@manhng

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CSV to DataTable

March 14, 2020 12:01

CSV to DataTable (edit)

https://github.com/khabt/MVCAjax (đọc thêm về PDF, Ajax, ASP.NET, JavaScript, ...)

Tôi đồng ý rằng trình đọc CSV của Sebastien Lorien là tuyệt vời. Tôi sử dụng nó để xử lý CSV nặng, nhưng tôi cũng đã sử dụng Rissing của Andrew cho các công việc nhỏ và nó phục vụ tốt cho tôi.

Sebastien LorienA reader that provides fast, non-cached, forward-only access to CSV data.

https://www.codeproject.com/Articles/9258/A-Fast-CSV-Reader

AndrewGenericParser is a C# implementation of a parser for delimited and fixed width format files.

https://www.codeproject.com/Articles/11698/A-Portable-and-Efficient-Generic-Parser-for-Flat-F

Những cách sau được lấy từ bài đăng:

https://helpex.vn/question/cach-doc-tep-csv-vao-net-datable-5cbbb3d6ae03f60a1cce52f2

Cách 1: Đơn giản

 private DataTable csvToDataTable(string fileName, char splitCharacter)
{
StreamReader sr = new StreamReader(fileName);
string myStringRow = sr.ReadLine();
var rows = myStringRow.Split(splitCharacter);
DataTable CsvData = new DataTable();
foreach (string column in rows)
{
//creates the columns of new datatable based on first row of csv
CsvData.Columns.Add(column);
}
myStringRow = sr.ReadLine();
while (myStringRow != null)
{
//runs until string reader returns null and adds rows to dt
rows = myStringRow.Split(splitCharacter);
CsvData.Rows.Add(rows);
myStringRow = sr.ReadLine();
}
sr.Close();
sr.Dispose();
return CsvData;
}

Cách 2: Đơn giản và ngắn nhất

 public static DataTable ConvertCSVtoDataTable(string strFilePath)
{
DataTable dt = new DataTable();
using (StreamReader sr = new StreamReader(strFilePath))
{
string[] headers = sr.ReadLine().Split(',');
foreach (string header in headers)
{
dt.Columns.Add(header);
}
while (!sr.EndOfStream)
{
string[] rows = sr.ReadLine().Split(',');
DataRow dr = dt.NewRow();
for (int i = 0; i < headers.Length; i++)
{
dr[i] = rows[i];
}
dt.Rows.Add(dr);
}
}
return dt;
}

Cách 3: Có log lại lỗi trong quá trình xử lý

public class Csv
{
public static DataTable DataSetGet(string filename, string separatorChar, out List<string> errors)
{
errors = new List<string>();
var table = new DataTable("StringLocalization");
using (var sr = new StreamReader(filename, Encoding.Default))
{
string line;
var i = 0;
while (sr.Peek() >= 0)
{
try
{
line = sr.ReadLine();
if (string.IsNullOrEmpty(line)) continue;
var values = line.Split(new[] {separatorChar}, StringSplitOptions.None);
var row = table.NewRow();
for (var colNum = 0; colNum < values.Length; colNum++)
{
var value = values[colNum];
if (i == 0)
{
table.Columns.Add(value, typeof (String));
}
else
{
row[table.Columns[colNum]] = value;
}
}
if (i != 0) table.Rows.Add(row);
}
catch(Exception ex)
{
errors.Add(ex.Message);
}
i++;
}
}
return table;
}
}

Cách 4: Thử xem nhé!

public static DataTable CsvToDataTable(string strFilePath)
{

if (File.Exists(strFilePath))
{

string[] Lines;
string CSVFilePathName = strFilePath;

Lines = File.ReadAllLines(CSVFilePathName);
while (Lines[0].EndsWith(","))
{
Lines[0] = Lines[0].Remove(Lines[0].Length - 1);
}
string[] Fields;
Fields = Lines[0].Split(new char[] { ',' });
int Cols = Fields.GetLength(0);
DataTable dt = new DataTable();
//1st row must be column names; force lower case to ensure matching later on.
for (int i = 0; i < Cols; i++)
dt.Columns.Add(Fields[i], typeof(string));
DataRow Row;
int rowcount = 0;
try
{
string[] ToBeContinued = new string[]{};
bool lineToBeContinued = false;
for (int i = 1; i < Lines.GetLength(0); i++)
{
if (!Lines[i].Equals(""))
{
Fields = Lines[i].Split(new char[] { ',' });
string temp0 = string.Join("", Fields).Replace("\"\"", "");
int quaotCount0 = temp0.Count(c => c == '"');
if (Fields.GetLength(0) < Cols || lineToBeContinued || quaotCount0 % 2 != 0)
{
if (ToBeContinued.GetLength(0) > 0)
{
ToBeContinued[ToBeContinued.Length - 1] += "\n" + Fields[0];
Fields = Fields.Skip(1).ToArray();
}
string[] newArray = new string[ToBeContinued.Length + Fields.Length];
Array.Copy(ToBeContinued, newArray, ToBeContinued.Length);
Array.Copy(Fields, 0, newArray, ToBeContinued.Length, Fields.Length);
ToBeContinued = newArray;
string temp = string.Join("", ToBeContinued).Replace("\"\"", "");
int quaotCount = temp.Count(c => c == '"');
if (ToBeContinued.GetLength(0) >= Cols && quaotCount % 2 == 0 )
{
Fields = ToBeContinued;
ToBeContinued = new string[] { };
lineToBeContinued = false;
}
else
{
lineToBeContinued = true;
continue;
}
}

//modified by Teemo @2016 09 13
//handle ',' and '"'
//Deserialize CSV following Excel's rule:
// 1: If there is commas in a field, quote the field.
// 2: Two consecutive quotes indicate a user's quote.

List<int> singleLeftquota = new List<int>();
List<int> singleRightquota = new List<int>();

//combine fileds if number of commas match
if (Fields.GetLength(0) > Cols)
{
bool lastSingleQuoteIsLeft = true;
for (int j = 0; j < Fields.GetLength(0); j++)
{
bool leftOddquota = false;
bool rightOddquota = false;
if (Fields[j].StartsWith("\""))
{
int numberOfConsecutiveQuotes = 0;
foreach (char c in Fields[j]) //start with how many "
{
if (c == '"')
{
numberOfConsecutiveQuotes++;
}
else
{
break;
}
}
if (numberOfConsecutiveQuotes % 2 == 1)//start with odd number of quotes indicate system quote
{
leftOddquota = true;
}
}

if (Fields[j].EndsWith("\""))
{
int numberOfConsecutiveQuotes = 0;
for (int jj = Fields[j].Length - 1; jj >= 0; jj--)
{
if (Fields[j].Substring(jj,1) == "\"") // end with how many "
{
numberOfConsecutiveQuotes++;
}
else
{
break;
}
}

if (numberOfConsecutiveQuotes % 2 == 1)//end with odd number of quotes indicate system quote
{
rightOddquota = true;
}
}
if (leftOddquota && !rightOddquota)
{
singleLeftquota.Add(j);
lastSingleQuoteIsLeft = true;
}
else if (!leftOddquota && rightOddquota)
{
singleRightquota.Add(j);
lastSingleQuoteIsLeft = false;
}
else if (Fields[j] == "\"") //only one quota in a field
{
if (lastSingleQuoteIsLeft)
{
singleRightquota.Add(j);
}
else
{
singleLeftquota.Add(j);
}
}
}
if (singleLeftquota.Count == singleRightquota.Count)
{
int insideCommas = 0;
for (int indexN = 0; indexN < singleLeftquota.Count; indexN++)
{
insideCommas += singleRightquota[indexN] - singleLeftquota[indexN];
}
if (Fields.GetLength(0) - Cols >= insideCommas) //probabaly matched
{
int validFildsCount = insideCommas + Cols; //(Fields.GetLength(0) - insideCommas) may be exceed the Cols
String[] temp = new String[validFildsCount];
int totalOffSet = 0;
for (int iii = 0; iii < validFildsCount - totalOffSet; iii++)
{
bool combine = false;
int storedIndex = 0;
for (int iInLeft = 0; iInLeft < singleLeftquota.Count; iInLeft++)
{
if (iii + totalOffSet == singleLeftquota[iInLeft])
{
combine = true;
storedIndex = iInLeft;
break;
}
}
if (combine)
{
int offset = singleRightquota[storedIndex] - singleLeftquota[storedIndex];
for (int combineI = 0; combineI <= offset; combineI++)
{
temp[iii] += Fields[iii + totalOffSet + combineI] + ",";
}
temp[iii] = temp[iii].Remove(temp[iii].Length - 1, 1);
totalOffSet += offset;
}
else
{
temp[iii] = Fields[iii + totalOffSet];
}
}
Fields = temp;
}
}
}
Row = dt.NewRow();
for (int f = 0; f < Cols; f++)
{
Fields[f] = Fields[f].Replace("\"\"", "\""); //Two consecutive quotes indicate a user's quote
if (Fields[f].StartsWith("\""))
{
if (Fields[f].EndsWith("\""))
{
Fields[f] = Fields[f].Remove(0, 1);
if (Fields[f].Length > 0)
{
Fields[f] = Fields[f].Remove(Fields[f].Length - 1, 1);
}
}
}
Row[f] = Fields[f];
}
dt.Rows.Add(Row);
rowcount++;
}
}
}
catch (Exception ex)
{
throw new Exception( "row: " + (rowcount+2) + ", " + ex.Message);
}
//OleDbConnection connection = new OleDbConnection(string.Format(@"Provider=Microsoft.Jet.OLEDB.4.0;Data Source={0}; Extended Properties=""text;HDR=Yes;FMT=Delimited"";", FilePath + FileName));
//OleDbCommand command = new OleDbCommand("SELECT * FROM " + FileName, connection);
//OleDbDataAdapter adapter = new OleDbDataAdapter(command);
//DataTable dt = new DataTable();
//adapter.Fill(dt);
//adapter.Dispose();
return dt;
}
else
return null;

//OleDbConnection connection = new OleDbConnection(string.Format(@"Provider=Microsoft.Jet.OLEDB.4.0;Data Source={0}; Extended Properties=""text;HDR=Yes;FMT=Delimited"";", strFilePath));
//OleDbCommand command = new OleDbCommand("SELECT * FROM " + strFileName, connection);
//OleDbDataAdapter adapter = new OleDbDataAdapter(command);
//DataTable dt = new DataTable();
//adapter.Fill(dt);
//return dt;
}

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