我有ASP.Net网站。我有JSON字符串需要导出到物理CSV文件。
private String JsonToCsv(string jsonData, string delimiter)
{
try
{
StringWriter swObj = new StringWriter();
using (var csv = new CsvWriter(swObj))
{
csv.Configuration.SkipEmptyRecords = true;
csv.Configuration.WillThrowOnMissingField = false;
csv.Configuration.Delimiter = delimiter;
using (var dt = jsonStringToTable(jsonData))
{
foreach (DataColumn col in dt.Columns)
{
csv.WriteField(col.ColumnName);
}
csv.NextRecord();
foreach(DataRow row in dt.Rows)
{
for (var i = 0; i < dt.Columns.Count; i++)
{
csv.WriteField(row[i]);
}
csv.NextRecord();
}
}
}
return swObj.ToString();
}
catch (Exception ex)
{
//handle exception
return null;
}
}
private DataTable jsonStringToTable(string jsonContent)
{
DataTable dt = JsonConvert.DeserializeObject<DataTable>(jsonContent);
return dt;
}
public HttpResponseMessage ExportToCSV(string jsonData)
{
string csv = JsonToCsv(jsonData, ",");
HttpResponseMessage res = new HttpResponseMessage(HttpStatusCode.OK);
res.Content = new StringContent(csv);
res.Content.Headers.ContentType = new MediaTypeHeaderValue("text/csv");
res.Content.Headers.ContentDisposition = new ContentDispositionHeaderValue("attachment") { FileName = "export.csv" };
return res;
}
但我既没有得到任何例外，也没有CSV文件获取任何数据。
Export.csv位于根文件夹中。
如何导出JSON＆amp;自动下载文件??
答案 0 :(得分：3)
看来你确实有一个错误，就是你在捕获中压制。
您的第一个错误是您的jsonContent实际上不是json。您的示例中有一个变量赋值jsonContent = [...]。 [...]部分是你真正的json。
要处理这个问题，你只需要更好地编写它，不要将它分配给变量（推荐的方法），或者使用jsonContent.Split(new [] {'='}).Last()来处理实例。 （声明性与命令式方法/策略）。
此外，您正在尝试反序列化为不正确的类型，因为它不反映您的json数据结构。
虽然还有其他方式可以将一个字符串转换为另一个字符串。我同意在这里做正确的事情是反序列化你的对象（或者不事先序列化 - 推荐）。
我正在提供示例控制台应用程序，供您查看处理JsonToCsv操作的两个实现。
dynamic（势在必行）Type并使用System.Reflection。 （以Json.Convert.DeserializeObject<T>()方法声明，后续命令）在此实现中依赖于NewtonSoft.Json程序集（通过NuGet程序包安装它）;它反映了您提供的代码。
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Dynamic;
using System.Reflection;
using Newtonsoft;
namespace JsonToCsvTests
{
using Newtonsoft.Json;
using System.IO;
using System.Threading.Tasks;
class Program
{
static void Main(string[] args)
{
TestJsonToCsv();
Console.ReadLine();
}
static void TestJsonToCsv()
{
string jsonData = @"jsonData = [
{
""DocumentName"": ""Test Document"",
""ActionDate"": ""2015-09-25T16:06:25.083"",
""ActionType"": ""View"",
""ActionPerformedBy"": ""Sreeja SJ""
},
{
""DocumentName"": ""Test Document"",
""ActionDate"": ""2015-09-25T16:12:02.497"",
""ActionType"": ""View"",
""ActionPerformedBy"": ""Sreeja SJ""
},
{
""DocumentName"": ""Test Document"",
""ActionDate"": ""2015-09-25T16:13:48.013"",
""ActionType"": ""View"",
""ActionPerformedBy"": ""Sreeja SJ""
}]";
Console.WriteLine("...using System.Dynamic and casts");
Console.WriteLine();
Console.WriteLine(JsonToCsv(jsonData, ","));
Console.WriteLine();
Console.WriteLine();
Console.WriteLine("...using a provided StrongType with System.Reflection.");
Console.WriteLine();
Console.WriteLine(JsonToCsv<JsonData>(jsonData, ","));
}
static private string JsonToCsv(string jsonContent, string delimiter)
{
var data = jsonStringToTable(jsonContent);
var headers = ((IEnumerable<dynamic>)((IEnumerable<dynamic>)data).First()).Select((prop) => prop.Name).ToArray();
var csvList = new List<string>
{
string.Join(delimiter, headers.Select((prop) => string.Format(@"""{0}""", prop)).ToArray())
};
var lines = ((IEnumerable<dynamic>)data)
.Select(row => row)
.Cast<IEnumerable<dynamic>>()
.Select((instance) => string.Join(delimiter, instance.Select((v) => string.Format(@"""{0}""", v.Value))))
.ToArray();
csvList.AddRange(lines);
return string.Join(Environment.NewLine, csvList );
}
static private string JsonToCsv<T>(string jsonContent, string delimiter) where T : class
{
var data = jsonStringToTable<T>(jsonContent);
var properties = data.First().GetType().GetProperties();
var lines = string.Join(Environment.NewLine,
string.Join(delimiter, properties.Select((propInfo) => string.Format(@"""{0}""", propInfo.Name))),
string.Join(Environment.NewLine, data.Select((row) => string.Join(delimiter, properties.Select((propInfo) => string.Format(@"""{0}""", propInfo.GetValue(row)))))));
return lines;
}
static private dynamic jsonStringToTable(string jsonContent)
{
var json = jsonContent.Split(new[] { '=' }).Last();
return JsonConvert.DeserializeObject<dynamic>(json);
}
static private IEnumerable<T> jsonStringToTable<T>(string jsonContent) where T : class
{
var json = jsonContent.Split(new[] { '=' }).Last();
return JsonConvert.DeserializeObject<IEnumerable<T>>(json);
}
public class JsonData
{
public string DocumentName { get; set; }
public DateTime ActionDate { get; set; }
public string ActionType { get; set; }
public string ActionPerformedBy { get; set; }
}
}
}
...using System.Dynamic and casts
"DocumentName","ActionDate","ActionType","ActionPerformedBy"
"Test Document","9/25/2015 4:06:25 PM","View","Sreeja SJ"
"Test Document","9/25/2015 4:12:02 PM","View","Sreeja SJ"
"Test Document","9/25/2015 4:13:48 PM","View","Sreeja SJ"
...using a provided StrongType with System.Reflection.
"DocumentName","ActionDate","ActionType","ActionPerformedBy"
"Test Document","9/25/2015 4:06:25 PM","View","Sreeja SJ"
"Test Document","9/25/2015 4:12:02 PM","View","Sreeja SJ"
"Test Document","9/25/2015 4:13:48 PM","View","Sreeja SJ"
答案 1 :(得分：0)
这是我用来在我的ASP.NET网站上生成CSV文件
public static class CSVUtils
{
public static void AddCsvLine(bool isFrenchSeparator, StringBuilder csv, params object[] values)
{
foreach (var value in values)
{
csv.Append('"').Append(value).Append('"');
if (isFrenchSeparator)
{
csv.Append(';');
}
else
{
csv.Append(',');
}
}
csv.Append('\r'); // AppendLine() adds a double line break with UTF32Encoding
}
}
public FileContentResult ExportCSV()
{
StringBuilder csv = new StringBuilder();
CSVUtils.AddCsvLine(false, csv, "Field1", "Field2", "Field3");
CSVUtils.AddCsvLine(false, csv, "value1", "value2", "value3");
return this.File(new UTF32Encoding().GetBytes(csv.ToString()), "text/csv", "myfile.csv");
}
我基本上从我的网站调用ExportCSV操作，例如按下按钮，然后下载文件。确保事先从所有昏迷中清除你的JSON，否则会弄乱你的CSV文件。
编辑：特别是对于JSON，你也必须反斜杠每一个“否则会弄乱StringBuilder我猜