因为您假设属性是简单属性,所以我们可以简单地将json的属性视为csv中的字段。

Row 作为 SortedDictionary<string,string>

using Row =SortedDictionary<string,string>; 

我还编写了一个助手类来将json导出到csv。

public class JsonToCsvExporter{

    public JsonToCsvExporter(string json,string sep=","){
        this._json = json;
        this.Sep = sep;
        this.Rows = new List<Row>();
        this.Headers = new List<string>();
        this.Initialize(json);
    }

    private string _json ;

    public IList<Row> Rows{get;set;}
    public IList<string> Headers { get; set; }
    public string Sep {get;set;}=",";

    private void Initialize(string json){
        var o = JArray.Parse(json);
        this.BuildRows(o, null);
        this.Headers = this.Rows.FirstOrDefault().Keys.ToList();
        this.NormailizeRows();
    }
    private void BuildRows(IEnumerable<JToken> tokens, Row row){
        if(row == null){ row = new Row(); }
        foreach( var token in tokens){
            if (token.Type == JTokenType.Property)
            {
                JProperty prop = (JProperty)token;
                if (!prop.Value.HasValues){
                    row.Add(prop.Name,prop.Value.ToString());
                }
            }
            // if it is not a `JProperty`, they shoud have children,
            //     that means it shoud be treated as a brand new line 
            else if (token.HasValues){
                var _row = new Row();
                BuildRows(token.Children(),_row);
            }
        }
        // if current row has fields, add this row
        if (row.Count>0) {
            this.Rows.Add(row);
        }
    }

    // add null for unspecified values
    private void NormailizeRows() {
        foreach (var row in Rows) {
            foreach (var header in Headers) {
                if (!row.ContainsKey(header)) {
                    row.Add(header,null);
                }
            }
        }
    }

    private async Task ForEach<T>(IEnumerable<T> items,Func<T,Task> funcForFirst,Func<T,Task> funcForEach ){
        if(funcForFirst== null ){ throw new ArgumentNullException(nameof(funcForFirst));}
        if(funcForEach== null ){ throw new ArgumentNullException(nameof(funcForEach));}

        var iter = items.GetEnumerator();
        var flag= iter?.MoveNext();
        if(flag==false){ throw new Exception("items MUST have at least one element");}

        await funcForFirst(iter.Current);

        while(iter.MoveNext()!= false){
            await funcForEach(iter.Current);
        }
    }

    public async Task ExportHeader(StreamWriter writer){
        await this.ForEach(this.Headers,
            async header=>{
                await writer.WriteAsync(header);
            },
            async header=>{
                await writer.WriteAsync(this.Sep);
                await writer.WriteAsync(header);
            }
        );
        await writer.WriteLineAsync();
    }

    public async Task ExportBody(StreamWriter writer)
    {
        foreach (var row in this.Rows) {
            await this.ForEach(row,
                async f=>{
                    await writer.WriteAsync(f.Value);
                },
                async f=>{
                    await writer.WriteAsync(this.Sep);
                    await writer.WriteAsync(f.Value);
                }
            );
            await writer.WriteLineAsync();
        }
    }

}

static void Main(string[] args)
{
    var json =@"[{
        'F1': 'hello1',
        'F2': 'world1',
        'F3': 'foo1',
        'F4': 'bar2',
    },{
        'F1': 'Hello2',
        'F4': 'Bar2',
    },{
        'F1': 'Hello3',
        'F2': 'World3',
        'F3': null,
        'F4': 'Bar3',
    }]";
    var fs= new FileStream("xxxx.csv",FileMode.OpenOrCreate);
    using(var writer = new StreamWriter(fs)){
        var exporter= new JsonToCsvExporter(json);
        exporter.ExportHeader(writer).Wait();
        exporter.ExportBody(writer).Wait();
        fs.Flush();
    }
}

我接受了itminus的答案,因为他找到了一个合适的解决方案,并投入了大量的工作。不过,我事先就想好了。以下是我自己的解决方案:

为了解析,我使用了good'ol Newtonsoft.Json,为了序列化为CSV,我使用了jitbit的CsvHelper,如问题中所述。我的解决方案需要一段时间 List<string> 填充了一堆JSON对象,每个对象都有相同的结构,但结构未知。唯一需要说明的是JSON是由键值对填充的,不包含数组或更多“更深层”的对象。

[Authorize]
public class ExportController : Controller
{
    //Dependency-Injection of database context
    private readonly VoteDbContext c;
    public ExportController(VoteDbContext Context)
    {
        c = Context;
    }

    [HttpGet]
    public FileResult Feedback()
    {
        //get all feedback records
        List<string> jsonData = c.UserFeedback.Select(x => x.Data).ToList();
        //example JSON in this list:
        // {"key1":"val1", "key2":"val2", ...}

        CsvExport csvExport = new CsvExport();

        foreach (string json in jsonData)
        {
            //parse json into usable object
            Dictionary<string, string> currentData = JsonConvert.DeserializeObject<Dictionary<string, string>>(json);

            //add new row for each record
            csvExport.AddRow();
            //add values for row
            foreach (KeyValuePair<string, string> kvp in currentData)
                csvExport[kvp.Key] = kvp.Value;
        }

        //return the generated csv file
        return File(csvExport.ExportToBytes(true)/*true -> with header*/, "text/csv", "Feedback.csv");
    } 
}

FileResult 我将返回 File()