Question

我有一个类型为MyType的强类型DataTable，我想将其转换为List<MyType>。

我该怎么做？

感谢。

Answer 1

以下是一行：

dataTable.Rows.OfType<DataRow>()
    .Select(dr => dr.Field<MyType>(columnName)).ToList();

[修改：如果不能编译，请在项目中添加对System.Data.DataSetExtensions的引用]

Answer 2

List<MyType> listName = dataTableName.AsEnumerable().Select(m => new MyType()
{
   ID = m.Field<string>("ID"),
   Description = m.Field<string>("Description"),
   Balance = m.Field<double>("Balance"),
}).ToList()

Answer 3

DataTable有Linq扩展方法。

添加对System.Data.DataSetExtensions.dll

的引用

然后包含命名空间：using System.Data.DataSetExtensions

最后，您可以在DataSet和DataTables上使用Linq扩展：

var matches = myDataSet.Tables.First().Where(dr=>dr.Field<int>("id") == 1);

在.Net 2.0上，您仍然可以添加通用方法：

public static List<T> ConvertRowsToList<T>( DataTable input, Convert<DataRow, T> conversion) {
    List<T> retval = new List<T>()
    foreach(DataRow dr in input.Rows)
        retval.Add( conversion(dr) );

    return retval;
}

Answer 4

数据表到列表

    #region "getobject filled object with property reconized"

    public List<T> ConvertTo<T>(DataTable datatable) where T : new()
    {
        List<T> Temp = new List<T>();
        try
        {
            List<string> columnsNames = new List<string>();
            foreach (DataColumn DataColumn in datatable.Columns)
                columnsNames.Add(DataColumn.ColumnName);
            Temp = datatable.AsEnumerable().ToList().ConvertAll<T>(row => getObject<T>(row, columnsNames));
            return Temp;
        }
        catch
        {
            return Temp;
        }

    }
    public T getObject<T>(DataRow row, List<string> columnsName) where T : new()
    {
        T obj = new T();
        try
        {
            string columnname = "";
            string value = "";
            PropertyInfo[] Properties;
            Properties = typeof(T).GetProperties();
            foreach (PropertyInfo objProperty in Properties)
            {
                columnname = columnsName.Find(name => name.ToLower() == objProperty.Name.ToLower());
                if (!string.IsNullOrEmpty(columnname))
                {
                    value = row[columnname].ToString();
                    if (!string.IsNullOrEmpty(value))
                    {
                        if (Nullable.GetUnderlyingType(objProperty.PropertyType) != null)
                        {
                            value = row[columnname].ToString().Replace("$", "").Replace(",", "");
                            objProperty.SetValue(obj, Convert.ChangeType(value, Type.GetType(Nullable.GetUnderlyingType(objProperty.PropertyType).ToString())), null);
                        }
                        else
                        {
                            value = row[columnname].ToString().Replace("%", "");
                            objProperty.SetValue(obj, Convert.ChangeType(value, Type.GetType(objProperty.PropertyType.ToString())), null);
                        }
                    }
                }
            }
            return obj;
        }
        catch
        {
            return obj;
        }
    }

    #endregion

IEnumerable collection To Datatable

    #region "New DataTable"
    public DataTable ToDataTable<T>(IEnumerable<T> collection)
    {
        DataTable newDataTable = new DataTable();
        Type impliedType = typeof(T);
        PropertyInfo[] _propInfo = impliedType.GetProperties();
        foreach (PropertyInfo pi in _propInfo)
            newDataTable.Columns.Add(pi.Name, pi.PropertyType);

        foreach (T item in collection)
        {
            DataRow newDataRow = newDataTable.NewRow();
            newDataRow.BeginEdit();
            foreach (PropertyInfo pi in _propInfo)
                newDataRow[pi.Name] = pi.GetValue(item, null);
            newDataRow.EndEdit();
            newDataTable.Rows.Add(newDataRow);
        }
        return newDataTable;
    }

Answer 5

下面发布并使用反射的ConvertToList方法非常适合我。感谢。

我做了一些修改，使其适用于T属性类型的转换。

public List<T> ConvertToList<T>(DataTable dt)
{
    var columnNames = dt.Columns.Cast<DataColumn>()
            .Select(c => c.ColumnName)
            .ToList();
    var properties = typeof(T).GetProperties();
    return dt.AsEnumerable().Select(row =>
    {
        var objT = Activator.CreateInstance<T>();
        foreach (var pro in properties)
        {
            if (columnNames.Contains(pro.Name))
            {
                 PropertyInfo pI = objT.GetType().GetProperty(pro.Name);
                 pro.SetValue(objT, row[pro.Name] == DBNull.Value ? null : Convert.ChangeType(row[pro.Name], pI.PropertyType));
            }
        }
        return objT;
   }).ToList();
}

希望它有所帮助。问候。

Answer 6

IEnumerable<DataRow> rows = dataTable.AsEnumerable();（System.Data.DataSetExtensions.dll）
IEnumerable<DataRow> rows = dataTable.Rows.OfType<DataRow>();（System.Core.dll）

Answer 7

假设您的DataRow继承自己的类型，比如MyDataRowType，这应该可行：

List<MyDataRowType> list = new List<MyDataRowType>();

foreach(DataRow row in dataTable.Rows)
{
    list.Add((MyDataRowType)row);
}

正如您在评论中所说的那样，假设您使用的是.NET 2.0，并且无法访问LINQ扩展方法。

Answer 8

尝试此代码，这是将数据表转换为列表

的最简单方法

List<DataRow> listtablename = dataTablename.AsEnumerable().ToList();

Answer 9

很不错！

我从@suneelsarraf的答案中进行了一些更新，并删除了Convert.ChangeType()，因为它不断抛出Invalid Cast Exception。看看吧！

#region *** Convert DT to List<Object> ***

    private List<I> ConvertTo<I>(DataTable datatable) where I : class
    {
        List<I> lstRecord = new List<I>();
        try
        {
            List<string> columnsNames = new List<string>();
            foreach (DataColumn DataColumn in datatable.Columns)
                columnsNames.Add(DataColumn.ColumnName);
            lstRecord = datatable.AsEnumerable().ToList().ConvertAll<I>(row => GetObject<I>(row, columnsNames));
            return lstRecord;
        }
        catch
        {
            return lstRecord;
        }

    }

    private I GetObject<I>(DataRow row, List<string> columnsName) where I : class
    {
        I obj = (I)Activator.CreateInstance(typeof(I));
        try
        {
            PropertyInfo[] Properties = typeof(I).GetProperties();
            foreach (PropertyInfo objProperty in Properties)
            {
                string columnname = columnsName.Find(name => name.ToLower() == objProperty.Name.ToLower());
                if (!string.IsNullOrEmpty(columnname))
                {
                    object dbValue = row[columnname];
                    if (dbValue != DBNull.Value)
                    {
                        if (Nullable.GetUnderlyingType(objProperty.PropertyType) != null)
                        {
                            objProperty.SetValue(obj, Convert.ChangeType(dbValue, Type.GetType(Nullable.GetUnderlyingType(objProperty.PropertyType).ToString())), null);
                        }
                        else
                        {
                            objProperty.SetValue(obj, Convert.ChangeType(dbValue, Type.GetType(objProperty.PropertyType.ToString())), null);
                        }
                    }
                }
            }
            return obj;
        }
        catch(Exception ex)
        {
            return obj;
        }
    }

    #endregion

这就是您在代码中使用的方式。

// Other Codes Here
var lstResult = ConvertTo<TEntity>(dataTableName); // Convert DT to List<TEntity>

玩得开心！ 2020年保持安全。

Answer 10

感谢所有帖子...... 我已经使用Linq Query完成了，查看此内容请访问以下链接

http://codenicely.blogspot.com/2012/02/converting-your-datatable-into-list.html

Answer 11

通过<DataRow>调用datatable来扩展名为AsEnumerable的列表。

var mylist = dt.AsEnumerable().ToList();

干杯!!快乐编码

Answer 12

请尝试以下代码：

public List<T> ConvertToList<T>(DataTable dt)
{
    var columnNames = dt.Columns.Cast<DataColumn>()
        .Select(c => c.ColumnName)
        .ToList();
    var properties = typeof(T).GetProperties();
    return dt.AsEnumerable().Select(row =>
    {
        var objT = Activator.CreateInstance<T>();
        foreach (var pro in properties)
        {
            if (columnNames.Contains(pro.Name))
                pro.SetValue(objT, row[pro.Name]);
        }
        return objT;
    }).ToList();
}

Answer 13

您可以将数据表转换为列表。检查以下链接

https://stackoverflow.com/a/35171050/1805776

public static class Helper
{
    public static List<T> DataTableToList<T>(this DataTable dataTable) where T : new()
    {
        var dataList = new List<T>();

        //Define what attributes to be read from the class
        const System.Reflection.BindingFlags flags = System.Reflection.BindingFlags.Public | System.Reflection.BindingFlags.Instance;

        //Read Attribute Names and Types
        var objFieldNames = typeof(T).GetProperties(flags).Cast<System.Reflection.PropertyInfo>().
            Select(item => new
            {
                Name = item.Name,
                Type = Nullable.GetUnderlyingType(item.PropertyType) ?? item.PropertyType
            }).ToList();

        //Read Datatable column names and types
        var dtlFieldNames = dataTable.Columns.Cast<DataColumn>().
            Select(item => new
            {
                Name = item.ColumnName,
                Type = item.DataType
            }).ToList();

        foreach (DataRow dataRow in dataTable.AsEnumerable().ToList())
        {
            var classObj = new T();

            foreach (var dtField in dtlFieldNames)
            {
                System.Reflection.PropertyInfo propertyInfos = classObj.GetType().GetProperty(dtField.Name);

                var field = objFieldNames.Find(x => x.Name == dtField.Name);

                if (field != null)
                {

                    if (propertyInfos.PropertyType == typeof(DateTime))
                    {
                        propertyInfos.SetValue
                        (classObj, convertToDateTime(dataRow[dtField.Name]), null);
                    }
                    else if (propertyInfos.PropertyType == typeof(Nullable<DateTime>))
                    {
                        propertyInfos.SetValue
                        (classObj, convertToDateTime(dataRow[dtField.Name]), null);
                    }
                    else if (propertyInfos.PropertyType == typeof(int))
                    {
                        propertyInfos.SetValue
                        (classObj, ConvertToInt(dataRow[dtField.Name]), null);
                    }
                    else if (propertyInfos.PropertyType == typeof(long))
                    {
                        propertyInfos.SetValue
                        (classObj, ConvertToLong(dataRow[dtField.Name]), null);
                    }
                    else if (propertyInfos.PropertyType == typeof(decimal))
                    {
                        propertyInfos.SetValue
                        (classObj, ConvertToDecimal(dataRow[dtField.Name]), null);
                    }
                    else if (propertyInfos.PropertyType == typeof(String))
                    {
                        if (dataRow[dtField.Name].GetType() == typeof(DateTime))
                        {
                            propertyInfos.SetValue
                            (classObj, ConvertToDateString(dataRow[dtField.Name]), null);
                        }
                        else
                        {
                            propertyInfos.SetValue
                            (classObj, ConvertToString(dataRow[dtField.Name]), null);
                        }
                    }
                    else
                    {

                        propertyInfos.SetValue
                            (classObj, Convert.ChangeType(dataRow[dtField.Name], propertyInfos.PropertyType), null);

                    }
                }
            }
            dataList.Add(classObj);
        }
        return dataList;
    }

    private static string ConvertToDateString(object date)
    {
        if (date == null)
            return string.Empty;

        return date == null ? string.Empty : Convert.ToDateTime(date).ConvertDate();
    }

    private static string ConvertToString(object value)
    {
        return Convert.ToString(ReturnEmptyIfNull(value));
    }

    private static int ConvertToInt(object value)
    {
        return Convert.ToInt32(ReturnZeroIfNull(value));
    }

    private static long ConvertToLong(object value)
    {
        return Convert.ToInt64(ReturnZeroIfNull(value));
    }

    private static decimal ConvertToDecimal(object value)
    {
        return Convert.ToDecimal(ReturnZeroIfNull(value));
    }

    private static DateTime convertToDateTime(object date)
    {
        return Convert.ToDateTime(ReturnDateTimeMinIfNull(date));
    }

    public static string ConvertDate(this DateTime datetTime, bool excludeHoursAndMinutes = false)
    {
        if (datetTime != DateTime.MinValue)
        {
            if (excludeHoursAndMinutes)
                return datetTime.ToString("yyyy-MM-dd");
            return datetTime.ToString("yyyy-MM-dd HH:mm:ss.fff");
        }
        return null;
    }
    public static object ReturnEmptyIfNull(this object value)
    {
        if (value == DBNull.Value)
            return string.Empty;
        if (value == null)
            return string.Empty;
        return value;
    }
    public static object ReturnZeroIfNull(this object value)
    {
        if (value == DBNull.Value)
            return 0;
        if (value == null)
            return 0;
        return value;
    }
    public static object ReturnDateTimeMinIfNull(this object value)
    {
        if (value == DBNull.Value)
            return DateTime.MinValue;
        if (value == null)
            return DateTime.MinValue;
        return value;
    }
}

Answer 14

您可以使用<{3}}

            DataTable dt = GetCustomersDataTable(null);            

            IEnumerable<SelectListItem> lstCustomer = dt.AsEnumerable().Select(x => new SelectListItem()
            {
                Value = x.Field<string>("CustomerId"),
                Text = x.Field<string>("CustomerDescription")
            }).ToList();

            return lstCustomer;

将DataTable转换为List <t> </t>

14 个答案: