Question

我在使用UWP应用程序将数据从csv加载到mysql数据库时遇到问题。我基本上想要做的是：

通过HttpClient读取csv文件中的数据（200k记录，32兆字节）
将数据保存到我的应用程序的临时文件夹
阅读文件并确定需要插入的列
使用MySqlBulkLoader类将csv加载到数据库中

以下是我尝试的代码：

public static async Task<int> MemberEnrollment_GetFromServer_FirstSync(string _url)
{
    int insertedRecords = 0;
    string csv_data = await DownloadDataAsync(_url);

    //StorageFolder localFolder = ApplicationData.Current.RoamingFolder;
    //StorageFile csv = await localFolder.CreateFileAsync(DateTime.Now.ToString("yyyyMMddHHmmssfff") + ".csv", CreationCollisionOption.ReplaceExisting);
    StorageFile csv = await DownloadsFolder.CreateFileAsync(DateTime.Now.ToString("yyyyMMddHHmmssfff") + ".csv");

    var token = Windows.Storage.AccessCache.StorageApplicationPermissions.FutureAccessList.Add(csv);

    try
    {
        await FileIO.WriteTextAsync(csv, csv_data, Windows.Storage.Streams.UnicodeEncoding.Utf8);

        var testRead = await OpenFile(csv.Path, FileAccess.Read);

        //batch insert into the memberenrollment table
        insertedRecords = await DataServices.MemberEnrollment_PostToLocal_Bulk(csv);
    }
    catch (Exception exInsertBatch)
    {
        throw exInsertBatch;
    }
    finally
    {
        if (File.Exists(csv.Path))
            await csv.DeleteAsync(StorageDeleteOption.PermanentDelete);
    }
    return insertedRecords;
}
private static async Task<string> DownloadDataAsync(string url)
    {
        string data = string.Empty;
        using (HttpClient Client = GetHttpClient())
        {
            Client.Timeout = TimeSpan.FromMinutes(60);
            data = await Client.GetStringAsync(url);
        }
        return data;
    }
private async static Task<Stream> OpenFile(string path, FileAccess access)
{
    StorageFile file = await StorageFile.GetFileFromPathAsync(path);
    if (access == FileAccess.Read)
        return await file.OpenStreamForReadAsync();
    else
        return await file.OpenStreamForWriteAsync();
}

public static async Task<int> MemberEnrollment_PostToLocal_Bulk(StorageFile File)
{
    int result = 0;
    List<string> columns = new List<string>();
    List<string> expressions = new List<string>();
    try
    {
        //read the column names
        var lines = await FileIO.ReadLinesAsync(File, Windows.Storage.Streams.UnicodeEncoding.Utf8);
        foreach (var line in lines)
        {
            //columns = string.Join(",", line.Replace("\"", "").Split(new char[] { '\t' }, StringSplitOptions.RemoveEmptyEntries));
            string[] arrHeaders = line.Replace("\"", "").Split(new char[] { '\t' }, StringSplitOptions.RemoveEmptyEntries);
            foreach (string header in arrHeaders)
            {
                columns.Add(header);
            }

            break;
        }
        result = await Task.Run(() =>
        {
            return DataLayer.MemberEnrollment_Write_Bulk(File.Path, columns, expressions);
        });
    }
    catch (Exception ex)
    {
        throw ex;
    }
    return result;
}


public static int MemberEnrollment_Write_Bulk(string FilePath,List<string> columns,List<string> expressions)
{
    int result = 0;
    using (MySqlConnection con = DataProvider.GetConnection())
    {
        MySqlBulkLoader mySqlBulkLoader = new MySqlBulkLoader(con);
        //mySqlBulkLoader.CharacterSet = "utf8";
        mySqlBulkLoader.FieldQuotationCharacter = '"';
        mySqlBulkLoader.Expressions.AddRange(expressions);
        //mySqlBulkLoader.EscapeCharacter = '\\';
        //mySqlBulkLoader.FieldTerminator = "\t";
        mySqlBulkLoader.FileName = FilePath;
        mySqlBulkLoader.LineTerminator = "\\r\\n";
        mySqlBulkLoader.NumberOfLinesToSkip = 1;
        mySqlBulkLoader.TableName = "AC_Memberenrollment";
        mySqlBulkLoader.Timeout = 120;
        mySqlBulkLoader.Columns.AddRange(columns);
        result = mySqlBulkLoader.Load();
    }
    return result;
}

调试器一击到

result = mySqlBulkLoader.Load();

行，它抛出以下错误：

MySql.Data.MySqlClient.MySqlException occurred
  HResult=0x80131500
  Message=Fatal error encountered attempting to read the resultset.
  Source=<Cannot evaluate the exception source>
  StackTrace:
   at MySql.Data.MySqlClient.MySqlCommand.ExecuteReader(CommandBehavior behavior) in C:\Users\ramesh\Downloads\MySql.Data.UWP-master\MySql.Data.UWP-master\MySql.Data.UWP\command.cs:line 545
   at MySql.Data.MySqlClient.MySqlCommand.ExecuteReader() in C:\Users\ramesh\Downloads\MySql.Data.UWP-master\MySql.Data.UWP-master\MySql.Data.UWP\command.cs:line 397
   at MySql.Data.MySqlClient.MySqlCommand.ExecuteNonQuery() in C:\Users\ramesh\Downloads\MySql.Data.UWP-master\MySql.Data.UWP-master\MySql.Data.UWP\command.cs:line 340
   at MySql.Data.MySqlClient.MySqlBulkLoader.Load() in C:\Users\ramesh\Downloads\MySql.Data.UWP-master\MySql.Data.UWP-master\MySql.Data.UWP\BulkLoader.cs:line 277
   at Controller.DAL.DataLayer.MemberEnrollment_Write_Bulk(String FilePath, List`1 columns, List`1 expressions) in E:\Work\Controller\DAL\DataLayer.cs:line 344
   at Controller.Classes.DataServices.<>c__DisplayClass17_0.<MemberEnrollment_PostToLocal_Bulk>b__0() in E:\Work\Controller\Classes\DataServices.cs:line 1333
   at System.Threading.Tasks.Task`1.InnerInvoke()
   at System.Threading.Tasks.Task.Execute()

Inner Exception 1: MySqlException: Fatal error encountered attempting
 to read the resultset.

Inner Exception 2: MySqlException: Error during LOAD DATA LOCAL INFILE

Inner Exception 3: NullReferenceException: Object reference not set to
an instance of an object.

为了理解实际原因，我从https://github.com/nudaca/MySql.Data.UWP下载了MySql.Data.UWP.dll的源代码，发现尝试在FileStream.cs中打开csv文件时发生了实际问题功能

private async void OpenFile(string path, FileAccess access)
{
  StorageFile file = await StorageFile.GetFileFromPathAsync(path);//<--error here
  if (access == FileAccess.Read)
    stream = await file.OpenStreamForReadAsync();
  else
    stream = await file.OpenStreamForWriteAsync();
}

并且实际错误是＆＃34;访问被拒绝＆＃34;！

当我在Workbench中执行从SqlCommand生成的命令字符串时，它会成功加载数据。

我已启用Package.manifest中的功能，用于Internet（客户端），专用网络（客户端和服务器）和可移动存储。

我搜索了各种帖子并尝试了所有解决方案，如下：

我已经花了很长时间在这里张贴这个并撕掉我肥沃的头皮的一部分，同时抓挠我的头来解决这个问题。请帮我批量插入数据！

Answer 1

在您的代码中，您在DownloadsFolder中创建StorageFile csv 文件并使用路径文件获取 OpenFile <中的文件/ strong>方法。 UWP应用程序运行沙箱并且对文件系统的访问权限非常有限，而StorageItems（即StorageFolder和StorageFile）是Windows应用商店应用的规范存储标识符，而不是路径。请参阅Rob的博客Skip the path: stick to the StorageFile。

至于您的问题，您可以尝试使用 LocalFolder 而不是DownloadsFolder，因为存储在我们的本地文件夹（ApplicationData.Current.LocalFolder）中的数据，我们可以使用路径。请参阅File access permissions以详细了解UWP应用可以访问的文件系统位置。

C＃UWP MySql BulkLoader - 无法使用csv

1 个答案: