[C#] 將 Dictionary 轉為 JSON

之前筆記 [C#] 將 JSON 轉為 Dictionary 紀錄到如果將 JSON file 轉為 C# 的 Dictionary 來做後續加工處理，當然有 JSON to Dictionary 就需要有 Dictionary to JSON 囉

基本環境說明

macOS Catalina 10.15.2
.NET Core SDK 3.1.101
C# 8.0

程式碼與實際效果

程式碼

public static JObject ToJson(Dictionary<string, string> keyValues)
{
    JContainer result = null;
    var setting = new JsonMergeSettings {MergeArrayHandling = MergeArrayHandling.Merge};
    foreach (var pathValue in keyValues)
    {
        if (result == null)
        {
            result = UnflattenSingle(pathValue);
        }
        else
        {
            result.Merge(UnflattenSingle(pathValue), setting);
        }
    }
    return result as JObject;
}

private static JContainer UnflattenSingle(KeyValuePair<string, string> keyValue)
{
    var path = keyValue.Key;
    var value = keyValue.Value;
    var pathSegments = SplitPath(path);

    JContainer lastItem = null;
    //build from leaf to root
    foreach (var pathSegment in pathSegments.Reverse())
    {
        var type = GetJsonType(pathSegment);
        switch (type)
        {
            case JsonType.Object:
                var obj = new JObject();
                if (null == lastItem)
                {
                    obj.Add(pathSegment,value);
                }
                else
                {
                    obj.Add(pathSegment,lastItem);
                }
                lastItem = obj;
                break;
            case JsonType.Array:
                var array = new JArray();
                var index = GetArrayIndex(pathSegment);
                array = FillEmpty(array, index);
                if (lastItem == null)
                {
                    array[index] = value;
                }
                else
                {
                    array[index] = lastItem;
                }
                lastItem = array;
                break;
        }
    }
    return lastItem;
}

public static IList<string> SplitPath(string path){
    IList<string> result = new List<string>();
    var reg = new Regex(@"(?!\.)([^. ^\[\]]+)|(?!\[)(\d+)(?=\])");
    foreach (Match match in reg.Matches(path))
    {
        result.Add(match.Value);
    }
    return result;
}

private static JArray FillEmpty(JArray array, int index)
{
    for (var i = 0; i <= index; i++)
    {
        array.Add(null);
    }
    return array;
}

private enum JsonType{
    Object, Array
}
private static JsonType GetJsonType(string pathSegment)
{
    return int.TryParse(pathSegment, out var _) ? JsonType.Array : JsonType.Object;
}

private static int GetArrayIndex(string pathSegment)
{
    if (int.TryParse(pathSegment, out var result))
    {
        return result;
    }
    throw new Exception("Unable to parse array index: " + pathSegment);
}

使用方式
```
ToJson(jsonDictionary)).ToString();
```
實際效果
- 原始 Dictionary
- json string

心得

程式碼數量看來把 dictionary 轉回 json 比起把 json 攤平成 dictionary 容易許多，另外的問題是資料型態有可能跑掉：int、bool 都變成了 string，這點要特別留意，除此之外初步滿足功能需求

文章目錄

[C#] 將 Dictionary 轉為 JSON

基本環境說明

程式碼與實際效果

心得

參考資訊