C# 输入流，返回到开始

我有一个控制器post方法，需要上传文件：

视图：

没有帮助

在验证方法结束时，将输入流位置设置为0：

HttpContext.Current.Request.Files[0]。InputStream.Position=0

没有帮助

为“reader”对象调用DiscardBufferedData

        reader.DiscardBufferedData();

---

也没有帮助。

我找到了解决办法。我将InputStream复制到另一个流（即MemoryStream），然后我可以为两个流（InputStream和MemoryStream）设置Position=0，并且它可以工作

验证方法：

    public IEnumerable<ValidationResult> Validate(ValidationContext validationContext)
    {
        var results = new List<ValidationResult>();

        if (HttpContext.Current.Request.Files == null || HttpContext.Current.Request.Files.Count == 0 || HttpContext.Current.Request.Files[0].ContentLength == 0)
            results.Add(new ValidationResult("File is not selected or empty", new string[] { "NoFile" }));

        using (MemoryStream ms = new MemoryStream())
        {
            HttpContext.Current.Request.Files[0].InputStream.CopyTo(ms);
            ms.Position = 0;
            using (StreamReader reader = new StreamReader(ms))
            {
                using (var csv = new CsvReader(reader))
                {
                    var enumeraterecords = csv.GetRecords<TemporaryPersonCsv>();

                    if (enumeraterecords != null)
                    {
                        var records = enumeraterecords.ToList();
                        if (records == null || records.Count == 0)
                            results.Add(new ValidationResult("No records in file", new string[] { "NoRecords" }));

                        // find dublicates in CSV file
                        var dublicates = (records.GroupBy(p => p.Fullname.ToLower().Trim()).Where(p => p.Count() > 1).Select(p => p.Key)).ToList();
                        if (dublicates != null && dublicates.Count > 0)
                        {
                            foreach (var dublicateFullname in dublicates)
                            {
                                results.Add(new ValidationResult(String.Concat("There are 2 or more records with fullname='", dublicateFullname, "' in your csv file. Please, fix your file and upload again."), new string[] { "DublicateRecords" }));
                            }
                        }

                        // find dublicates in TemporaryPersons and Persons tables
                        PlugandabandonEntities db = new PlugandabandonEntities();
                        foreach (var record in records)
                        {
                            if (db.TemporaryPerson.Where(p => p.Fullname.ToLower() == record.Fullname.ToLower()).Count() > 0)
                                results.Add(new ValidationResult(String.Concat("Record with fullname='", record.Fullname, "' already exists in TemporaryPersons. Please, fix your file and upload again."), new string[] { "RecordExistsInTemporaryPerson" }));

                            if (db.Person.Where(p => p.Fullname.ToLower() == record.Fullname.ToLower()).Count() > 0)
                                results.Add(new ValidationResult(String.Concat("Record with fullname='", record.Fullname, "' already exists in Persons. Please, fix your file and upload again."), new string[] { "RecordExistsInPersons" }));
                        }

                    }
                    else
                        results.Add(new ValidationResult("No records in file", new string[] { "NoRecords" }));
                }

                reader.DiscardBufferedData();
            }
        }

        HttpContext.Current.Request.Files[0].InputStream.Position = 0;

        return results;
    }

公共IEnumerable验证（ValidationContext ValidationContext） { var results=新列表（）； if（HttpContext.Current.Request.Files==null | | | HttpContext.Current.Request.Files.Count==0 | | | HttpContext.Current.Request.Files[0]。ContentLength==0） 添加（新的ValidationResult（“文件未选中或为空”，新字符串[]{“NoFile”}））； 使用（MemoryStream ms=new MemoryStream（）） { HttpContext.Current.Request.Files[0].InputStream.CopyTo（ms）； ms.Position=0； 使用（StreamReader=新StreamReader（ms）） { 使用（var csv=新的CsvReader（读卡器）） { var enumeraterecords=csv.GetRecords（）； if（枚举记录！=null） { var records=enumeraterecords.ToList（）； if（records==null | | records.Count==0） Add（新的ValidationResult（“文件中没有记录”，新字符串[]{“NoRecords”}））； //在CSV文件中查找副本 var dublicates=（records.GroupBy（p=>p.Fullname.ToLower（）.Trim（））。其中（p=>p.Count（）>1）。选择（p=>p.Key））.ToList（）； if（dublicates！=null&&dublicates.Count>0） { foreach（变量dublicationelname，在dublicates中） { 添加（新的ValidationResult（String.Concat（“您的csv文件中有两个或多个记录的全名为“”，DublicateName为“”），请修复文件并重新上载“”），新字符串[]{“DublicateRecords”}）； } } //在临时人员和人员表中查找dublicates plugandabandoneties db=新的plugandabandoneties（）； foreach（记录中的var记录） { if（db.TemporaryPerson.Where（p=>p.Fullname.ToLower（）==record.Fullname.ToLower（））.Count（）>0） results.Add（新的ValidationResult（String.Concat（“Record with fullname=”，Record.fullname，”）已存在于临时人员中。请修复您的文件并重新上载。”），新字符串[]{“RecordExistsInTemporaryPerson”}）； if（db.Person.Where（p=>p.Fullname.ToLower（）==record.Fullname.ToLower（））.Count（）>0） results.Add（新的ValidationResult（String.Concat（“Record with fullname=”，Record.fullname，“”）已存在于Persons中。请修复您的文件并重新上载。”），新字符串[]{“RecordExistsInPersons”}）； } } 其他的 Add（新的ValidationResult（“文件中没有记录”，新字符串[]{“NoRecords”}））； } reader.discardeBufferedData（）； } } HttpContext.Current.Request.Files[0]。InputStream.Position=0； 返回结果； }

---

然后在控制器方法中有一个“virgin”InputStream，我们可以根据需要使用它；）

您真的想读取文件两次，只是为了验证其内容吗？在模型类的validate方法中有没有其他方法来验证数据？

public class UploadCsvViewModel : IValidatableObject
{
    public IEnumerable<ValidationResult> Validate(ValidationContext validationContext)
    {
        var results = new List<ValidationResult>();

        if (HttpContext.Current.Request.Files == null || HttpContext.Current.Request.Files.Count == 0 || HttpContext.Current.Request.Files[0].ContentLength == 0)
            results.Add(new ValidationResult("File is not selected or empty", new string[] { "NoFile" }));

        using (StreamReader reader = new StreamReader(HttpContext.Current.Request.Files[0].InputStream))
        {
            using (var csv = new CsvReader(reader))
            {
                var enumeraterecords = csv.GetRecords<TemporaryPersonCsv>();

                if (enumeraterecords != null)
                {
                    var records = enumeraterecords.ToList();
                    if (records == null || records.Count == 0)
                        results.Add(new ValidationResult("No records in file", new string[] { "NoRecords" }));

                    // different validation, according with business logic

                }
                else
                    results.Add(new ValidationResult("No records in file", new string[] { "NoRecords" }));
            }
        }
        return results;
    }
}

var records = csv.GetRecords<TemporaryPersonCsv>().ToList();

using (MemoryStream ms = new MemoryStream())
{
    HttpContext.Current.Request.Files[0].InputStream.CopyTo(ms, HttpContext.Current.Request.Files[0].ContentLength);

        reader.DiscardBufferedData();

    public IEnumerable<ValidationResult> Validate(ValidationContext validationContext)
    {
        var results = new List<ValidationResult>();

        if (HttpContext.Current.Request.Files == null || HttpContext.Current.Request.Files.Count == 0 || HttpContext.Current.Request.Files[0].ContentLength == 0)
            results.Add(new ValidationResult("File is not selected or empty", new string[] { "NoFile" }));

        using (MemoryStream ms = new MemoryStream())
        {
            HttpContext.Current.Request.Files[0].InputStream.CopyTo(ms);
            ms.Position = 0;
            using (StreamReader reader = new StreamReader(ms))
            {
                using (var csv = new CsvReader(reader))
                {
                    var enumeraterecords = csv.GetRecords<TemporaryPersonCsv>();

                    if (enumeraterecords != null)
                    {
                        var records = enumeraterecords.ToList();
                        if (records == null || records.Count == 0)
                            results.Add(new ValidationResult("No records in file", new string[] { "NoRecords" }));

                        // find dublicates in CSV file
                        var dublicates = (records.GroupBy(p => p.Fullname.ToLower().Trim()).Where(p => p.Count() > 1).Select(p => p.Key)).ToList();
                        if (dublicates != null && dublicates.Count > 0)
                        {
                            foreach (var dublicateFullname in dublicates)
                            {
                                results.Add(new ValidationResult(String.Concat("There are 2 or more records with fullname='", dublicateFullname, "' in your csv file. Please, fix your file and upload again."), new string[] { "DublicateRecords" }));
                            }
                        }

                        // find dublicates in TemporaryPersons and Persons tables
                        PlugandabandonEntities db = new PlugandabandonEntities();
                        foreach (var record in records)
                        {
                            if (db.TemporaryPerson.Where(p => p.Fullname.ToLower() == record.Fullname.ToLower()).Count() > 0)
                                results.Add(new ValidationResult(String.Concat("Record with fullname='", record.Fullname, "' already exists in TemporaryPersons. Please, fix your file and upload again."), new string[] { "RecordExistsInTemporaryPerson" }));

                            if (db.Person.Where(p => p.Fullname.ToLower() == record.Fullname.ToLower()).Count() > 0)
                                results.Add(new ValidationResult(String.Concat("Record with fullname='", record.Fullname, "' already exists in Persons. Please, fix your file and upload again."), new string[] { "RecordExistsInPersons" }));
                        }

                    }
                    else
                        results.Add(new ValidationResult("No records in file", new string[] { "NoRecords" }));
                }

                reader.DiscardBufferedData();
            }
        }

        HttpContext.Current.Request.Files[0].InputStream.Position = 0;

        return results;
    }