValue:
                value = v.Value
            case *types.FieldMemberStringValue:
                value = v.Value
            }
            record[columnName] = value
        }
        records = append(records, record)
    }

    // Marshal the records to JSON
    jsonBytes, err := json.Marshal(records)
    if err != nil {
        log.Error("failed to marshal records to JSON, " + err.Error())
        return nil, err
    }

    return jsonBytes, nil
}

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