How to Efficiently Map Database Rows to Maps in Golang?

How to Create a Map from Database Rows in Golang

In the database/sql package, the Rows.Scan() function requires a specific number of parameters matching the columns in a query. This can be limiting when working with unknown or varying datasets. To create a map from database rows in a more generalized manner, consider the following approach:

Using sqlx Library

The sqlx library provides an alternative to the database/sql package that simplifies the task of creating a map from database rows:

// Define the function to create a map from rows
func RowsToMap(rows *sql.Rows) ([]map[string]interface{}, error) {

    // Define the list to store the data
    data := []map[string]interface{}{}

    // Get the column names
    columns, err := rows.Columns()
    if err != nil {
        return nil, err
    }

    // Create a slice of interface{} to hold the data for each row
    values := make([]interface{}, len(columns))

    // Create a slice of pointers to the values
    valuePtrs := make([]interface{}, len(columns))
    for i, _ := range values {
        valuePtrs[i] = &values[i]
    }

    // Loop through the rows and add to the data list
    for rows.Next() {
        // Scan the row into the values slice
        err = rows.Scan(valuePtrs...)
        if err != nil {
            return nil, err
        }

        // Create a map to hold the data for the row
        row := make(map[string]interface{})

        // Add the column names and values to the map
        for i, column := range columns {
            row[column] = values[i]
        }

        // Add the row map to the data list
        data = append(data, row)
    }

    return data, nil
}

Usage:

// Execute a query and get the rows
rows, err := db.Query("SELECT * FROM mytable")
if err != nil {
    // Handle error
}

// Create a map from the rows
data, err := RowsToMap(rows)
if err != nil {
    // Handle error
}

// Use the data as needed
for _, row := range data {
    fmt.Println(row)
}

This approach allows you to create a map from database rows without specifying the column names or types in advance.

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